



Network Working Group                                  J. Preuß Mattsson
Internet-Draft                                               G. Selander
Updates: 6698 (if approved)                                  Ericsson AB
Intended status: Standards Track                                 S. Raza
Expires: 3 September 2026                          University of Glasgow
                                                              J. Höglund
                                                                 RISE AB
                                                              M. Furuhed
                                                               IN Groupe
                                                            2 March 2026


          CBOR Encoded X.509 Certificates (C509 Certificates)
                  draft-ietf-cose-cbor-encoded-cert-17

Abstract

   This document specifies a CBOR encoding of X.509 certificates.  The
   resulting certificates are called C509 certificates.  The CBOR
   encoding supports a large subset of RFC 5280, common certificate
   profiles and is extensible.

   Two types of C509 certificates are defined.  One type is an
   invertible CBOR re-encoding of DER-encoded X.509 certificates with
   the signature field copied from the DER encoding.  The other type is
   identical except that the signature is over the CBOR encoding instead
   of the DER encoding, avoiding the use of ASN.1.  Both types of
   certificates have the same semantics as X.509 and the same reduced
   size compared to X.509.

   The document also specifies CBOR encoded data structures for
   certificate (signing) requests and certificate request templates, new
   COSE headers, as well as a TLS certificate type and a file format for
   C509.  This document updates RFC 6698; the TLSA selectors registry is
   extended to include C509 certificates.

About This Document

   This note is to be removed before publishing as an RFC.

   Status information for this document may be found at
   https://datatracker.ietf.org/doc/draft-ietf-cose-cbor-encoded-cert/.

   Discussion of this document takes place on the CBOR Object Signing
   and Encryption Working Group mailing list (mailto:cose@ietf.org),
   which is archived at https://mailarchive.ietf.org/arch/browse/cose/.
   Subscribe at https://www.ietf.org/mailman/listinfo/cose/.




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   Source for this draft and an issue tracker can be found at
   https://github.com/cose-wg/CBOR-certificates.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 3 September 2026.

Copyright Notice

   Copyright (c) 2026 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   5
   3.  C509 Certificate  . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Message Fields  . . . . . . . . . . . . . . . . . . . . .   6
     3.2.  Encoding of subjectPublicKey and issuerSignatureValue . .  11
     3.3.  Encoding of Extensions  . . . . . . . . . . . . . . . . .  12
     3.4.  COSE Header Parameters  . . . . . . . . . . . . . . . . .  18
     3.5.  Private Key Structures  . . . . . . . . . . . . . . . . .  19
     3.6.  Deterministic Encoding  . . . . . . . . . . . . . . . . .  20
     3.7.  C509 Name in TLS and DTLS . . . . . . . . . . . . . . . .  21
   4.  C509 Certificate (Signing) Request  . . . . . . . . . . . . .  21
     4.1.  Certificate Request Types . . . . . . . . . . . . . . . .  22



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     4.2.  Subject Signature Algorithm . . . . . . . . . . . . . . .  23
     4.3.  Certificate Request Attributes  . . . . . . . . . . . . .  23
     4.4.  Certificate Request Template  . . . . . . . . . . . . . .  24
   5.  C509 Processing and Certificate Issuance  . . . . . . . . . .  26
   6.  Legacy Considerations . . . . . . . . . . . . . . . . . . . .  27
   7.  Expected Certificate Sizes  . . . . . . . . . . . . . . . . .  27
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  29
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  29
     9.1.  C509 Certificate Types Registry . . . . . . . . . . . . .  30
     9.2.  C509 Certificate Request Types Registry . . . . . . . . .  31
     9.3.  C509 Private Key Types Registry . . . . . . . . . . . . .  31
     9.4.  C509 Certificate Request Templates Types Registry . . . .  32
     9.5.  C509 RDN Attributes Registry  . . . . . . . . . . . . . .  32
     9.6.  C509 CR Attributes Registry . . . . . . . . . . . . . . .  36
     9.7.  C509 Extensions Registry  . . . . . . . . . . . . . . . .  37
     9.8.  C509 Certificate Policies Registry  . . . . . . . . . . .  41
     9.9.  C509 Policies Qualifiers Registry . . . . . . . . . . . .  44
     9.10. C509 Information Access Registry  . . . . . . . . . . . .  44
     9.11. C509 Extended Key Usages Registry . . . . . . . . . . . .  46
     9.12. C509 General Names Registry . . . . . . . . . . . . . . .  48
     9.13. C509 Signature Algorithms Registry  . . . . . . . . . . .  50
     9.14. C509 Public Key Algorithms Registry . . . . . . . . . . .  54
     9.15. COSE Header Parameters Registry . . . . . . . . . . . . .  57
     9.16. Media Type Application Registry . . . . . . . . . . . . .  57
     9.17. CoAP Content-Formats Registry . . . . . . . . . . . . . .  63
     9.18. TLS Certificate Types Registry  . . . . . . . . . . . . .  65
     9.19. TLSA Selectors Registry . . . . . . . . . . . . . . . . .  65
     9.20. EDHOC Authentication Credential Types Registry  . . . . .  66
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  66
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  66
     10.2.  Informative References . . . . . . . . . . . . . . . . .  69
   Appendix A.  C509 Certificate Examples  . . . . . . . . . . . . .  72
     A.1.  Example: RFC 7925 profiled X.509 Certificate  . . . . . .  73
     A.2.  Example: IEEE 802.1AR profiled X.509 Certificate  . . . .  78
     A.3.  Example: CAB Baseline ECDSA HTTPS X.509 Certificate . . .  82
     A.4.  Example: CAB Baseline RSA HTTPS X.509 Certificate . . . .  84
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  87
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  88
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  88

1.  Introduction

   One of the challenges with deploying a Public Key Infrastructure
   (PKI) for the Internet of Things (IoT) is the size and parsing of
   X.509 public key certificates [RFC5280], since those are not
   optimized for constrained environments [RFC7228].  Large certificate
   chains are also problematic in non-constrained protocols such as EAP-
   TLS [RFC9190] [RFC9191] where authenticators typically drop an EAP



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   session after only 40–50 round-trips, QUIC [RFC9000] where the
   latency increases significantly unless the server sends less than
   three times as many bytes as received prior to validating the client
   address, and RPKI [RFC6487] where a single certificate can be very
   large.  More compact certificate representations are therefore
   desirable in many use cases.

   X.509 certificates are defined with Abstract Syntax Notation One
   (ASN.1) and encoded using the Distinguished Encoding Rules (DER).
   This document specifies an alternative encoding of X.509
   certificates, using the Concise Binary Object Representation (CBOR)
   [RFC8949], initially proposed in [X.509-IoT].  The use of a more
   compact encoding reduces the certificate size, which has known
   performance benefits in terms of decreased communication overhead,
   power consumption, latency, storage, etc.  The re-encoding of X.509
   is called C509 and the resulting certificates are termed C509
   certificates.  C509 is not a general CBOR encoding for ASN.1 data
   structures.

   CBOR is a data format designed for small code size and small message
   size to support systems with very limited memory, processor power,
   and instruction sets.  CBOR builds on the JSON data model but extends
   it by, e.g., encoding binary data directly without base64 conversion.
   In addition to the binary CBOR encoding, CBOR also has a diagnostic
   notation that is readable and editable by humans, simplifying
   development and debugging.  The Concise Data Definition Language
   (CDDL) [RFC8610] provides a way to express structures for protocol
   messages and APIs that use CBOR.  RFC 8610 also extends the
   diagnostic notation.  For a complete specification and examples, see
   [RFC8949], [RFC8610], and [RFC8742].  Implementors can get familiar
   with CBOR by using the CBOR playground [CborMe].

   The C509 encoding supports a large subset of RFC 5280 and all
   certificates compatible with the RFC 7925, IEEE 802.1AR (DevID), CAB
   Baseline [CAB-TLS], [CAB-Code], RPKI [RFC6487], eUICC [GSMA-eUICC]
   profiled X.509 certificates, and is designed to render a compact
   encoding of certificates used in constrained environments.  This
   document does not specify a certificate profile.

   CAB Baseline Requirements [CAB-TLS], RFC 7925 [RFC7925], IEEE 802.1AR
   [IEEE-802.1AR], and CNSA 1.0 [RFC8603] specify certificate profiles
   which can be applied to certificate based authentication with, e.g.,
   TLS [RFC8446], QUIC [RFC9000], DTLS [RFC9147], COSE [RFC9052], EDHOC
   [RFC9528], or Compact TLS 1.3 [I-D.ietf-tls-ctls].  RFC 7925
   [RFC7925], RFC7925bis [I-D.ietf-uta-tls13-iot-profile], and IEEE
   802.1AR [IEEE-802.1AR] specifically target Internet of Things
   deployments.




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   C509 is deployed in, e.g., in-vehicle and vehicle-to-cloud
   communication, Unmanned Aircraft Systems (UAS), and Global Navigation
   Satellite System (GNSS).  When used to re-encode DER-encoded X.509
   certificates, the CBOR encoding can in many cases reduce the size of
   RFC 7925 profiled certificates by over 50%.

   C509 is designed to be extensible to additional features of X.509,
   for example support for new algorithms, including new post-quantum
   algorithms, which can be registered in the IANA registry as they
   become specified, see Section 9.13.

   Two types of C509 are defined using the same CBOR encoding and
   differing only in what is being signed:

   1.  An invertible CBOR re-encoding of DER-encoded X.509 certificates
       [RFC5280], which can be reversed to obtain the original DER-
       encoded X.509 certificate.  Due to the widespread deployment of
       X.509 it is necessary to allow backward compatibility.

   2.  Natively signed C509 certificates, where the signature is
       calculated over the CBOR encoding instead of over the DER
       encoding.  This removes the need for ASN.1 and DER parsing and
       the associated complexity but they are not backwards compatible
       with implementations requiring DER-encoded X.509.

   Natively signed C509 certificates can be applied in devices that are
   only required to authenticate to natively signed C509 certificate
   compatible servers, which is not a major restriction for many IoT
   deployments where the parties issuing and verifying certificates can
   be a restricted ecosystem.

   This document also specifies C509 Certificate Requests, see
   Section 4; COSE headers for use of the C509 certificates with COSE,
   see Section 9.15; a TLS certificate type for use of the C509
   certificates with TLS and QUIC (with or without additional TLS
   certificate compression), see Section 9.18; and a C509 file format.
   The TLSA selectors registry is extended to include C509 certificates,
   thus this document updates [RFC6698].

2.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.





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   This specification makes use of the terminology in [RFC2986],
   [RFC5280], [RFC7228], [RFC8610], and [RFC8949].  When referring to
   CBOR, this specification always refers to Deterministically Encoded
   CBOR as specified in Sections 4.2.1 and 4.2.2 of [RFC8949].

3.  C509 Certificate

   This section specifies the content and encoding for C509
   certificates, with the overall objective to produce a very compact
   representation supporting large parts of [RFC5280], and everything in
   [RFC7925], [IEEE-802.1AR], RPKI [RFC6487], GSMA eUICC [GSMA-eUICC],
   and CAB Baseline [CAB-TLS] [CAB-Code].  In the CBOR encoding, static
   fields are elided, elliptic curve points and time values are
   compressed, OID are replaced with short integers or complemented with
   CBOR OID encoding [RFC9090], and redundant encoding is removed.
   Combining these different components reduces the certificate size
   significantly, which is not possible with general purpose compression
   algorithms, see Figure 5.

   The C509 certificate can be either a CBOR re-encoding of a DER-
   encoded X.509 certificate, in which case the signature is calculated
   on the DER-encoded ASN.1 data in the X.509 certificate, or a natively
   signed C509 certificate, in which case the signature is calculated
   directly on the CBOR encoded data.  In both cases the certificate
   content is adhering to the restrictions given by [RFC5280].  The re-
   encoding is known to work with DER-encoded certificates but might
   work with other canonical encodings.  The re-encoding does not work
   for BER encoded certificates.

   In the encoding described below, the elements in arrays are always
   encoded in the same order as elements of the corresponding SEQUENCE
   or SET in the DER encoding.

3.1.  Message Fields

   The X.509 fields and their CBOR encodings are described in this
   section, and used in the definition of C509 certificates, see
   Figure 1.

   The following Concise Data Definition Language (CDDL) defines the
   CBOR array C509Certificate and the CBOR sequence [RFC8742]
   TBSCertificate.  The member names therefore only have documentary
   value.  Applications not requiring a CBOR item MAY represent C509
   certificates with the CBOR sequence ~C509Certificate (unwrapped
   C509Certificate).  Examples are given in the appendices, e.g.,
   Appendix A.1.





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   C509Certificate = [
      TBSCertificate,
      issuerSignatureValue : any,
   ]

   ; The elements of the following group are used in a CBOR Sequence:
   TBSCertificate = (
      c509CertificateType: int,
      certificateSerialNumber: CertificateSerialNumber,
      issuerSignatureAlgorithm: AlgorithmIdentifier,
      issuer: Name / null,
      validityNotBefore: ~time,
      validityNotAfter: ~time / null,
      subject: Name,
      subjectPublicKeyAlgorithm: AlgorithmIdentifier,
      subjectPublicKey: Defined,
      extensions: Extensions,
   )

   CertificateSerialNumber = ~biguint

   Name = [ * RDNAttribute ] / SpecialText

   RDNAttribute = (( attributeType: int, attributeValue: SpecialText ) //
                   ( attributeType: ~oid, attributeValue: bytes ))

   AlgorithmIdentifier = int / ~oid /
                       [ algorithm: ~oid, parameters: bytes ]

   Extensions = [ * Extension ] / int

   Extension = (( extensionID: int, extensionValue: Defined ) //
                ( extensionID: ~oid, extensionValue: bytes / [ bytes ] ))

   SpecialText = text / bytes / tag

   Defined = any .ne undefined

   tag = #6

                    Figure 1: CDDL for C509Certificate.

   C509 certificates are defined in terms of DER-encoded X.509
   certificates [RFC5280] as detailed in the following subsections.







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3.1.1.  version

   The 'version' field is encoded in the 'c509CertificateType' CBOR int.
   The field 'c509CertificateType' also indicates the type of the C509
   certificate.  Two types are defined in this document: natively signed
   C509 certificates, following X.509 v3 (c509CertificateType = 2); and
   CBOR re-encoded X.509 v3 DER certificate (c509CertificateType = 3),
   see Section 9.1.  The number of elements in TBSCertificate is fixed
   and determined by the type.  Additional types may be added in the
   future.

3.1.2.  serialNumber

   The 'serialNumber' INTEGER value field is encoded as the unwrapped
   CBOR unsigned bignum (~biguint) 'certificateSerialNumber'.  Any
   leading 0x00 byte (to indicate that the number is not negative) is
   therefore omitted.

3.1.3.  signature

   The 'signature' field, containing the signature algorithm including
   parameters, is encoded as a CBOR int (see Section 9.13) or as an
   array with an unwrapped CBOR OID tag [RFC9090] optionally followed by
   the parameters encoded as a CBOR byte string.

3.1.4.  issuer

   In the general case, the sequence of 'RDNAttribute' is encoded as a
   CBOR array consisting of RDNAttribute elements.
   RelativeDistinguishedName with more than one AttributeTypeAndValue is
   not supported.  Each RDNAttribute is CBOR encoded as (type, value)
   either as a (int, SpecialText) pair, or a (~oid, bytes) tuple.

   In the former case, the absolute value of the int encodes the
   attribute type (see Figure 11) and the sign is used to represent the
   character string type in the X.509 certificate; positive for
   utf8String, negative for printableString.  Attribute values which are
   always of type IA5String are unambiguously represented using a non-
   negative int.  Examples include emailAddress and domainComponent (see
   [RFC5280]).  In CBOR, all text strings are UTF-8 encoded and in
   natively signed C509 certificates all CBOR ints SHALL be non-
   negative.  Text strings SHALL still adhere to any [RFC5280]
   restrictions. serialNumber SHALL only contain the 74-character subset
   of ASCII allowed by printableString and countryName SHALL have length
   2.  CBOR encoding is allowed for IA5String (if this is the only
   allowed type, e.g., emailAddress), printableString and utf8String,
   whereas the string types teletexString, universalString, and
   bmpString are not supported.



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   The text strings are further optimized as follows:

   *  If the text string has an even length ≥ 2 and contains only the
      symbols '0'–'9' or 'a'–'f', it is encoded as a CBOR byte string.

   *  If the text string contains an EUI-64 of the form "HH-HH-HH-HH-HH-
      HH-HH-HH" where each 'H' is one of the symbols '0'-'9' or 'A'-'F',
      it is encoded as a CBOR tagged MAC address using the CBOR tag 48,
      see Section 2.4 of [RFC9542].  If of the form "HH-HH-HH-FF-FE-HH-
      HH-HH", it is encoded as a 48-bit MAC address, otherwise as a
      64-bit MAC address.  See example in Appendix A.1.

   *  Otherwise it is encoded as a CBOR text string.

   The final encoding of the extension value may therefore be text,
   bytes, or tag, i.e., SpecialText.  If Name contains a single 'common
   name' attribute with attributeType = +1, it is for compactness
   encoded as just the SpecialText containing the single attribute
   value.

   In natively signed C509 certificates, bytes and tag 48 do not
   correspond to any predefined text string encoding and may also be
   used for other attribute types.

   If the 'issuer' field is identical to the 'subject' field, e.g., in
   case of self-signed certificates, then the 'issuer' field MUST be
   encoded as the CBOR simple value null (0xf6).

3.1.5.  validity

   The 'notBefore' and 'notAfter' fields are encoded as unwrapped CBOR
   epoch-based date/time (~time) where the tag content is an unsigned
   integer.  In POSIX time, leap seconds are ignored, with a leap second
   having the same POSIX time as the second before it.  Compression of
   X.509 certificates with the time 23:59:60 UTC is therefore not
   supported.  Note that RFC 5280 mandates encoding of dates through the
   year 2049 as UTCTime, and later dates as GeneralizedTime.  The value
   "99991231235959Z" (no expiration date) is encoded as the CBOR simple
   value null.

3.1.6.  subject

   The 'subject' field is encoded exactly like issuer, except that the
   CBOR simple value is not a valid value.







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3.1.7.  subjectPublicKeyInfo

   The 'AlgorithmIdentifier' field including parameters is encoded as
   the CBOR int 'subjectPublicKeyAlgorithm' (see Section 9.14) or as an
   array with an unwrapped CBOR OID tag [RFC9090] optionally followed by
   the parameters encoded as a CBOR byte string.

   In general, the 'subjectPublicKey' BIT STRING value field is encoded
   as a CBOR byte string, but may be encoded as a CBOR item of any type
   except undefined (see Section 4.4).  This specification assumes the
   BIT STRING has zero unused bits, and the unused bits byte is omitted.
   For rsaEncryption and id-ecPublicKey, the encoding of
   subjectPublicKey is further optimized as described in Section 3.2.

3.1.8.  issuerUniqueID

   Not supported.

3.1.9.  subjectUniqueID

   Not supported.

3.1.10.  extensions

   The 'extensions' field is encoded either as a CBOR array or as a CBOR
   int.  An omitted 'extensions' field is encoded as an empty CBOR
   array.

   Each 'extensionID' in the CBOR array is encoded either as a CBOR int
   (see Section 9.7) or as an unwrapped CBOR OID tag [RFC9090].

   *  If 'extensionID' is encoded as a CBOR int, it is followed by a
      CBOR item of any type except undefined (see Section 4.4), and the
      sign of the int is used to encode if the extension is critical:
      Critical extensions are encoded with a negative sign and non-
      critical extensions are encoded with a positive sign.  If the CBOR
      array contains exactly two ints and the absolute value of the
      first int is 2 (corresponding to keyUsage, see Section 3.3), the
      CBOR array is omitted and the extensions is encoded as a single
      CBOR int with the absolute value of the second int and the sign of
      the first int.

   *  If extensionID is encoded as an unwrapped CBOR OID tag, it is
      followed by the DER-encoded extnValue encoded in the following
      way:

      -  if the extension is non-critical, the extnValue OCTET STRING
         value field is encoded as a CBOR byte string;



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      -  if the extension is critical, the extnValue OCTET STRING value
         field is encoded as a CBOR byte string and further wrapped in a
         CBOR array consisting of only this element.

   The processing of critical and non-critical extensions is specified
   in Section 4.2 of [RFC5280].

   The currently defined extension values for which there is CBOR int
   encoded 'extensionID' are specified in Section 3.3.  The extensions
   mandated to be supported by [RFC7925] and [IEEE-802.1AR] are given
   special treatment.

   More details about extensions in Section 3.3.

3.1.11.  signatureAlgorithm

   The 'signatureAlgorithm' field is always the same as the 'signature'
   field and therefore omitted from the CBOR encoding.

3.1.12.  signatureValue

   In general, the 'signatureValue' BIT STRING value field is encoded as
   the CBOR byte string issuerSignatureValue.  This specification
   assumes that the BIT STRING has zero unused bits, and the unused bits
   byte is omitted.  For natively signed C509 certificates, the
   signatureValue is calculated over the CBOR sequence TBSCertificate.
   For ECDSA, the encoding of issuerSignatureValue is further optimized
   as described in Section 3.2

3.2.  Encoding of subjectPublicKey and issuerSignatureValue

3.2.1.  Encoding of subjectPublicKey

   For RSA public keys (rsaEncryption), the SEQUENCE and INTEGER type
   and length fields are omitted, and the two INTEGER value fields
   (modulus, exponent) are encoded as an array of two unwrapped CBOR
   unsigned bignum (~biguint), i.e., [ modulus : ~biguint, exponent :
   ~biguint ].  If the exponent is 65537, the array and the exponent are
   omitted and subjectPublicKey consists of only the modulus encoded as
   an unwrapped CBOR unsigned bignum (~biguint).











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   For elliptic curve public keys in Weierstrass form (id-ecPublicKey),
   keys may be point compressed as defined in Section 2.3.3 of [SECG].
   Native C509 certificates with Weierstrass form keys use the octets
   0x02, 0x03, and 0x04 as defined in [SECG].  If a DER-encoded
   certificate with an uncompressed public key of type id-ecPublicKey is
   CBOR encoded with point compression, then the octet 0xfe is used
   instead of 0x02 to represent an even y-coordinate, and the octet 0xfd
   is used instead of 0x03 to represent an odd y-coordinate.

3.2.2.  Encoding of issuerSignatureValue

   For ECDSA signatures, the SEQUENCE and INTEGER type and length fields
   as well as any leading 0x00 byte (to indicate that the number is not
   negative) are omitted.  Each of the two INTEGER value fields are then
   padded with leading zeroes to the same fixed length, given by the
   number of bytes needed to represent the order n of the cyclic
   subgroup used with the algorithm.  For example, for P-256, the number
   of bytes for each integer is 32.  The resulting byte string is
   encoded as a CBOR byte string.

3.3.  Encoding of Extensions

   The 'extensions' field is encoded as specified in Section 3.1.10 with
   further details provided in this section.

   For some extensions, the CBOR int encoded extensionID is only
   supported for commonly used values of the extension.  In case of
   extension values for which the CBOR int encoded extensionID is not
   supported, the extension MUST be encoded using the unwrapped CBOR OID
   tag encoded extensionID.

   A note on extensionID naming: in existing OID databases, most IDs can
   be found in versions with and without an 'id-pe' or 'id-ce' prefix.
   We have excluded the prefix for the commonly used extensions defined
   in [RFC5280] and included them for extensions defined elsewhere.

   CBOR encoding of the following extension values is fully supported:

   *  Subject Key Identifier (subjectKeyIdentifier).  In natively signed
      certificates, KeyIdentifier SHOULD be composed of the leftmost
      160-bits of the SHA-256 hash of the CBOR encoded subjectPublicKey.
      Other methods of generating unique numbers can be used.  The
      extensionValue is encoded as follows:

      KeyIdentifier = bytes
      SubjectKeyIdentifier = KeyIdentifier





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   *  Key Usage (keyUsage).  The 'KeyUsage' BIT STRING is interpreted as
      an unsigned integer in network byte order and encoded as a CBOR
      int.  See Section 3.1.10 for special encoding in case keyUsage is
      the only extension present.

      KeyUsage = uint

   *  Policy Mappings (policyMappings). extensionValue is encoded as
      follows:

      PolicyMappings = [
        + (issuerDomainPolicy: int/~oid, subjectDomainPolicy: int/~oid)
      ]

   *  Basic Constraints (basicConstraints).  If 'cA' = false then
      extensionValue = -2, if 'cA' = true and 'pathLenConstraint' is not
      present then extensionValue = -1, and if 'cA' = true and
      'pathLenConstraint' is present then extensionValue =
      pathLenConstraint.

      BasicConstraints = int

   *  Policy Constraints (policyConstraints). extensionValue is encoded
      as follows:

      PolicyConstraints = [
        requireExplicitPolicy: uint / null,
        inhibitPolicyMapping: uint / null,
      ]

   *  Extended Key Usage (extKeyUsage). extensionValue is encoded as an
      array of CBOR ints (see Section 9.11), or unwrapped CBOR OID tags
      [RFC9090], where each int or OID encodes a key usage purpose.  If
      the array contains a single KeyPurposeId, the array is omitted.

      KeyPurposeId = int / ~oid
      ExtKeyUsageSyntax = [ 2* KeyPurposeId ] / KeyPurposeId

   *  Inhibit anyPolicy (inhibitAnyPolicy). extensionValue is encoded as
      follows:

      InhibitAnyPolicy = uint

   CBOR encoding of the following extension values are partly supported:

   *  Subject Alternative Name (subjectAltName).  If the subject
      alternative name only contains general names registered in
      Section 9.12 the extension value can be CBOR encoded.



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      extensionValue is encoded as an array of (int, any) pairs where
      each pair encodes a general name (see Section 9.12).  If
      subjectAltName contains exactly one dNSName, the array and the int
      are omitted and extensionValue is the dNSName encoded as a CBOR
      text string.  In addition to the general names defined in
      [RFC5280], the otherName with type-id id-on-hardwareModuleName,
      id-on-SmtpUTF8Mailbox and id-on-MACAddress haven been given their
      own int; such otherName are encoded as follows:

      -  For id-on-hardwareModuleName, the value is a CBOR array [
         hwType: ~oid, hwSerialNum: bytes ] as specified in [RFC4108].

      -  For id-on-SmtpUTF8Mailbox, the value is a CBOR text as
         specified in [RFC8398].

      -  For id-on-MACAddress, the value is a CBOR byte string
         containing 6 octets for EUI-48 and 8 octets for EUI-64 as
         specified in [I-D.ietf-lamps-macaddress-on].

      GeneralName = ( GeneralNameType : int, GeneralNameValue : any )
      GeneralNames = [ + GeneralName ]
      SubjectAltName = GeneralNames / text

   *  Issuer Alternative Name (issuerAltName). extensionValue is encoded
      exactly like subjectAltName.

      IssuerAltName  = GeneralNames / text

   *  CRL Distribution Points (cRLDistributionPoints).  If all
      DistributionPoint elements contains the distributionPoint with
      fullName choice of uniformResourceIdentifier, optional reasons,
      and optional cRLIssuer with one directoryName, the extension value
      can be CBOR encoded.  The 'reasons' BIT STRING is interpreted as
      an unsigned integer in network byte order and encoded as a CBOR
      int.  If the CRLDistributionPoints consists of only one
      DistributionPointName, which in turn has only the fullName field
      of type CBOR text, it shall be encoded as CBOR text, otherwise as
      CBOR array.

      DistributionPointName = [
        fullName  [ 2 * text ] / text,
        reasons   uint / null,
        cRLIssuer Name / null,
      ]

      CRLDistributionPoints = [ + DistributionPointName ] / text





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   *  Freshest CRL (freshestCRL). extensionValue is encoded exactly like
      cRLDistributionPoints.

      FreshestCRL = CRLDistributionPoints

   *  Authority Information Access (authorityInfoAccess).  If all the
      GeneralNames in authorityInfoAccess are of type
      uniformResourceIdentifier, the extension value can be CBOR
      encoded.  Each accessMethod is encoded as a CBOR int (see
      Section 9.10) or an unwrapped CBOR OID tag [RFC9090].  The
      uniformResourceIdentifiers are encoded as CBOR text strings.

      AccessDescription = ( accessMethod: int / ~oid , uri: text )
      AuthorityInfoAccessSyntax = [ + AccessDescription ]

   *  Subject Information Access (subjectInfoAccess).  Encoded exactly
      like authorityInfoAccess.

      SubjectInfoAccessSyntax = AuthorityInfoAccessSyntax

   *  Authority Key Identifier (authorityKeyIdentifier).  If the
      authority key identifier contains all of keyIdentifier,
      certIssuer, and certSerialNumber or if only keyIdentifier is
      present the extension value can be CBOR encoded.  If all three are
      present a CBOR array is used, if only keyIdentifier is present,
      the array is omitted:

      KeyIdentifierArray = [
        keyIdentifier: KeyIdentifier,
        authorityCertIssuer: GeneralNames,
        authorityCertSerialNumber: CertificateSerialNumber
      ]
      AuthorityKeyIdentifier = KeyIdentifierArray / KeyIdentifier

   *  Certificate Policies (certificatePolicies).  If noticeRef is not
      used and any explicitText are encoded as UTF8String, the extension
      value can be CBOR encoded.  OIDs registered in Section 9.8 are
      encoded as an int.  The policyQualifierId is encoded as an CBOR
      int (see Section 9.9) or an unwrapped CBOR OID tag [RFC9090].

      PolicyIdentifier = int / ~oid
      PolicyQualifierInfo = (
        policyQualifierId: int / ~oid,
        qualifier: text,
      )
      CertificatePolicies = [
        + ( PolicyIdentifier, [ * PolicyQualifierInfo ] )
      ]



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   *  Name Constraints (nameConstraints).  If the name constraints only
      contain general names registered in Section 9.12 the extension
      value can be CBOR encoded.  C509 uses the same additions and
      restrictions as defined in Section 4.2.1.10 of [RFC5280].  Note
      that the minimum and maximum fields are not used and therefore
      omitted.  For IPv4 addresses, the iPAddress field MUST contain
      five octets and for IPv6 addresses, the field MUST contain 17
      octets, where the last octet indicates the number of bits in the
      netmask.  As an example, the address block 192.0.2.0/24 is encoded
      as C0 00 02 00 18 instead of C0 00 02 00 FF FF FF 00 as in the DER
      encoding.

      GeneralSubtrees = [ + GeneralName ]
      NameConstraints = [
        permittedSubtrees: GeneralSubtrees / null,
        excludedSubtrees: GeneralSubtrees / null,
      ]

   *  Subject Directory Attributes (subjectDirectoryAttributes).
      Encoded as attributes in issuer and subject with the difference
      that there can be more than one attributeValue.

      RDNAttributes = (( attributeType: int,
                         attributeValue: [ + SpecialText] ) //
                       ( attributeType: ~oid, attributeValue: [+ bytes] ))
      SubjectDirectoryAttributes = [ + RDNAttributes ]

   *  AS Identifiers (id-pe-autonomousSysIds).  The X.509 extension AS
      Identifiers is specified in [RFC3779].  If rdi is not present, the
      extension value can be CBOR encoded.  Each ASId is encoded as a
      CBOR uint.  With the exception of the first ASId, the ASid is
      encoded as the difference to the previous ASid.

      ASIdOrRange = uint / [min:uint, max:uint]
      ASIdentifiers = [ + ASIdOrRange ] / null

   *  AS Identifiers v2 (id-pe-autonomousSysIds-v2).  The X.509
      extension AS Identifiers v2 is specified in [RFC8360].  The
      extension value is encoded exactly like in the extension "AS
      Identifiers".

   *  IPAddrBlocks (id-pe-ipAddrBlocks).  The X.509 extension
      IPAddrBlocks is specified in [RFC3779].  Each AddressPrefix is
      encoded as a CBOR bytes string (without the unused bits octet)
      followed by the number of unused bits encoded as a CBOR uint.
      Each AddressRange is encoded as an array of two CBOR byte strings.
      The unused bits for min and max are omitted, but the unused bits
      in max IPAddress are set to one.  With the exception of the first



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      Address, if the byte string has the same length as the previous
      Address, the Address is encoded as a uint with the difference to
      the previous Address.  It should be noted that using address
      differences for compactness prevents encoding an address range
      larger than 2^64 - 1 corresponding to the CBOR integer max value.

      Address = bytes
      AddressPrefix = [ unusedBits: uint, Address ]
      AddressRange = [ min: Address, max: Address ]
      IPAddressOrRange = AddressPrefix / AddressRange
      IPAddressChoice = [ + IPAddressOrRange ] / null
      IPAddressFamily = (AFI: uint, SAFI: uint / null, IPAddressChoice)
      IPAddrBlocks = [ + IPAddressFamily ]

   *  IPAddrBlocks v2 (id-pe-ipAddrBlocks-v2).  The X.509 extension
      IPAddrBlocks v2 is specified in [RFC8360].  The extension value is
      encoded exactly like in the extension "IPAddrBlocks".

   *  Signed Certificate Timestamp (Certificate Transparency).  If all
      the SCTs are version v1 [RFC6962], and there are no SCT
      extensions, the extension value can be CBOR encoded.  Other
      versions of SCT are out of scope for this document.  LogIDs are
      encoded as CBOR byte strings, the timestamp is encoded as a CBOR
      uint (milliseconds since validityNotBefore), and the signature is
      encoded with an (AlgorithmIdentifier, any) pair in the same way as
      issuerSignatureAlgorithm and issuerSignatureValue.

      SignedCertificateTimestamp = (
        logID: bytes,
        timestamp: int,
        sigAlg: AlgorithmIdentifier,
        sigValue: any,
      )
      SignedCertificateTimestamps = [ + SignedCertificateTimestamp ]

   *  OCSP No Check (id-pkix-ocsp-nocheck).  If the extension value is
      NULL, it can be CBOR encoded.  The CBOR encoded extensionValue is
      the value null.

   *  Precertificate Signing Certificate.  The CBOR encoded
      extensionValue is the value null.

   *  TLS Features (id-pe-tlsfeature).  The extensionValue is encoded as
      an array of integers, where each integer represents a TLS
      extension.

      TLSFeatures = [* feature: uint]




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3.3.1.  Example Encoding of Extensions

   The examples below use values from Section 9.7, Section 9.11, and
   Section 9.12:

   *  A critical basicConstraints ('cA' = true) without
      pathLenConstraint is encoded as the two CBOR ints -4, -1.

   *  A non-critical keyUsage with digitalSignature (0), nonRepudiation
      (1), keyEncipherment (2) and keyAgreement (4) asserted is encoded
      as the two CBOR ints 2, 23 (2^0 + 2^1 + 2^2 + 2^4 = 23).

   *  A non-critical extKeyUsage containing id-kp-codeSigning and id-kp-
      OCSPSigning is encoded as the CBOR int 8 followed by the CBOR
      array [ 3, 9 ].

   *  A non-critical subjectAltName containing only the dNSName
      example.com is encoded as the CBOR int 3 followed by the CBOR text
      string "example.com".

   Thus, the extension field of a certificate containing all of the
   above extensions in the given order would be encoded as the CBOR
   array [ -4, -1, 2, 23, 8, [ 3, 9 ], 3, "example.com" ].

3.4.  COSE Header Parameters

   The formatting and processing for c5b, c5c, c5t, and c5u, defined in
   Table 1 below, are similar to x5bag, x5chain, x5t, x5u defined in
   [RFC9360] except that the certificates are C509 instead of DER-
   encoded X.509 and use a COSE_C509 structure instead of COSE_X509.

   The COSE_C509 structure used in c5b, c5c, and c5u is defined as:

   COSE_C509 = C509CertData / [ 2* C509CertData ]
   C509CertData = bytes .cborseq C509Certificate

   C509CertData thus includes the unwrapped CBOR sequence,
   ~C509Certificate.  The byte string encoding includes the length of
   each certificate which simplifies parsing.  See Appendix A.1.5 for an
   example.

   The COSE_C509 item has media type application/cose-c509-cert, see
   Section 9.16.1.  Different CoAP Content-Formats are defined depending
   on "usage" = "chain" or not, see Section 9.17.  Stored file formats
   are defined for the cases with/without ("usage" = "chain") with
   "magic numbers" TBD8/TBD6 using the reserved CBOR tag 55799 and the
   corresponding Content-Formats TBD15/TBD3, enveloped as described in
   Section 2.2 of [RFC9277].



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   The value type of c5t is the COSE_CertHash structure defined in
   [RFC9360], which contains the hash value of the C509 certificate
   calculated over ~C509Certificate.  Thus C509CertData contains all
   data necessary to calculate the thumbprint c5t.

   c5u provides an alternative way to identify an untrusted certificate
   chain by reference with a URI [RFC3986], encoded as a CBOR text
   string (media type application/cbor and CoAP Content-Format 60).  The
   referenced resource is a COSE_C509 item served with the application/
   cose-c509-cert media type ("usage" = "chain"), as described above.

   As the contents of c5b, c5c, c5t, and c5u are untrusted input, the
   header parameters can be in either the protected or unprotected
   header bucket.  The trust mechanism MUST process any certificates in
   the c5b, c5c, and c5u parameters as untrusted input.  The presence of
   a self-signed certificate in the parameter MUST NOT cause the update
   of the set of trust anchors without appropriate authorization.

      +======+=======+===============+=============================+
      | Name | Label | Value Type    | Description                 |
      +======+=======+===============+=============================+
      |  c5b | 24    | COSE_C509     | An unordered bag of C509    |
      |      |       |               | certificates                |
      +------+-------+---------------+-----------------------------+
      |  c5c | 25    | COSE_C509     | An ordered chain of C509    |
      |      |       |               | certificates                |
      +------+-------+---------------+-----------------------------+
      |  c5t | 22    | COSE_CertHash | Hash of a ~C509Certificate  |
      +------+-------+---------------+-----------------------------+
      |  c5u | 23    | uri           | URI pointing to a COSE_C509 |
      |      |       |               | containing an ordered chain |
      |      |       |               | of certificates             |
      +------+-------+---------------+-----------------------------+

                     Table 1: COSE Header Parameters

   Note that certificates can also be identified with a 'kid' header
   parameter by storing 'kid' and the associated bag or chain in a
   dictionary.

3.5.  Private Key Structures

   Certificate management also makes use of data structures including
   private keys, see, e.g., [RFC7468].  This section defines the
   following CBOR encoded structures:






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   C509PrivateKey = [
      C509PrivateKeyType: int,
      subjectPrivateKeyAlgorithm: AlgorithmIdentifier,
      subjectPrivateKey: any,
   ]

   The field 'C509PrivateKeyType' indicates the type of the C509 private
   key.  Different types of C509 Private Key Structures can be defined,
   see Section 9.3.  Currently, two types are defined.  When
   C509PrivateKeyType = 0, the subjectPrivateKey is the CBOR byte string
   encoding of the PrivateKey OCTET STRING value field defined in
   [RFC5958].  When C509PrivateKeyType = 1, the subjectPrivateKey is a
   COSE_KEY structure containing a private key as defined in [RFC9052].
   Note that COSE_KEY might not be possible to use with all algorithms
   that have a C509 AlgorithmIdentifier defined.

   The C509PrivateKey item is served with the application/cose-
   c509-privkey media type, see Section 9.16.4, with corresponding CoAP
   Content-Format defined in Section 9.17.  A stored file format is
   defined with "magic number" TBD12 using the reserved CBOR tag 55799
   and the Content-Format TBD10, enveloped as described in Section 2.2
   of [RFC9277].

   C509PEM = [
      C509PrivateKey,
      COSE_C509 / null,
   ]

   The C509PEM item is served with the application/cose-c509-pem media
   type, see Section 9.16.5, with corresponding CoAP Content-Format
   defined in Section 9.17.  A stored file format is defined with "magic
   number" TBD13 using the reserved CBOR tag 55799 and the Content-
   Format TBD11, enveloped as described in Section 2.2 of [RFC9277].

3.6.  Deterministic Encoding

   In some use cases it is desirable to be able to specify a unique C509
   representation of a given X.509 certificate.

   While this specification requires the use of Deterministically
   Encoded CBOR (see Section 2), it is still possible to represent
   certain X.509 certificate fields in different ways.  This is a
   consequence of the extensibility of the C509 format where new
   encodings can be defined, for example to optimize extensions for
   which no special CBOR encoding have been previously defined.






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   Where there is support for a specific and a generic CBOR encoding,
   the specific CBOR encoding MUST be used.  For example, when there is
   support for specific CBOR encoding of an extension, as specified in
   Section 3.3 and the C509 Extensions Registry, it MUST be used.  In
   particular, when there is support for a specific otherName encoding
   (negative integer value in C509 General Names Registry) it MUST be
   used.

   Native C509 certificates MUST only use specific CBOR encoded fields.
   However, when decoding a non-native C509 certificates, the decoder
   may need to support, for example, (extensionID: ~oid, extensionValue:
   bytes / [bytes])-encoding of an extension for which there is an
   (extensionID:int, extensionValue:Defined)-encoding.  One reason is
   that the certificate was issued before the specific CBOR extension
   was registered.

3.7.  C509 Name in TLS and DTLS

   In TLS and DTLS, the subject of trusted authory may be sent to the
   peer to help it selecting the certificate chain, as in the
   CertificateAuthoritiesExtension in [RFC8446], in the
   certificate_authorities field of CertificateRequest in [RFC5246], or
   in the TrustedAuthorities in [RFC6066].  For such usage in the TLS
   and DTLS, the C509 name is wrapped in a distinguished name [X.501]
   with exactly one RelativeDistinguishedName, which in turn contains
   exactly one AttributeTypeAndValue with the attribute C509Name.  The
   attribute value is the raw byte string of the encoded C509 Name as in
   Section 3.1.6.

   The attribute for C509 Name has the following structure:

      id-at-c509Name OBJECT IDENTIFIER ::=
        { TBD30 }

      c509Name ATTRIBUTE ::= {
        WITH SYNTAX C509Name
        SINGLE VALUE TRUE
        ID id-at-c509Name }

      C509Name ::= OCTET STRING

4.  C509 Certificate (Signing) Request

   This section defines the format of a C509 Certificate Request, also
   known as a C509 Certificate Signing Request (CSR), based on and
   compatible with [RFC2986], and reusing the formatting of C509
   certificates defined in Section 3.




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   The CDDL for the C509 Certificate Request is shown in Figure 2.  The
   fields have the same encoding as the corresponding fields of the C509
   Certificate, see Section 3.1.

   C509CertificateRequest = [
      TBSCertificateRequest,
      subjectSignatureValue: any,
   ]

   ; The elements of the following group are used in a CBOR Sequence:
   TBSCertificateRequest = (
      c509CertificateRequestType: int,
      subjectSignatureAlgorithm: AlgorithmIdentifier,
      subject: Name,
      subjectPublicKeyAlgorithm: AlgorithmIdentifier,
      subjectPublicKey: Defined,
      attributes: CRAttributes,
   )

   CRAttributes = [ * CRAttribute ]

   CRAttribute = (( attributeType: int, attributeValue: Defined ) //
                  ( attributeType: ~oid, attributeValue: bytes ))

                 Figure 2: CDDL for C509CertificateRequest.

   After verifying the subjectSignatureValue, the CA MAY transform the
   C509CertificateRequest into a [RFC2986] CertificationRequestInfo for
   compatibility with existing procedures and code.

   The media type of C509CertificateRequest is application/cose-
   c509-pkcs10, see Section 9.16.2, with corresponding CoAP Content-
   Format defined in Section 9.17.  The "magic number" TBD9 is defined
   using the reserved CBOR tag 55799 and the Content-Format TBD4,
   enveloped as described in Section 2.2 of [RFC9277].

4.1.  Certificate Request Types

   Two types of C509 Certificate Requests are defined, both using the
   same CBOR encoding and differing only in what is being signed, see
   Section 9.2.  The C509 Certificate Request can either be an
   invertible CBOR re-encoding of a DER-encoded certification request
   [RFC2986], or it can be natively signed where the signature is
   calculated over the CBOR encoding instead of the DER encoding.

   *  c509CertificateRequestType = 2.  This type indicates that the C509
      Certificate Request is natively signed, i.e., that
      subjectSignatureValue contains the signature over the CBOR



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      Sequence TBSCertificateRequest, see Figure 2.  This encoding
      removes the need for ASN.1 and DER parsing, and re-encoding in the
      requesting party.

   *  c509CertificateRequestType = 3.  This type indicates that the C509
      Certificate Request is a CBOR re-encoded RFC 2986 certification
      request, as defined in Section 4.  This encoding is backwards
      compatible with legacy RFC 2986 certification requests, and
      enables a reduced transport overhead.

   The type of certificate issued after the request is decided by the
   application.  The default type of issued certificate in case of C509
   is that c509CertificateType = c509CertificateRequestType.

   An implementation MAY only support certain values of
   c509CertificateRequestType.

4.2.  Subject Signature Algorithm

   subjectSignatureAlgorithm can be a signature algorithm or a non-
   signature proof-of-possession algorithm, e.g., as defined in
   [RFC6955].  In the case of [RFC6955], the signature is replaced by a
   MAC and requires a public Diffie-Hellman key of the verifier
   distributed out-of-band.  Both signature algorithms and non-signature
   proof-of-possession algorithms are listed in the C509 Signature
   Algorithms Registry, see Section 9.13.  The non-signature roof-of-
   possession algorithms with SHA-2 and HMAC-SHA2 (see values 14-16 in
   Section 9.13) requires a signature value with syntax DhSigStatic
   defined as follows:

   DhSigStatic = MessageDigest / DhSigStaticType

   MessageDigest = bytes

   DhSigStaticType = [
     issuer: Name,
     serialNumber: CertificateSerialNumber
     hashValue: MessageDigest
   ]

   Note that a key agreement key pair may be used with a signature
   algorithm in a certificate request, see Appendix A.1.3.

4.3.  Certificate Request Attributes

   The 'attributes' field specifies the attributes contained in a
   certificate request.  The 'attributes' field with no GeneralAttribute
   SHALL be encoded as an empty CBOR array.



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   The remainder of this section specifies CBOR encoded attributes for
   Certificate Requests.

4.3.1.  Extension Request

   The X.509 attribute "Extension Request" is defined in [RFC2985].  The
   'attributeValue' field has type Extensions as in Section 3.1.  An
   empty CBOR array indicates no extensions.

4.3.2.  Challenge Password

   The X.509 attribute "Challenge Password" is defined in [RFC2985].
   The 'attributeValue' field has type ChallengePassword.  A UTF8 String
   is encoded as CBOR text, and a Printable String is tagged with number
   121 (alternative 0 as defined in Section 9.1 of
   [I-D.bormann-cbor-notable-tags]).  All other string types are not
   supported.  For certificate request type 2, only UTF8 String is
   allowed.

   ChallengePassword = text / #6.121(text)

4.3.3.  Private Key Possession Statement

   The X.509 attribute "Statement of Possession of a Private Key" is
   defined in [RFC9883].  The 'attributeValue' field has type
   PrivateKeyPossessionStatement.

   PrivateKeyPossessionStatement = [
     issuer: Name,
     serialNumber: CertificateSerialNumber,
     cert: C509Certificate / null,
   ]

4.4.  Certificate Request Template

   Enrollment over Secure Transport (EST, [RFC7030]) defines, and
   [I-D.ietf-lamps-rfc7030-csrattrs] clarifies, how an EST server can
   specify what it expects the EST client to include in a subsequent
   Certificate Signing Request (CSR).  Alternatively to the unstructured
   mechanism specified in [RFC7030], Appendix B of [RFC8295] describes
   an approach using a Certificate Request Template in response to a GET
   /csrattrs request by the EST client.  The EST server thus returns an
   Certificate Request-like object with various fields filled out, and
   other fields waiting to be filled in and a signature to be added by
   the EST client.






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   For C509 we follow the approach of [RFC8295].  The
   C509CertificateRequestTemplate is based on TBSCertificateRequest of
   the C509CertificateRequest, see Figure 2, but excludes the
   subjectSignatureValue field from the template since that needs no
   further specification.

   The C509 Certificate Request Template is shown in Figure 3.

   C509CertificateRequestTemplate = [
      c509CertificateRequestTemplateType: int,
      c509CertificateRequestType: [+ int] / undefined,
      subjectSignatureAlgorithm: [+ AlgorithmIdentifier] / undefined,
      subject: NameTemplate / undefined,
      subjectPublicKeyAlgorithm: [+ AlgorithmIdentifier] / undefined,
      subjectPublicKey: undefined
      extensionsRequest: ExtensionsTemplate / undefined,
   ]

   NameTemplate = [ * RDNAttributeTemplate ]

   RDNAttributeTemplate = (( attributeType: uint, minOccurs: uint, maxOccurs: uint,
                             attributeValue: SpecialText / undefined ) //
                           ( attributeType: ~oid, minOccurs: uint, maxOccurs: uint,
                             attributeValue: bytes / undefined ))

   ExtensionsTemplate = [ * ExtensionTemplate ]

   ExtensionTemplate = (( extensionID: uint, optional: bool, extensionValue: any ) //
                        ( extensionID: ~oid, optional: bool, extensionValue: bytes / undefined ))

             Figure 3: CDDL for C509CertificateRequestTemplate.

   Except as specified in this section, the fields have the same
   encoding as the corresponding fields of the TBSCertificateRequest,
   see Figure 2.  The specification of the template makes use of the
   CBOR simple value undefined (0xf7) to indicate fields to fill in.
   Consistent with this rule, note that the subjectPublicKey field
   always has the value undefined in the template.

   Different types of Certificate Request Templates can be defined (see
   Section 9.4), distinguished by the c509CertificateRequestTemplateType
   integer.  Each type may have its own CDDL structure.

   The presence of a Defined (non-undefined) value in a
   C509CertificateRequestTemplate indicates that the server expects the
   client to use that value in the certificate request.  If multiple
   AlgorithmIdentifier or c509CertificateRequestType values are present,
   the server expects the client to select one of them for use in the



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   Certificate Request.  The presence of an undefined value indicates
   that the client is expected to provide an appropriate value for that
   field.  For example, if the server includes a subjectAltName with a
   GeneralNameType iPAddress and a GeneralNameValue empty byte string,
   this means that the client SHOULD fill in a corresponding
   GeneralNameValue.

   For AttributeTemplate, the minOccurs and maxOccurs fields specify the
   minimal and maximal occurrences of attributes of the given
   attributeType; maximal shall not be less than minimal, and maximal
   shall be positive.  Negative attributeType is not allowed.

   For ExtensionTemplate, the field "optional" specifies whether an
   extension of the given extensionID is optional.  Negative extensionID
   is not allowed.

   The media type of C509CertificateRequestTemplate is application/cose-
   c509-crtemplate, see Section 9.16.3, with corresponding CoAP Content-
   Format defined in Section 9.17.  The "magic number" TBD18 is defined
   using the reserved CBOR tag 55799 and the Content-Format TBD19,
   enveloped as described in Section 2.2 of [RFC9277].

5.  C509 Processing and Certificate Issuance

   It is straightforward to integrate the C509 format into legacy X.509
   processing during certificate issuance.  C509 processing can be
   performed as an isolated function of the CA, or as a separate
   function trusted by the CA.

   The Certificate Request format defined in Section 4 follows the
   PKCS#10 format to enable a direct mapping to the certification
   request information, see Section 4.1 of [RFC2986].  The CA can make
   use of a Certificate Request Template defined in Section 4.4, for
   simplified configuration.

   When a certificate request is received, the CA, or function trusted
   by the CA, needs to perform some limited C509 processing and verify
   the proof-of-possession corresponding to the public key, before
   normal certificate generation can take place.

   In the reverse direction, in case c509CertificateType = 3 was
   requested, a separate C509 processing function can perform the
   conversion from a generated X.509 certificate to C509 as a bump-in-
   the-wire.  In case c509CertificateType = 2 was requested, the C509
   processing needs to be performed before signing the certificate, in
   which case a tighter integration with the CA may be needed.





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6.  Legacy Considerations

   C509 certificates can be deployed with legacy X.509 certificates and
   CA infrastructure.  An existing CA can continue to use its existing
   procedures and code for PKCS#10, and DER-encoded X.509 and only
   implement C509 as a thin processing layer on top.  When receiving a
   C509 CSR, the CA transforms it into a DER-encoded
   CertificationRequestInfo [RFC2986] and uses that with existing
   processes and code to produce an RFC 5280 DER-encoded X.509
   certificate.  The DER-encoded X.509 is then transformed into a C509
   certificate.  At any later point, the C509 certificate can be used to
   recreate the original X.509 data structure needed to verify the
   signature.

   For protocols like TLS/DTLS 1.2, where certificates are sent
   unencrypted, the actual encoding and compression can be done at
   different locations depending on the deployment setting.  For
   example, the mapping between C509 certificate and standard X.509
   certificate can take place in a 6LoWPAN border gateway, which allows
   the server side to stay unmodified.  This case gives the advantage of
   the low overhead of a C509 certificate over constrained wireless
   links.  The conversion to X.509 within a constrained IoT device will
   incur a computational overhead.  However, measured in energy, this is
   likely to be negligible compared to the reduced communication
   overhead.

   For the setting with constrained server and server-only
   authentication, the server only needs to be provisioned with the C509
   certificate and does not perform the conversion to X.509.  This
   option is viable when client authentication can be asserted by other
   means.

   For protocols like IKEv2, TLS/DTLS 1.3, and EDHOC, where certificates
   are encrypted, the proposed encoding needs to be done fully end-to-
   end, through adding the encoding/decoding functionality to the
   server.

7.  Expected Certificate Sizes

   The CBOR encoding of the sample certificate chains given in
   Appendix A results in the numbers shown in Figures 4 and 5.
   COSE_X509 is defined in [RFC9360] and COSE_C509 is defined in
   Section 9.15.  After RFC 7925 profiling, most duplicated information
   has been removed, and the remaining text strings are minimal in size.
   Therefore, the further size reduction reached with general
   compression mechanisms such as Brotli [RFC7932] will be small, mainly
   corresponding to making the ASN.1 encoding more compact.  CBOR
   encoding can however significantly compress RFC 7925 profiled



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   certificates.  In the examples with HTTPS certificate chains
   (www.ietf.org and tools.ietf.org) both C509 and Brotli perform well
   complementing each other.  C509 uses dedicated information to
   compress individual certificates, while Brotli can compress duplicate
   information in the entire chain.  Note that C509 certificates of type
   2 and 3 have the same size.  For Brotli, the Rust crate Brotli 3.3.0
   was used with compression level 11 and window size 22.

     +---------------------------------------+-----------+-----------+
     |                                       | COSE_X509 | COSE_C509 |
     +---------------------------------------+-----------+-----------+
     | RFC 7925 profiled IoT Certificate (1) |       317 |       142 |
     +---------------------------------------+-----------+-----------+
     | ECDSA HTTPS Certificate Chain (2)     |      2193 |      1397 |
     +---------------------------------------+-----------+-----------+
     | FN-DSA HTTPS Certificate Chain (2)    |      5127 |      4331 |
     +---------------------------------------+-----------+-----------+
     | ML-DSA HTTPS Certificate Chain (2)    |      9465 |      8669 |
     +---------------------------------------+-----------+-----------+
     | RSA HTTPS Certificate Chain (4)       |      5175 |      3937 |
     +---------------------------------------+-----------+-----------+

      Figure 4: Comparing Sizes of Certificate Chains in COSE.  Number
                  of bytes (length of certificate chain).

   +-------------------+-------+----------------+------+---------------+
   |                   | X.509 | X.509 + Brotli | C509 | C509 + Brotli |
   +-------------------+-------+----------------+------+---------------+
   | RFC 7925 Cert (1) |   327 |            324 |  152 |           170 |
   +-------------------+-------+----------------+------+---------------+
   | RPKI Cert (1)     | 20991 |           9134 | 8663 |          5671 |
   +-------------------+-------+----------------+------+---------------+
   | HTTPS Chain (2)   |  2204 |           1455 | 1417 |          1066 |
   +-------------------+-------+----------------+------+---------------+
   | HTTPS Chain (4)   |  5190 |           3244 | 3961 |          2848 |
   +-------------------+-------+----------------+------+---------------+
   | HTTPS Bag (8)     | 11578 |           3979 | 8885 |          3522 |
   +-------------------+-------+----------------+------+---------------+

     Figure 5: Comparing Sizes of Certificate Chains with TLS.  Number
        of bytes (length of certificate chain).  X.509 and C509 are
        Certificate messages.  X.509 + Brotli and C509 + Brotli are
                      CompressedCertificate messages.








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8.  Security Considerations

   The CBOR encoding of X.509 certificates does not change the security
   assumptions needed when deploying standard X.509 certificates but
   decreases the number of fields transmitted, which reduces the risk
   for implementation errors.  The security considerations of [RFC5280]
   apply.

   The use of natively signed C509 certificates removes the need for
   ASN.1 encoding, which is a rich source of security vulnerabilities.

   Conversion between the certificate formats can be made in constant
   time to reduce risk of information leakage through side channels.

   The mechanism in this document does not reveal any additional
   information compared to X.509.  Because of the difference in size, it
   will be possible to detect that this profile is used.  The gateway
   solution described in Section 6 requires unencrypted certificates and
   is not recommended.

   Any issues with decoding or parsing a C509 certificate should be
   handled exactly as how such errors would be handled for the
   corresponding X.509 certificate.  For example, a non-critical
   extension MAY be ignored if it is not recognized, see Section 4.2 of
   [RFC5280].

   As stated in Section 3.4, the contents of the COSE Header Parameters
   c5b, c5c, c5t, c5u is untrusted input that potentially may be
   verified using existing trust anchors or other trust establishment
   mechanism out of scope of this document.  Similar security
   considerations as x5bag, x5chain, x5t and x5u applies, see [RFC9360].
   Security considerations of the COSE protected and unprotected headers
   is discussed in [RFC9052].

9.  IANA Considerations

   This document creates several new registries in the new registry
   group "CBOR Encoded X.509 (C509) Parameters".  For all items, the
   'Reference' field points to this document.

   The expert reviewers for the registries defined in this document are
   expected to ensure that the usage solves a valid use case that could
   not be solved better in a different way, that it is not going to
   duplicate an entry that is already registered, and that the
   registered point is likely to be used in deployments.  They are
   furthermore expected to check the clarity of purpose and use of the
   requested code points.  Experts should take into account the expected
   usage of entries when approving point assignment, and the length of



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   the encoded value should be weighed against the number of code points
   left that encode to that size and how constrained the systems it will
   be used on are.  Values in the interval [-24, 23] have a 1-byte
   encoding, other values in the interval [-256, 255] have a 2-byte
   encoding, and the remaining values in the interval [-65536, 65535]
   have a 3-byte encoding.

   All assignments according to "IETF Review with Expert Review" are
   made on a "IETF Review" basis per Section 4.8 of [RFC8126] with
   "Expert Review" additionally required per Section 4.5 of [RFC8126].
   The procedure for early IANA allocation of "standards track code
   points" defined in [RFC7120] also applies.  When such a procedure is
   used, IANA will ask the designated expert(s) to approve the early
   allocation before registration.  In addition, working group chairs
   are encouraged to consult the expert(s) early during the process
   outlined in Section 3.1 of [RFC7120].

9.1.  C509 Certificate Types Registry

   IANA has created a new registry titled "C509 Certificate Types" in
   the new registry group "CBOR Encoded X.509 (C509) Parameters".  The
   fields of the registry are Value, Description, and Reference, where
   Value is an integer, and the other columns are text strings.  It is
   mandatory to specify content in all columns.  For values in the
   interval [-24, 23], the registration procedure is "IETF Review with
   Expert Review".  For all other values, the registration procedure is
   "Expert Review".  The initial contents of the registry are (see
   Section 3.1.1):

           +-------+-------------------------------------------+
           | Value | Description                               |
           +=======+===========================================+
           |     0 | Reserved                                  |
           +-------+-------------------------------------------+
           |     1 | Reserved                                  |
           +-------+-------------------------------------------+
           |     2 | Natively Signed C509 Certificate          |
           +-------+-------------------------------------------+
           |     3 | CBOR Re-encoded X.509 v3 Certificate      |
           +-------+-------------------------------------------+

                      Figure 6: C509 Certificate Types









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9.2.  C509 Certificate Request Types Registry

   IANA has created a new registry titled "C509 Certificate Request
   Types" in the new registry group "CBOR Encoded X.509 (C509)
   Parameters".  The fields of the registry are Value, Description, and
   Reference, where Value is an integer, and the other columns are text
   strings.  All columns are mandatory.  For values in the interval
   [-24, 23] the registration procedure is "IETF Review with Expert
   Review".  For all other values the registration procedure is "Expert
   Review".  The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Description                                               |
   +=======+===========================================================+
   |     0 | Reserved                                                  |
   +-------+-----------------------------------------------------------+
   |     1 | Reserved                                                  |
   +-------+-----------------------------------------------------------+
   |     2 | Natively Signed C509 Certificate Request.                 |
   +-------+-----------------------------------------------------------+
   |     3 | CBOR re-encoding of RFC 2986 certification request.       |
   +-------+-----------------------------------------------------------+

                  Figure 7: C509 Certificate Request Types

9.3.  C509 Private Key Types Registry

   IANA has created a new registry titled "C509 Private Key Types" in
   the new registry group "CBOR Encoded X.509 (C509) Parameters".  The
   fields of the registry are Value, Comments, and subjectPrivateKey,
   and Reference, where Value is an integer, and the other columns are
   text strings.  All columns are mandatory.  For values in the interval
   [-24, 23] the registration procedure is "IETF Review with Expert
   Review".  For all other values the registration procedure is "Expert
   Review".  The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Private Key Types                                         |
   +=======+===========================================================+
   |     0 | Comments:          Asymmetric Key Package (RFC 5958)      |
   |       | subjectPrivateKey: bytes                                  |
   +-------+-----------------------------------------------------------+
   |     1 | Comments:          COSE Key Object (RFC 9052)             |
   |       | subjectPrivateKey: COSE_Key                               |
   +-------+-----------------------------------------------------------+

                      Figure 8: C509 Private Key Types




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9.4.  C509 Certificate Request Templates Types Registry

   IANA has created a new registry titled "C509 Certificate Request
   Templates Types" in the new registry group "CBOR Encoded X.509 (C509)
   Parameters".  The columns of the registry are Value, Description, and
   Reference, where Value is an integer, and the other columns are text
   strings.  All columns are mandatory.  For values in the interval
   [-24, 23] the registration procedure is "IETF Review" and "Expert
   Review".  For all other values the registration procedure is "Expert
   Review".  The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Description                                               |
   +=======+===========================================================+
   |     0 | Simple C509 Certificate Request Template                  |
   +-------+-----------------------------------------------------------+

             Figure 9: C509 Certificate Request Templates Types

9.5.  C509 RDN Attributes Registry

   IANA has created a new registry titled "C509 RDN Attributes" in the
   new registry group "CBOR Encoded X.509 (C509) Parameters".  The
   fields of the registry are Value, Name, Identifiers, OID, DER,
   Comments and Reference, where Value is a non-negative integer, and
   the other columns are text strings.  Name and Identifiers are
   informal descriptions.  The fields Name, OID, and DER are mandatory.
   For values in the interval [0, 23] the registration procedure is
   "IETF Review with Expert Review".  Values ≥ 32768 are reserved for
   Private Use. For all other values the registration procedure is
   "Expert Review".  Name and Identifiers are informal descriptions.  If
   OID is present, the OID is given in dotted decimal representation,
   and the DER column contains the hex string of the DER-encoded OID
   [X.690].

   The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | RDN Attribute                                             |
   +=======+===========================================================+
   |     0 | Name:            Email Address                            |
   |       | Identifiers:     emailAddress, e-mailAddress              |
   |       | OID:             1.2.840.113549.1.9.1                     |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 01         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            Common Name                              |
   |       | Identifiers:     commonName, cn                           |



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   |       | OID:             2.5.4.3                                  |
   |       | DER:             06 03 55 04 03                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Surname                                  |
   |       | Identifiers:     surname, sn                              |
   |       | OID:             2.5.4.4                                  |
   |       | DER:             06 03 55 04 04                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Serial Number                            |
   |       | Identifiers:     serialNumber                             |
   |       | OID:             2.5.4.5                                  |
   |       | DER:             06 03 55 04 05                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Country                                  |
   |       | Identifiers:     countryName, c                           |
   |       | OID:             2.5.4.6                                  |
   |       | DER:             06 03 55 04 06                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            Locality                                 |
   |       | Identifiers:     localityName, locality, l                |
   |       | OID:             2.5.4.7                                  |
   |       | DER:             06 03 55 04 07                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            State or Province                        |
   |       | Identifiers:     stateOrProvinceName, st                  |
   |       | OID:             2.5.4.8                                  |
   |       | DER:             06 03 55 04 08                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Street Address                           |
   |       | Identifiers:     streetAddress, street                    |
   |       | OID:             2.5.4.9                                  |
   |       | DER:             06 03 55 04 09                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Organization                             |
   |       | Identifiers:     organizationName, o                      |
   |       | OID:             2.5.4.10                                 |
   |       | DER:             06 03 55 04 0A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Organizational Unit                      |
   |       | Identifiers:     organizationalUnitName, ou               |



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   |       | OID:             2.5.4.11                                 |
   |       | DER:             06 03 55 04 0B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Title                                    |
   |       | Identifiers:     title                                    |
   |       | OID:             2.5.4.12                                 |
   |       | DER:             06 03 55 04 0C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Business Category                        |
   |       | Identifiers:     businessCategory                         |
   |       | OID:             2.5.4.15                                 |
   |       | DER:             06 03 55 04 0F                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    12 | Name:            Postal Code                              |
   |       | Identifiers:     postalCode                               |
   |       | OID:             2.5.4.17                                 |
   |       | DER:             06 03 55 04 11                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            Given Name                               |
   |       | Identifiers:     givenName                                |
   |       | OID:             2.5.4.42                                 |
   |       | DER:             06 03 55 04 2A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:            Initials                                 |
   |       | Identifiers:     initials                                 |
   |       | OID:             2.5.4.43                                 |
   |       | DER:             06 03 55 04 2B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15 | Name:            Generation Qualifier                     |
   |       | Identifiers:     generationQualifier                      |
   |       | OID:             2.5.4.44                                 |
   |       | DER:             06 03 55 04 2C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | Name:            DN Qualifier                             |
   |       | Identifiers:     dnQualifier                              |
   |       | OID:             2.5.4.46                                 |
   |       | DER:             06 03 55 04 2E                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Name:            Pseudonym                                |
   |       | Identifiers:     pseudonym                                |



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   |       | OID:             2.5.4.65                                 |
   |       | DER:             06 03 55 04 41                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    18 | Name:            Organization Identifier                  |
   |       | Identifiers:     organizationIdentifier                   |
   |       | OID:             2.5.4.97                                 |
   |       | DER:             06 03 55 04 61                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    19 | Name:            Inc. Locality                            |
   |       | Identifiers:     jurisdictionOfIncorporationLocalityName  |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.1                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 01   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    20 | Name:            Inc. State or Province                   |
   |       | Identifiers:     jurisdictionOfIncorporation              |
   |       |                  StateOrProvinceName                      |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.2                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 02   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    21 | Name:            Inc. Country                             |
   |       | Identifiers:     jurisdictionOfIncorporationCountryName   |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.3                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 03   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    22 | Name:            Domain Component                         |
   |       | Identifiers:     domainComponent, dc                      |
   |       | OID:             0.9.2342.19200300.100.1.25               |
   |       | DER:             06 0A 09 92 26 89 93 F2 2C 64 01 19      |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    25 | Name:            Name                                     |
   |       | Identifiers:     name                                     |
   |       | OID:             2.5.4.41                                 |
   |       | DER:             06 03 55 04 29                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    26 | Name:            Telephone Number                         |
   |       | Identifiers:     telephoneNumber                          |
   |       | OID:             2.5.4.20                                 |
   |       | DER:             06 03 55 04 14                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    27 | Name:            Directory Management Domain Name         |



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   |       | Identifiers:     dmdName                                  |
   |       | OID:             2.5.4.54                                 |
   |       | DER:             06 03 55 04 36                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    28 | Name:            userid                                   |
   |       | Identifiers:     uid                                      |
   |       | OID:             0.9.2342.19200300.100.1.1                |
   |       | DER:             06 0A 09 92 26 89 93 F2 2C 64 01 01      |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    29 | Name:            Unstructured Name                        |
   |       | Identifiers:     unstructuredName                         |
   |       | OID:             1.2.840.113549.1.9.2                     |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 02         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    30 | Name:            Unstructured Address                     |
   |       | Identifiers:     unstructuredAddress                      |
   |       | OID:             1.2.840.113549.1.9.8                     |
   |       | DER:             06 0A 2A 86 48 86 F7 0D 01 09 08 00      |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                       Figure 10: C509 RDN Attributes

9.6.  C509 CR Attributes Registry

   IANA has created a new registry titled "C509 CR Attributes" in the
   new registry group "CBOR Encoded X.509 (C509) Parameters".  The
   fields of the registry are Value, Name, Identifiers, OID, DER,
   Comments, attributeValue, and Reference, where Value is an integer,
   and the other columns are text strings.  Name and Identifiers are
   informal descriptions.  The fields Name, OID, and DER are mandatory.
   For values in the interval [-24, 23] the registration procedure is
   "IETF Review with Expert Review".  Values ≥ 32768 are reserved for
   Private Use. For all other values the registration procedure is
   "Expert Review".  Name and Identifiers are informal descriptions.  If
   OID is present, the OID is given in dotted decimal representation,
   and the DER column contains the hex string of the DER-encoded OID
   [X.690].

   The initial contents of the registry are:








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   +-------+-----------------------------------------------------------+
   | Value | CR Attribute                                              |
   +=======+===========================================================+
   |     0 | Name:            Extension Request                        |
   |       | Identifiers:     extensionRequest                         |
   |       | OID:             1.2.840.113549.1.9.14                    |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 0E         |
   |       | Comments:        RFC 2985                                 |
   |       | attributeValue:  Extensions                               |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            Challenge Password                       |
   |       | Identifiers:     challengePassword                        |
   |       | OID:             1.2.840.113549.1.9.7                     |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 07         |
   |       | Comments:        RFC 2985                                 |
   |       |                  Negative value for Printable String,     |
   |       |                  and positive value for UTF8 String       |
   |       | attributeValue:  ChallengePassword                        |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Private Key Possession Statement         |
   |       | Identifiers:     privateKeyPossessionStatement            |
   |       | OID:             1.3.6.1.4.1.22112.2.1                    |
   |       | DER:             06 0A 2B 06 01 04 01 81 AC 60 02 01      |
   |       | Comments:        RFC 9883                                 |
   |       | attributeValue:  PrivateKeyPossessionStatement            |
   +-------+-----------------------------------------------------------+

                        Figure 11: C509 CRAttributes

9.7.  C509 Extensions Registry

   IANA has created a new registry titled "C509 Extensions Registry" in
   the new registry group "CBOR Encoded X.509 (C509) Parameters".  The
   fields of the registry are Value, Name, Identifiers, OID, DER,
   Comments, extensionValue, and Reference, where Value is a positive
   integer, and the other columns are text strings.  The fields Name,
   OID, DER, abd extensionValue are mandatory.  For values in the
   interval [1, 23] the registration procedure is "IETF Review with
   Expert Review".  Values ≥ 32768 are reserved for Private Use. For all
   other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Extension                                                 |
   +=======+===========================================================+
   |     1 | Name:            Subject Key Identifier                   |
   |       | Identifiers:     subjectKeyIdentifier                     |
   |       | OID:             2.5.29.14                                |



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   |       | DER:             06 03 55 1D 0E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectKeyIdentifier                     |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Key Usage                                |
   |       | Identifiers:     keyUsage                                 |
   |       | OID:             2.5.29.15                                |
   |       | DER:             06 03 55 1D 0F                           |
   |       | Comments:                                                 |
   |       | AttributeValue:  KeyUsage                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Subject Alternative Name                 |
   |       | Identifiers:     subjectAltName                           |
   |       | OID:             2.5.29.17                                |
   |       | DER:             06 03 55 1D 11                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectAltName                           |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Basic Constraints                        |
   |       | Identifiers:     basicConstraints                         |
   |       | OID:             2.5.29.19                                |
   |       | DER:             06 03 55 1D 13                           |
   |       | Comments:                                                 |
   |       | extensionValue:  BasicConstraints                         |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            CRL Distribution Points                  |
   |       | Identifiers:     cRLDistributionPoints                    |
   |       | OID:             2.5.29.31                                |
   |       | DER:             06 03 55 1D 1F                           |
   |       | Comments:                                                 |
   |       | extensionValue:  CRLDistributionPoints                    |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            Certificate Policies                     |
   |       | Identifiers:     certificatePolicies                      |
   |       | OID:             2.5.29.32                                |
   |       | DER:             06 03 55 1D 20                           |
   |       | Comments:                                                 |
   |       | extensionValue:  CertificatePolicies                      |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Authority Key Identifier                 |
   |       | Identifiers:     authorityKeyIdentifier                   |
   |       | OID:             2.5.29.35                                |
   |       | DER:             06 03 55 1D 23                           |
   |       | Comments:                                                 |
   |       | extensionValue:  AuthorityKeyIdentifier                   |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Extended Key Usage                       |
   |       | Identifiers:     extKeyUsage                              |



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   |       | OID:             2.5.29.37                                |
   |       | DER:             06 03 55 1D 25                           |
   |       | Comments:                                                 |
   |       | extensionValue:  ExtKeyUsageSyntax                        |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Authority Information Access             |
   |       | Identifiers:     authorityInfoAccess                      |
   |       | OID:             1.3.6.1.5.5.7.1.1                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 01            |
   |       | Comments:                                                 |
   |       | extensionValue:  AuthorityInfoAccessSyntax                |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Signed Certificate Timestamp List        |
   |       | Identifiers:                                              |
   |       | OID:             1.3.6.1.4.1.11129.2.4.2                  |
   |       | DER:             06 0A 2B 06 01 04 01 D6 79 02 04 02      |
   |       | Comments:                                                 |
   |       | extensionValue:  SignedCertificateTimestamps              |
   +-------+-----------------------------------------------------------+
   |    24 | Name:            Subject Directory Attributes             |
   |       | Identifiers:     subjectDirectoryAttributes               |
   |       | OID:             2.5.29.9                                 |
   |       | DER:             06 03 55 1D 09                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectDirectoryAttributes               |
   +-------+-----------------------------------------------------------+
   |    25 | Name:            Issuer Alternative Name                  |
   |       | Identifiers:     issuerAltName                            |
   |       | OID:             2.5.29.18                                |
   |       | DER:             06 03 55 1D 12                           |
   |       | Comments:                                                 |
   |       | extensionValue:  IssuerAltName                            |
   +-------+-----------------------------------------------------------+
   |    26 | Name:            Name Constraints                         |
   |       | Identifiers:     nameConstraints                          |
   |       | OID:             2.5.29.30                                |
   |       | DER:             06 03 55 1D 1E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  NameConstraints                          |
   +-------+-----------------------------------------------------------+
   |    27 | Name:            Policy Mappings                          |
   |       | Identifiers:     policyMappings                           |
   |       | OID:             2.5.29.33                                |
   |       | DER:             06 03 55 1D 21                           |
   |       | Comments:                                                 |
   |       | extensionValue:  PolicyMappings                           |
   +-------+-----------------------------------------------------------+
   |    28 | Name:            Policy Constraints                       |



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   |       | Identifiers:     policyConstraints                        |
   |       | OID:             2.5.29.36                                |
   |       | DER:             06 03 55 1D 24                           |
   |       | Comments:                                                 |
   |       | extensionValue:  PolicyConstraints                        |
   +-------+-----------------------------------------------------------+
   |    29 | Name:            Freshest CRL                             |
   |       | Identifiers:     freshestCRL                              |
   |       | OID:             2.5.29.46                                |
   |       | DER:             06 03 55 1D 2E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  FreshestCRL                              |
   +-------+-----------------------------------------------------------+
   |    30 | Name:            Inhibit anyPolicy                        |
   |       | Identifiers:     inhibitAnyPolicy                         |
   |       | OID:             2.5.29.54                                |
   |       | DER:             06 03 55 1D 36                           |
   |       | Comments:                                                 |
   |       | extensionValue:  InhibitAnyPolicy                         |
   +-------+-----------------------------------------------------------+
   |    31 | Name:            Subject Information Access               |
   |       | Identifiers:     subjectInfoAccess                        |
   |       | OID:             1.3.6.1.5.5.7.1.11                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 0B            |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectInfoAccessSyntax                  |
   +-------+-----------------------------------------------------------+
   |    32 | Name:            IPAddrBlocks                             |
   |       | Identifiers:     id-pe-ipAddrBlocks                       |
   |       | OID:             1.3.6.1.5.5.7.1.7                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 07            |
   |       | Comments:        RFC 3779                                 |
   |       | extensionValue:  IPAddrBlocks                             |
   +-------+-----------------------------------------------------------+
   |    33 | Name:            AS Identifiers                           |
   |       | Identifiers:     id-pe-autonomousSysIds                   |
   |       | OID:             1.3.6.1.5.5.7.1.8                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 08            |
   |       | Comments:        RFC 3779                                 |
   |       | extensionValue:  ASIdentifiers                            |
   +-------+-----------------------------------------------------------+
   |    34 | Name:            IPAddrBlocks v2                          |
   |       | Identifiers:     id-pe-ipAddrBlocks-v2                    |
   |       | OID:             1.3.6.1.5.5.7.1.28                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 1C            |
   |       | Comments:        RFC 8360                                 |
   |       | extensionValue:  IPAddrBlocks                             |
   +-------+-----------------------------------------------------------+



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   |    35 | Name:            AS Identifiers v2                        |
   |       | Identifiers:     id-pe-autonomousSysIds-v2                |
   |       | OID:             1.3.6.1.5.5.7.1.29                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 1D            |
   |       | Comments:        RFC 8360                                 |
   |       | extensionValue:  ASIdentifiers                            |
   +-------+-----------------------------------------------------------+
   |    36 | Name:            OCSP No Check                            |
   |       | Identifiers:     id-pkix-ocsp-nocheck                     |
   |       | OID:             1.3.6.1.5.5.7.48.1.5                     |
   |       | DER:             06 09 2B 06 01 05 05 07 30 01 05         |
   |       | Comments:                                                 |
   |       | extensionValue:  null                                     |
   +-------+-----------------------------------------------------------+
   |    37 | Name:            Precertificate Signing Certificate       |
   |       | Identifiers:                                              |
   |       | OID:             1.3.6.1.4.1.11129.2.4.3                  |
   |       | DER:             06 0A 2B 06 01 04 01 D6 79 02 04 03      |
   |       | Comments:        RFC 6962                                 |
   |       | extensionValue:  null                                     |
   +-------+-----------------------------------------------------------+
   |    38 | Name:            TLS Features                             |
   |       | Identifiers:     id-pe-tlsfeature                         |
   |       | OID:             1.3.6.1.5.5.7.1.24                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 18            |
   |       | Comments:        RFC 7633                                 |
   |       | extensionValue:  TLSFeatures                              |
   +-------+-----------------------------------------------------------+

                         Figure 12: C509 Extensions

9.8.  C509 Certificate Policies Registry

   IANA has created a new registry titled "C509 Certificate Policies
   Registry" in the new registry group "CBOR Encoded X.509 (C509)
   Parameters".  The fields of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  The fields Name,
   OID, and DER are mandatory.  For values in the interval [-24, 23] the
   registration procedure is "IETF Review with Expert Review".  Values ≥
   32768 are reserved for Private Use. For all other values the
   registration procedure is "Expert Review".  The initial contents of
   the registry are:








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   +-------+-----------------------------------------------------------+
   | Value | Certificate Policy                                        |
   +=======+===========================================================+
   |     0 | Name:            Any Policy                               |
   |       | Identifiers:     anyPolicy                                |
   |       | OID:             2.5.29.32.0                              |
   |       | DER:             06 04 55 1D 20 00                        |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            Domain Validation (DV)                   |
   |       | Identifiers:     domain-validated                         |
   |       | OID:             2.23.140.1.2.1                           |
   |       | DER:             06 06 67 81 0C 01 02 01                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Organization Validation (OV)             |
   |       | Identifiers:     organization-validated                   |
   |       | OID:             2.23.140.1.2.2                           |
   |       | DER:             06 06 67 81 0C 01 02 02                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Individual Validation (IV)               |
   |       | Identifiers:     individual-validated                     |
   |       | OID:             2.23.140.1.2.3                           |
   |       | DER:             06 06 67 81 0C 01 02 03                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Extended Validation (EV)                 |
   |       | Identifiers:     ev-guidelines                            |
   |       | OID:             2.23.140.1.1                             |
   |       | DER:             06 05 67 81 0C 01 01                     |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Resource PKI (RPKI)                      |
   |       | Identifiers:     id-cp-ipAddr-asNumber                    |
   |       | OID:             1.3.6.1.5.5.7.14.2                       |
   |       | DER:             06 08 2B 06 01 05 05 07 0E 02            |
   |       | Comments:        RFC 3779                                 |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Resource PKI (RPKI) (Alternative)        |
   |       | Identifiers:     id-cp-ipAddr-asNumber-v2                 |
   |       | OID:             1.3.6.1.5.5.7.14.3                       |
   |       | DER:             06 08 2B 06 01 05 05 07 0E 03            |
   |       | Comments:        RFC 8360                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Remote SIM Provisioning Role             |
   |       |                  Certificate Issuer                       |
   |       | Identifiers:     id-rspRole-ci                            |



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   |       | OID:             2.23.146.1.2.1.0                         |
   |       | DER:             06 07 67 81 12 01 02 01 00               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Remote SIM Provisioning Role             |
   |       |                  eUICC                                    |
   |       | Identifiers:     id-rspRole-euicc                         |
   |       | OID:             2.23.146.1.2.1.1                         |
   |       | DER:             06 07 67 81 12 01 02 01 01               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    12 | Name:            Remote SIM Provisioning Role             |
   |       |                  eUICC Manufacturer                       |
   |       | Identifiers:     id-rspRole-eum                           |
   |       | OID:             2.23.146.1.2.1.2                         |
   |       | DER:             06 07 67 81 12 01 02 01 02               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DP+ TLS                               |
   |       | Identifiers:     id-rspRole-dp-tls                        |
   |       | OID:             2.23.146.1.2.1.3                         |
   |       | DER:             06 07 67 81 12 01 02 01 03               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DP+ Authentication                    |
   |       | Identifiers:     id-rspRole-dp-auth                       |
   |       | OID:             2.23.146.1.2.1.4                         |
   |       | DER:             06 07 67 81 12 01 02 01 04               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DP+ Profile Binding                   |
   |       | Identifiers:     id-rspRole-dp-pb                         |
   |       | OID:             2.23.146.1.2.1.5                         |
   |       | DER:             06 07 67 81 12 01 02 01 05               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DS TLS                                |
   |       | Identifiers:     id-rspRole-ds-tls                        |
   |       | OID:             2.23.146.1.2.1.6                         |
   |       | DER:             06 07 67 81 12 01 02 01 06               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Name:            Remote SIM Provisioning Role             |
   |       |                  SM-DS Authentication                     |



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   |       | Identifiers:     id-rspRole-ds-auth                       |
   |       | OID:             2.23.146.1.2.1.7                         |
   |       | DER:             06 07 67 81 12 01 02 01 07               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                    Figure 13: C509 Certificate Policies

9.9.  C509 Policies Qualifiers Registry

   IANA has created a new registry titled "C509 Policies Qualifiers
   Registry" in the new registry group "CBOR Encoded X.509 (C509)
   Parameters".  The fields of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  The fields Name,
   OID, and DER are mandatory.  For values in the interval [-24, 23] the
   registration procedure is "IETF Review with Expert Review".  Values ≥
   32768 are reserved for Private Use. For all other values the
   registration procedure is "Expert Review".  The initial contents of
   the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Certificate Policy                                        |
   +=======+===========================================================+
   |     1 | Name:            Certification Practice Statement         |
   |       | Identifiers:     id-qt-cps, cps                           |
   |       | OID:             1.3.6.1.5.5.7.2.1                        |
   |       | DER:             06 08 2B 06 01 05 05 07 02 01            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            User Notice                              |
   |       | Identifiers:     id-qt-unotice, unotice                   |
   |       | OID:             1.3.6.1.5.5.7.2.2                        |
   |       | DER:             06 08 2B 06 01 05 05 07 02 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                    Figure 14: C509 Policies Qualifiers

9.10.  C509 Information Access Registry

   IANA has created a new registry titled "C509 Information Access
   Registry" in the new registry group "CBOR Encoded X.509 (C509)
   Parameters".  The fields of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  The fields Name,
   OID, and DER are mandatory.  For values in the interval [-24, 23] the
   registration procedure is "IETF Review with Expert Review".  For all



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   other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Information Access                                        |
   +=======+===========================================================+
   |     1 | Name:            OCSP                                     |
   |       | Identifiers:     id-ad-ocsp, id-pkix-ocsp                 |
   |       | OID:             1.3.6.1.5.5.7.48.1                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 01            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            CA Issuers                               |
   |       | Identifiers:     id-ad-caIssuers, caIssuers               |
   |       | OID:             1.3.6.1.5.5.7.48.2                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Time Stamping                            |
   |       | Identifiers:     id-ad-timeStamping, timeStamping         |
   |       | OID:             1.3.6.1.5.5.7.48.3                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 03            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            CA Repository                            |
   |       | Identifiers:     id-ad-caRepository                       |
   |       | OID:             1.3.6.1.5.5.7.48.5                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 05            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            RPKI Manifest                            |
   |       | Identifiers:     id-ad-rpkiManifest                       |
   |       | OID:             1.3.6.1.5.5.7.48.10                      |
   |       | DER:             06 08 2B 06 01 05 05 07 30 0A            |
   |       | Comments:        RFC 6487                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Signed Object                            |
   |       | Identifiers:     id-ad-signedObject                       |
   |       | OID:             1.3.6.1.5.5.7.48.11                      |
   |       | DER:             06 08 2B 06 01 05 05 07 30 0B            |
   |       | Comments:        RFC 6487                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            RPKI Notify                              |
   |       | Identifiers:     id-ad-rpkiNotify                         |
   |       | OID:             1.3.6.1.5.5.7.48.13                      |
   |       | DER:             06 08 2B 06 01 05 05 07 30 0D            |
   |       | Comments:        RFC 8182                                 |
   +-------+-----------------------------------------------------------+



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                    Figure 15: C509 Information Accesses

9.11.  C509 Extended Key Usages Registry

   IANA has created a new registry titled "C509 Extended Key Usages
   Registry" in the new registry group "CBOR Encoded X.509 (C509)
   Parameters".  The fields of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  The fields Name,
   OID, and DER are mandatory.  For values in the interval [-24, 23] the
   registration procedure is "IETF Review with Expert Review".  Values ≥
   32768 are reserved for Private Use. For all other values the
   registration procedure is "Expert Review".  The initial contents of
   the registry are:

    +-------+---------------------------------------------------------+
    | Value | Extended Key Usage                                      |
    +=======+=========================================================+
    |     0 | Name:            Any Extended Key Usage                 |
    |       | Identifiers:     anyExtendedKeyUsage                    |
    |       | OID:             2.5.29.37.0                            |
    |       | DER:             06 04 55 1D 25 00                      |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     1 | Name:            TLS Server authentication              |
    |       | Identifiers:     id-kp-serverAuth                       |
    |       | OID:             1.3.6.1.5.5.7.3.1                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 01          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     2 | Name:            TLS Client Authentication              |
    |       | Identifiers:     id-kp-clientAuth                       |
    |       | OID:             1.3.6.1.5.5.7.3.2                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 02          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     3 | Name:            Code Signing                           |
    |       | Identifiers:     id-kp-codeSigning                      |
    |       | OID:             1.3.6.1.5.5.7.3.3                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 03          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     4 | Name:            Email protection (S/MIME)              |
    |       | Identifiers:     id-kp-emailProtection                  |
    |       | OID:             1.3.6.1.5.5.7.3.4                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 04          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+



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    |     8 | Name:            Time Stamping                          |
    |       | Identifiers:     id-kp-timeStamping, timestamping       |
    |       | OID:             1.3.6.1.5.5.7.3.8                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 08          |
    |       | Comments:                                               |
    +-------+---------------------------------------------------------+
    |     9 | Name:            OCSP Signing                           |
    |       | Identifiers:     id-kp-OCSPSigning                      |
    |       | OID:             1.3.6.1.5.5.7.3.9                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 09          |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |    10 | Name:            Kerberos PKINIT Client Auth            |
    |       | Identifiers:     id-pkinit-KPClientAuth                 |
    |       | OID:             1.3.6.1.5.2.3.4                        |
    |       | DER:             06 07 2B 06 01 05 02 03 04             |
    |       | Comments:        RFC 4556                               |
    +-------+---------------------------------------------------------+
    |    11 | Name:            Kerberos PKINIT KDC                    |
    |       | Identifiers:     id-pkinit-KPKdc                        |
    |       | OID:             1.3.6.1.5.2.3.5                        |
    |       | DER:             06 07 2B 06 01 05 02 03 05             |
    |       | Comments:        RFC 4556                               |
    +-------+---------------------------------------------------------+
    |    12 | Name:            SSH Client                             |
    |       | Identifiers:     id-kp-secureShellClient                |
    |       | OID:             1.3.6.1.5.5.7.3.21                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 15          |
    |       | Comments:        RFC 6187                               |
    +-------+---------------------------------------------------------+
    |    13 | Name:            SSH Server                             |
    |       | Identifiers:     id-kp-secureShellServer                |
    |       | OID:             1.3.6.1.5.5.7.3.22                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 16          |
    |       | Comments:        RFC 6187                               |
    +-------+---------------------------------------------------------+
    |    14 | Name:            Bundle Security                        |
    |       | Identifiers:     id-kp-bundleSecurity                   |
    |       | OID:             1.3.6.1.5.5.7.3.35                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 23          |
    |       | Comments:        RFC 9174                               |
    +-------+---------------------------------------------------------+
    |    15 | Name:            CMC Certification Authority            |
    |       | Identifiers:     id-kp-cmcCA                            |
    |       | OID:             1.3.6.1.5.5.7.3.27                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 1B          |
    |       | Comments:        RFC 6402                               |
    +-------+---------------------------------------------------------+



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    |    16 | Name:            CMC Registration Authority             |
    |       | Identifiers:     id-kp-cmcRA                            |
    |       | OID:             1.3.6.1.5.5.7.3.28                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 1C          |
    |       | Comments:        RFC 6402                               |
    +-------+---------------------------------------------------------+
    |    17 | Name:            CMC Archive Server                     |
    |       | Identifiers:     id-kp-cmcArchive                       |
    |       | OID:             1.3.6.1.5.5.7.3.29                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 1D          |
    |       | Comments:        RFC 6402                               |
    +-------+---------------------------------------------------------+
    |    18 | Name:            CMC Key Generation Authority           |
    |       | Identifiers:     id-kp-cmKGA                            |
    |       | OID:             1.3.6.1.5.5.7.3.32                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 20          |
    |       | Comments:        RFC 9480                               |
    +-------+---------------------------------------------------------+
    |    19 | Name:            Certificate Transparency               |
    |       | Identifiers:                                            |
    |       | OID:             1.3.6.1.4.1.11129.2.4.4                |
    |       | DER:             06 0A 2B 06 01 04 01 D6 79 02 04 04    |
    |       | Comments:        RFC 6962                               |
    +-------+---------------------------------------------------------+

                    Figure 16: C509 Extended Key Usages

9.12.  C509 General Names Registry

   IANA has created a new registry titled "C509 General Names Registry"
   in the new registry group "CBOR Encoded X.509 (C509) Parameters".
   The fields of the registry are Value, Name, Comments,
   GeneralNameValue, and Reference, where Value is an integer, and the
   other columns are text strings.  The fields Name and GeneralNameValue
   are mandatory.  For values in the interval [-24, 23] the registration
   procedure is "IETF Review with Expert Review".  For all other values
   the registration procedure is "Expert Review".  The initial contents
   of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | General Names                                             |
   +=======+===========================================================+
   |    -3 | Name:            otherName with MACAddress                |
   |       | Comments:        id-on-MACAddress                         |
   |       |                  (TBD90)                                  |
   |       |                  TBD91                                    |
   |       | Value:           bytes                                    |
   +-------+-----------------------------------------------------------+



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   |    -2 | Name:            otherName with SmtpUTF8Mailbox           |
   |       | Comments:        id-on-SmtpUTF8Mailbox                    |
   |       |                  (1.3.6.1.5.5.7.8.9)                      |
   |       |                  06 08 2B 06 01 05 05 07 08 09            |
   |       | GeneralNameValue:  text                                   |
   +-------+-----------------------------------------------------------+
   |    -1 | Name:            otherName with hardwareModuleName        |
   |       | Comments:        id-on-hardwareModuleName                 |
   |       |                  (1.3.6.1.5.5.7.8.4)                      |
   |       |                  06 08 2B 06 01 05 05 07 08 04            |
   |       | GeneralNameValue:  [ ~oid, bytes ]                        |
   +-------+-----------------------------------------------------------+
   |     0 | Name:            otherName                                |
   |       | Comments:                                                 |
   |       | GeneralNameValue:  [ ~oid, bytes ]                        |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            rfc822Name                               |
   |       | Comments:                                                 |
   |       | GeneralNameValue:  text                                   |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            dNSName                                  |
   |       | Comments:                                                 |
   |       | GeneralNameValue:  text                                   |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            directoryName                            |
   |       | Comments:                                                 |
   |       | GeneralNameValue:  Name                                   |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            uniformResourceIdentifier                |
   |       | Comments:                                                 |
   |       | GeneralNameValue:  text                                   |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            iPAddress                                |
   |       | Comments:                                                 |
   |       | GeneralNameValue:  bytes                                  |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            registeredID                             |
   |       | Comments:                                                 |
   |       | GeneralNameValue:  ~oid                                   |
   +-------+-----------------------------------------------------------+

                       Figure 17: C509 General Names









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9.13.  C509 Signature Algorithms Registry

   IANA has created a new registry titled "C509 Signature Algorithms" in
   the new registry group "CBOR Encoded X.509 (C509) Parameters".  The
   registry includes both signature algorithms and non-signature proof-
   of-possession algorithms.  The fields of the registry are Value,
   Name, Identifiers, OID, Parameters, DER, Comments, and Reference,
   where Value is an integer, and the other columns are text strings.
   The fields Name, OID, Parameters, and DER are mandatory.  Alignment
   with the value of public key algorithm MUST be considered, see
   instruction in Section 9.14.  For values in the interval [-24, 23]
   the registration procedure is "IETF Review with Expert Review".  For
   all other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | X.509 Signature Algorithms                                |
   +=======+===========================================================+
   |  -256 | Name:        RSASSA-PKCS1-v1_5 with SHA-1                 |
   |       | Identifiers: sha1-with-rsa-signature,                     |
   |       |              sha1WithRSAEncryption,                       |
   |       |              sha-1WithRSAEncryption                       |
   |       | OID:         1.2.840.113549.1.1.5                         |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0D 06 09 2A 86 48 86 F7 0D 01 01 05 05 00 |
   |       | Comments:    Don't use                                    |
   +-------+-----------------------------------------------------------+
   |  -255 | Name:        ECDSA with SHA-1                             |
   |       | Identifiers: ecdsa-with-SHA1                              |
   |       | OID:         1.2.840.10045.4.1                            |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 09 06 07 2A 86 48 CE 3D 04 01             |
   |       | Comments:    Don't use. See Section 3.2.2.                |
   +-------+-----------------------------------------------------------+
   |     0 | Name:        ECDSA with SHA-256                           |
   |       | Identifiers: ecdsa-with-SHA256                            |
   |       | OID:         1.2.840.10045.4.3.2                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 02          |
   |       | Comments:    See Section 3.2.2.                           |
   +-------+-----------------------------------------------------------+
   |     1 | Name:        ECDSA with SHA-384                           |
   |       | Identifiers: ecdsa-with-SHA384                            |
   |       | OID:         1.2.840.10045.4.3.3                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 03          |
   |       | Comments:    See Section 3.2.2.                           |
   +-------+-----------------------------------------------------------+



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   |     2 | Name:        ECDSA with SHA-512                           |
   |       | Identifiers: ecdsa-with-SHA512                            |
   |       | OID:         1.2.840.10045.4.3.4                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 04          |
   |       | Comments:    See Section 3.2.2.                           |
   +-------+-----------------------------------------------------------+
   |     3 | Name:        ECDSA with SHAKE128                          |
   |       | Identifiers: id-ecdsa-with-shake128                       |
   |       | OID:         1.3.6.1.5.5.7.6.32                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 20          |
   |       | Comments:    See Section 3.2.2.                           |
   +-------+-----------------------------------------------------------+
   |     4 | Name:        ECDSA with SHAKE256                          |
   |       | Identifiers: id-ecdsa-with-shake256                       |
   |       | OID:         1.3.6.1.5.5.7.6.33                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 21          |
   |       | Comments:    See Section 3.2.2.                           |
   +-------+-----------------------------------------------------------+
   |     5 | Name:        Unsigned                                     |
   |       | Identifiers: id-alg-unsigned                              |
   |       | OID:         1.3.6.1.5.5.7.6.36                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 24          |
   |       | Comments:    bytes of size 0                              |
   +-------+-----------------------------------------------------------+
   |    12 | Name:        Ed25519                                      |
   |       | Identifiers: id-Ed25519, id-EdDSA25519                    |
   |       | OID:         1.3.101.112                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 70                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:        Ed448                                        |
   |       | Identifiers: id-Ed448, id-EdDSA448                        |
   |       | OID:         1.3.101.113                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 71                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:        PoP with SHA-256 and HMAC-SHA256             |
   |       | Identifiers: sa-ecdhPop-sha256-hmac-sha256                |
   |       | OID:         1.3.6.1.5.5.7.6.26                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1A          |
   |       | Comments:    Proof-of-possession algorithm, indexed with  |



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   |       |              KDF and MAC, see RFC 6955. Requires          |
   |       |              recipient's public static Diffie-Hellman key |
   +-------+-----------------------------------------------------------+
   |    15 | Name:        PoP with SHA-384 and HMAC-SHA384             |
   |       | Identifiers: sa-ecdhPop-sha384-hmac-sha384                |
   |       | OID:         1.3.6.1.5.5.7.6.27                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1B          |
   |       | Comments:    Proof-of-possession algorithm, indexed with  |
   |       |              KDF and MAC, see RFC 6955. Requires          |
   |       |              recipient's public static Diffie-Hellman key |
   +-------+-----------------------------------------------------------+
   |    16 | Name:        PoP with SHA-512 and HMAC-SHA512             |
   |       | Identifiers: sa-ecdhPop-sha512-hmac-sha512                |
   |       | OID:         1.3.6.1.5.5.7.6.28                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1C          |
   |       | Comments:    Proof-of-possession algorithm, indexed with  |
   |       |              KDF and MAC, see RFC 6955. Requires          |
   |       |              recipient's public static Diffie-Hellman key |
   +-------+-----------------------------------------------------------+
   |    23 | Name:        RSASSA-PKCS1-v1_5 with SHA-256               |
   |       | Identifiers: sha256WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.11                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0B 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    24 | Name:        RSASSA-PKCS1-v1_5 with SHA-384               |
   |       | Identifiers: sha384WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.12                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0C 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    25 | Name:        RSASSA-PKCS1-v1_5 with SHA-512               |
   |       | Identifiers: sha512WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.13                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0D 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    26 | Name:        RSASSA-PSS with SHA-256                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-256, MGF-1 with SHA-256, saltLength = 32 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 01 |



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   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 01 |
   |       |              05 00 a2 03 02 01 20                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    27 | Name:        RSASSA-PSS with SHA-384                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-384, MGF-1 with SHA-384, saltLength = 48 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 02 |
   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 02 |
   |       |              05 00 A2 03 02 01 30                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    28 | Name:        RSASSA-PSS with SHA-512                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-512, MGF-1 with SHA-512, saltLength = 64 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 03 |
   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 03 |
   |       |              05 00 A2 03 02 01 40                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    29 | Name:        RSASSA-PSS with SHAKE128                     |
   |       | Identifiers: id-RSASSA-PSS-SHAKE128                       |
   |       | OID:         1.3.6.1.5.5.7.6.30                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1E          |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    30 | Name:        RSASSA-PSS with SHAKE256                     |
   |       | Identifiers: id-RSASSA-PSS-SHAKE256                       |
   |       | OID:         1.3.6.1.5.5.7.6.31                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1F          |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    45 | Name:        SM2 with SM3                                 |
   |       | Identifiers: sm2-with-sm3                                 |
   |       | OID:         1.2.156.10197.1.501                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 81 1C CF 55 01 83 75          |
   |       | Comments:    See Section 3.2.2.                           |
   +-------+-----------------------------------------------------------+



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                    Figure 18: C509 Signature Algorithms

9.14.  C509 Public Key Algorithms Registry

   IANA has created a new registry titled "C509 Public Key Algorithms"
   in the new registry group "CBOR Encoded X.509 (C509) Parameters".
   The fields of the registry are Value, Name, Identifiers, OID,
   Parameters, DER, Comments, and Reference, where Value is an integer,
   and the other columns are text strings.  The fields Name, OID,
   Parameters, and DER are mandatory.  If the public key can only be
   used with one signature algorithm and the OID of the public key
   algorithm is the same as the signature algorithm, then the value MUST
   be chosen equal to the value of signature algorithm, see
   Section 9.13.  For values in the interval [-24, 23] the registration
   procedure is "IETF Review with Expert Review".  For all other values
   the registration procedure is "Expert Review".  The initial contents
   of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | X.509 Public Key Algorithms                               |
   +=======+===========================================================+
   |     0 | Name:        RSA                                          |
   |       | Identifiers: rsaEncryption                                |
   |       | OID:         1.2.840.113549.1.1.1                         |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0d 06 09 2a 86 48 86 f7 0d 01 01 01 05 00 |
   |       | Comments:    Compressed subjectPublicKey                  |
   +-------+-----------------------------------------------------------+
   |     1 | Name:        EC Public Key (Weierstrass) with secp256r1   |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = secp256r1 (1.2.840.10045.3.1.7) |
   |       | DER:         30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 |
   |       |              48 CE 3D 03 01 07                            |
   |       | Comments:    Compressed subjectPublicKey                  |
   |       |              Also known as P-256, ansip256r1, prime256v1  |
   +-------+-----------------------------------------------------------+
   |     2 | Name:        EC Public Key (Weierstrass) with secp384r1   |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = secp384r1 (1.3.132.0.34)        |
   |       | DER:         30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 |
   |       |              04 00 22                                     |
   |       | Comments:    Compressed subjectPublicKey                  |
   |       |              Also known as P-384, ansip384r1              |
   +-------+-----------------------------------------------------------+
   |     3 | Name:        EC Public Key (Weierstrass) with secp521r1   |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |



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   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = secp521r1 (1.3.132.0.35)        |
   |       | DER:         30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 |
   |       |              04 00 23                                     |
   |       | Comments:    Compressed subjectPublicKey                  |
   |       |              Also known as P-521, ansip521r1              |
   +-------+-----------------------------------------------------------+
   |     8 | Name:        X25519 (Montgomery)                          |
   |       | Identifiers: id-X25519                                    |
   |       | OID:         1.3.101.110                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 6E                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9 | Name:        X448 (Montgomery)                            |
   |       | Identifiers: id-X448                                      |
   |       | OID:         1.3.101.111                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 6F                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    12 | Name:        Ed25519 (Twisted Edwards)                    |
   |       | Identifiers: id-Ed25519, id-EdDSA25519                    |
   |       | OID:         1.3.101.112                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 70                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:        Ed448 (Edwards)                              |
   |       | Identifiers: id-Ed448, id-EdDSA448                        |
   |       | OID:         1.3.101.113                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 71                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    24 | Name:        EC Public Key (Weierstrass) with             |
   |       |              brainpoolP256r1                              |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = brainpoolP256r1                 |
   |       |              (1.3.36.3.3.2.8.1.1.7)                       |
   |       | DER:         30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 |
   |       |              03 03 02 08 01 01 07                         |
   |       | Comments:    Compressed subjectPublicKey                  |
   +-------+-----------------------------------------------------------+
   |    25 | Name:        EC Public Key (Weierstrass) with             |
   |       |              brainpoolP384r1                              |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |



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   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = brainpoolP384r1                 |
   |       |              (1.3.36.3.3.2.8.1.1.11)                      |
   |       | DER:         30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 |
   |       |              03 03 02 08 01 01 0B                         |
   |       | Comments:    Compressed subjectPublicKey                  |
   +-------+-----------------------------------------------------------+
   |    26 | Name:        EC Public Key (Weierstrass) with             |
   |       |              brainpoolP512r1                              |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = brainpoolP512r1                 |
   |       |              (1.3.36.3.3.2.8.1.1.13)                      |
   |       | DER:         30 14 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 |
   |       |              03 03 02 08 01 01 0D                         |
   |       | Comments:    Compressed subjectPublicKey                  |
   +-------+-----------------------------------------------------------+
   |    27 | Name:        EC Public Key (Weierstrass) with             |
   |       |              FRP256v1                                     |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = FRP256v1                        |
   |       |              (1.2.250.1.223.101.256.1)                    |
   |       | DER:         30 15 06 07 2A 86 48 CE 3D 02 01 06 0A 2A 81 |
   |       |              7A 01 81 5F 65 82 00 01                      |
   |       | Comments:    Compressed subjectPublicKey                  |
   +-------+-----------------------------------------------------------+
   |    28 | Name:        EC Public Key (Weierstrass) with             |
   |       |              sm2p256v1                                    |
   |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
   |       | OID:         1.2.840.10045.2.1                            |
   |       | Parameters:  namedCurve = sm2p256v1                       |
   |       |              (1.2.156.10197.1.301)                        |
   |       | DER:         30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 81 |
   |       |              1C CF 55 01 82 2D                            |
   |       | Comments:    Compressed subjectPublicKey                  |
   +-------+-----------------------------------------------------------+

                   Figure 19: C509 Public Key Algorithms












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9.14.1.  Suitability of different public key algorithms for use within
         IoT scenarios

   The public key algorithms registry Section 9.14 specifies a number of
   algorithms, not all which are suitable for usage with constrained
   devices.  RSA requires large keys and large signature sizes compared
   to elliptic curve cryptography (ECC), which together with resource-
   efficient implementations of named elliptic curves (Montgomery,
   Edwards and Weierstrass curves) make them suitable candidates for IoT
   public key usage.  These curves are represented by ids 1–11 and 24–28
   in Section 9.14.

9.15.  COSE Header Parameters Registry

   IANA is requested to assign the entries in Table 1 to the "COSE
   Header Parameters" registry in the registry group "CBOR Object
   Signing and Encryption (COSE)" with this document as reference.

9.16.  Media Type Application Registry

   IANA is requested to assign the following entries in to the
   "application" registry in the registry group "Media Types" with this
   document as reference.

9.16.1.  Media Type application/cose-c509-cert

   When the application/cose-c509-cert media type is used, the data is a
   COSE_C509 structure.  If the parameter "usage" is set to "chain",
   this sequence indicates a certificate chain.

   Type name: application

   Subtype name: cose-c509-cert

   Required parameters: N/A

   Optional parameters: usage

   *  Can be absent to provide no further information about the intended
      meaning of the order in the CBOR sequence of certificates.

   *  Can be set to "chain" to indicate that the sequence of data items
      is to be interpreted as a certificate chain.

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].



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   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and use C509 as a certificate type.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD8, TBD6

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IETF

9.16.2.  Media Type application/cose-c509-pkcs10

   When the application/cose-c509-pkcs10 media type is used, the data is
   a C509CertificateRequest structure.

   Type name: application

   Subtype name: cose-c509-pkcs10

   Required parameters: N/A

   Optional parameters: N/A

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].




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   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and C509 Certificate Request.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD9

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IETF

9.16.3.  Media Type application/cose-c509-crtemplate

   When the application/cose-c509-crtemplate media type is used, the
   data is a C509CertificateRequestTemplate structure.

   Type name: application

   Subtype name: cose-c509-crtemplate

   Required parameters: N/A

   Optional parameters: N/A

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].




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   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and C509 Certificate Request.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD18

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IETF

9.16.4.  Media Type application/cose-c509-privkey

   When the application/cose-c509-privkey media type is used, the data
   is a C509PrivateKey structure.

   Type name: application

   Subtype name: cose-c509-privkey

   Required parameters: N/A

   Optional parameters: usage

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].




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   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and use C509 as a certificate type.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD12

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IETF

9.16.5.  Media Type application/cose-c509-pem

   When the application/cose-c509-pem media type is used, the data is a
   C509PEM structure.

   Type name: application

   Subtype name: cose-c509-pem

   Required parameters: N/A

   Optional parameters: usage

   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [[this document]].




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   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and use C509 as a certificate type.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): TBD13

   *  File extension(s): .c509

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IETF

9.16.6.  Media Type application/cose-certhash

   When the application/cose-certhash media type is used, the data is a
   COSE_CertHash structure, see [RFC9360].

   Type name: application

   Subtype name: cose-certhash

   Required parameters: N/A

   Optional parameters: usage

   *  Can be absent to provide no further information about what the
      hash value is calculated over.

   *  Can be set to "c509" to indicate that the hash value is calculated
      over a C509 certificate, see Section 3.4.



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   Encoding considerations: binary

   Security considerations: See the Security Considerations section of
   [RFC9360].

   Interoperability considerations: N/A

   Published specification: [[this document]]

   Applications that use this media type: Applications that employ COSE
   and use X.509 or C509 as certificate type.

   Fragment identifier considerations: N/A

   Additional information:

   *  Deprecated alias names for this type: N/A

   *  Magic number(s): N/A

   *  File extension(s): N/A

   *  Macintosh file type code(s): N/A

   Person & email address to contact for further information:
   iesg@ietf.org

   Intended usage: COMMON

   Restrictions on usage: N/A

   Author: COSE WG

   Change controller: IETF

9.17.  CoAP Content-Formats Registry

   IANA is requested to add entries for "application/cose-c509-cert",
   "application/cose-c509-pkcs10", "application/cose-c509-crtemplate",
   "application/cose-c509-privkey" and "application/cose-c509-pem" to
   the "CoAP Content-Formats" registry in the registry group
   "Constrained RESTful Environments (CoRE) Parameters".  A dedicated
   Content-Format ID is requested for the "application/cose-c509-cert"
   media type in the case when the parameter "usage" is set to "chain",
   see Section 9.16.1.






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   IANA is requested to add entries for "application/cose-certhash" to
   the "CoAP Content-Formats" registry in the registry group
   "Constrained RESTful Environments (CoRE) Parameters".  A dedicated
   Content-Format ID is requested in the case when the parameter "usage"
   is set to "c509", see Section 9.16.1.

   IANA is requested to add entries for "application/cbor" to the "CoAP
   Content-Formats" registry in the registry group "Constrained RESTful
   Environments (CoRE) Parameters", in the case when the encoding is a
   CBOR text string containing a URI, see [RFC3986].

+----------------------+---------+------------------+-------+--------------+
| Content              | Content | Media            | ID    | Reference    |
| Format               | Coding  | Type             |       |              |
+======================+=========+==================+=======+==============+
| application/         | -       | [[link to 9.15]] | TBD3  | [[this       |
| cose-c509-cert       |         |                  |       |   document]] |
+----------------------+---------+------------------+-------+--------------+
| application/         |         |                  |       | [[this       |
| cose-c509-cert;      | -       | [[link to 9.15]] | TBD15 |   document]] |
| usage = chain        |         |                  |       |              |
+----------------------+---------+------------------+-------+--------------+
| application/         | -       | [[link to 9.15]] | TBD4  | [[this       |
| cose-c509-pkcs10     |         |                  |       |   document]] |
+----------------------+---------+------------------+-------+--------------+
| application/         | -       | [[link to 9.15]] | TBD19 | [[this       |
| cose-c509-crtemplate |         |                  |       |   document]] |
+----------------------+---------+------------------+-------+--------------+
| application/         | -       | [[link to 9.15]] | TBD10 | [[this       |
| cose-c509-privkey    |         |                  |       |   document]] |
+----------------------+---------+------------------+-------+--------------+
| application/         | -       | [[link to 9.15]] | TBD11 | [[this       |
| cose-c509-pem        |         |                  |       |   document]] |
+----------------------+---------+------------------+-------+--------------+
| application/         | -       | [[link to 9.15]] | TBD16 | [[this       |
| cose-certhash        |         |                  |       |   document]] |
+----------------------+---------+------------------+-------+--------------+
| application/         |         |                  |       | [[this       |
| cose-certhash;       | -       | [[link to 9.15]] | TBD17 |   document]] |
| usage = c509         |         |                  |       |              |
+----------------------+---------+------------------+-------+--------------+

                  Figure 20: CoAP Content-Format IDs








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9.18.  TLS Certificate Types Registry

   This document registers the following entry in the "TLS Certificate
   Types" registry in the registry group "Transport Layer Security (TLS)
   Extensions".  The new certificate type can be used with additional
   TLS certificate compression [RFC8879].  For TLS 1.3, the C509
   certificate type is defined as a new case in the CertificateEntry
   struct specified in Section 4.4.2 of [RFC8446]:

   case C509:
     opaque c509_data<1..2^24-1>;

   where c509_data is the CBOR sequence ~C509Certificate (an unwrapped
   C509Certificate).  For TLS 1.2 the same construction is applied with
   a similar union type defined for the Certificate struct in
   Section 7.4.2 of [RFC5246].  Note that, similar to COSE_C509, the TLS
   handshake contains the length of each certificate.  The TLS
   extensions client_certificate_type and server_certificate_type
   [RFC7250] are used to negotiate the use of C509.

   +-------+------------------+-------------+--------------------------+
   | Value | Name             | Recommended | Comment                  |
   +=======+==================+=============+==========================+
   |  TBD5 | C509 Certificate |           N |                          |
   +-------+------------------+-------------+--------------------------+

9.19.  TLSA Selectors Registry

   This document registers the following entry in the "TLSA Selectors"
   registry in the registry group "DNS-Based Authentication of Named
   Entities (DANE) Parameters".  The C509 certificate data,
   C509CertData, is defined in Section 3.4.

   +-------+---------+------------------------+-------------------+
   | Value | Acronym |   Short Description    |     Reference     |
   +=======+=========+========================+===================+
   |  TBD7 |    C509 | C509 certificate data  | [[this document]] |
   +-------+---------+------------------------+-------------------+

   The TLSA selectors registry defined in [RFC6698] originally only
   applied to PKIX [RFC5280] certificates in DER encoding.  This
   specification updates [RFC6698] to accept the use of C509
   certificates.








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9.20.  EDHOC Authentication Credential Types Registry

   This document registers the following entry in the "EDHOC
   Authentication Credential Types" registry in the registry group
   "Ephemeral Diffie-Hellman Over COSE (EDHOC)".  This is useful to
   identify C509 certificates as a supported authentication credential
   type to use with EDHOC [RFC9528], for example, during discovery of
   EDHOC resources, see [RFC9668].

   +-------+----------------------+-------------------+
   | Value | Description          |     Reference     |
   +=======+======================+===================+
   |   3   | C509 certificate     | [[this document]] |
   +-------+----------------------+-------------------+

10.  References

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC2985]  Nystrom, M. and B. Kaliski, "PKCS #9: Selected Object
              Classes and Attribute Types Version 2.0", RFC 2985,
              DOI 10.17487/RFC2985, November 2000,
              <https://www.rfc-editor.org/rfc/rfc2985>.

   [RFC2986]  Nystrom, M. and B. Kaliski, "PKCS #10: Certification
              Request Syntax Specification Version 1.7", RFC 2986,
              DOI 10.17487/RFC2986, November 2000,
              <https://www.rfc-editor.org/rfc/rfc2986>.

   [RFC3779]  Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP
              Addresses and AS Identifiers", RFC 3779,
              DOI 10.17487/RFC3779, June 2004,
              <https://www.rfc-editor.org/rfc/rfc3779>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/rfc/rfc3986>.

   [RFC4108]  Housley, R., "Using Cryptographic Message Syntax (CMS) to
              Protect Firmware Packages", RFC 4108,
              DOI 10.17487/RFC4108, August 2005,
              <https://www.rfc-editor.org/rfc/rfc4108>.



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   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/rfc/rfc5246>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/rfc/rfc5280>.

   [RFC5958]  Turner, S., "Asymmetric Key Packages", RFC 5958,
              DOI 10.17487/RFC5958, August 2010,
              <https://www.rfc-editor.org/rfc/rfc5958>.

   [RFC6066]  Eastlake 3rd, D., "Transport Layer Security (TLS)
              Extensions: Extension Definitions", RFC 6066,
              DOI 10.17487/RFC6066, January 2011,
              <https://www.rfc-editor.org/rfc/rfc6066>.

   [RFC6698]  Hoffman, P. and J. Schlyter, "The DNS-Based Authentication
              of Named Entities (DANE) Transport Layer Security (TLS)
              Protocol: TLSA", RFC 6698, DOI 10.17487/RFC6698, August
              2012, <https://www.rfc-editor.org/rfc/rfc6698>.

   [RFC6962]  Laurie, B., Langley, A., and E. Kasper, "Certificate
              Transparency", RFC 6962, DOI 10.17487/RFC6962, June 2013,
              <https://www.rfc-editor.org/rfc/rfc6962>.

   [RFC7030]  Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
              "Enrollment over Secure Transport", RFC 7030,
              DOI 10.17487/RFC7030, October 2013,
              <https://www.rfc-editor.org/rfc/rfc7030>.

   [RFC7120]  Cotton, M., "Early IANA Allocation of Standards Track Code
              Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January
              2014, <https://www.rfc-editor.org/rfc/rfc7120>.

   [RFC7250]  Wouters, P., Ed., Tschofenig, H., Ed., Gilmore, J.,
              Weiler, S., and T. Kivinen, "Using Raw Public Keys in
              Transport Layer Security (TLS) and Datagram Transport
              Layer Security (DTLS)", RFC 7250, DOI 10.17487/RFC7250,
              June 2014, <https://www.rfc-editor.org/rfc/rfc7250>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/rfc/rfc8126>.



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   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8295]  Turner, S., "EST (Enrollment over Secure Transport)
              Extensions", RFC 8295, DOI 10.17487/RFC8295, January 2018,
              <https://www.rfc-editor.org/rfc/rfc8295>.

   [RFC8360]  Huston, G., Michaelson, G., Martinez, C., Bruijnzeels, T.,
              Newton, A., and D. Shaw, "Resource Public Key
              Infrastructure (RPKI) Validation Reconsidered", RFC 8360,
              DOI 10.17487/RFC8360, April 2018,
              <https://www.rfc-editor.org/rfc/rfc8360>.

   [RFC8398]  Melnikov, A., Ed. and W. Chuang, Ed., "Internationalized
              Email Addresses in X.509 Certificates", RFC 8398,
              DOI 10.17487/RFC8398, May 2018,
              <https://www.rfc-editor.org/rfc/rfc8398>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.

   [RFC8742]  Bormann, C., "Concise Binary Object Representation (CBOR)
              Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
              <https://www.rfc-editor.org/rfc/rfc8742>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/rfc/rfc8949>.

   [RFC9052]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Structures and Process", STD 96, RFC 9052,
              DOI 10.17487/RFC9052, August 2022,
              <https://www.rfc-editor.org/rfc/rfc9052>.

   [RFC9090]  Bormann, C., "Concise Binary Object Representation (CBOR)
              Tags for Object Identifiers", RFC 9090,
              DOI 10.17487/RFC9090, July 2021,
              <https://www.rfc-editor.org/rfc/rfc9090>.

   [RFC9277]  Richardson, M. and C. Bormann, "On Stable Storage for
              Items in Concise Binary Object Representation (CBOR)",
              RFC 9277, DOI 10.17487/RFC9277, August 2022,
              <https://www.rfc-editor.org/rfc/rfc9277>.



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   [RFC9360]  Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Header Parameters for Carrying and Referencing X.509
              Certificates", RFC 9360, DOI 10.17487/RFC9360, February
              2023, <https://www.rfc-editor.org/rfc/rfc9360>.

   [RFC9542]  Eastlake 3rd, D., Abley, J., and Y. Li, "IANA
              Considerations and IETF Protocol and Documentation Usage
              for IEEE 802 Parameters", BCP 141, RFC 9542,
              DOI 10.17487/RFC9542, April 2024,
              <https://www.rfc-editor.org/rfc/rfc9542>.

   [RFC9668]  Palombini, F., Tiloca, M., Höglund, R., Hristozov, S., and
              G. Selander, "Using Ephemeral Diffie-Hellman Over COSE
              (EDHOC) with the Constrained Application Protocol (CoAP)
              and Object Security for Constrained RESTful Environments
              (OSCORE)", RFC 9668, DOI 10.17487/RFC9668, November 2024,
              <https://www.rfc-editor.org/rfc/rfc9668>.

   [RFC9883]  Housley, R., "An Attribute for Statement of Possession of
              a Private Key", RFC 9883, DOI 10.17487/RFC9883, October
              2025, <https://www.rfc-editor.org/rfc/rfc9883>.

   [SECG]     "Elliptic Curve Cryptography, Standards for Efficient
              Cryptography Group, ver. 2", 2009,
              <https://secg.org/sec1-v2.pdf>.

   [X.501]    "Information Technology - Open Systems Interconnection -
              The Directory: Models, ITU-T X.501", December 2019,
              <https://www.itu.int/rec/T-REC-X.501/en>.

   [X.690]    "ASN.1 encoding rules. Specification of Basic Encoding
              Rules (BER), Canonical Encoding Rules (CER) and
              Distinguished Encoding Rules (DER)", n.d.,
              <https://www.itu.int/rec/T-REC-X.690>.

10.2.  Informative References

   [CAB-Code] CA/Browser Forum, "CA/Browser Forum, "Baseline
              Requirements for the Issuance and Management of Publicly-
              Trusted Code Signing Certificates Version 3.8.0"", August
              2024, <https://cabforum.org/baseline-requirements-code-
              signing/>.

   [CAB-TLS]  CA/Browser Forum, "CA/Browser Forum, "Baseline
              Requirements for the Issuance and Management of Publicly-
              Trusted Certificates Version 2.1.4"", March 2025,
              <https://cabforum.org/baseline-requirements-documents/>.




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   [CborMe]   Bormann, C., "CBOR Playground", May 2018,
              <https://cbor.me/>.

   [GSMA-eUICC]
              GSMA, "GSMA eUICC PKI Certificate Policy Version 2.2",
              January 2025, <https://www.gsma.com/solutions-and-
              impact/technologies/esim/wp-content/uploads/2025/01/
              SGP.14-v2.2.pdf>.

   [I-D.bormann-cbor-notable-tags]
              Bormann, C., "Notable CBOR Tags", Work in Progress,
              Internet-Draft, draft-bormann-cbor-notable-tags-16, 25
              February 2026, <https://datatracker.ietf.org/doc/html/
              draft-bormann-cbor-notable-tags-16>.

   [I-D.ietf-lamps-macaddress-on]
              Housley, R., Bonnell, C., Mandel, J., Okubo, T., and M.
              StJohns, "Media Access Control (MAC) Addresses in X.509
              Certificates", Work in Progress, Internet-Draft, draft-
              ietf-lamps-macaddress-on-06, 18 February 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-lamps-
              macaddress-on-06>.

   [I-D.ietf-lamps-rfc7030-csrattrs]
              Richardson, M., Friel, O., von Oheimb, D., and D. Harkins,
              "Clarification and enhancement of RFC7030 CSR Attributes
              definition", Work in Progress, Internet-Draft, draft-ietf-
              lamps-rfc7030-csrattrs-23, 28 June 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-lamps-
              rfc7030-csrattrs-23>.

   [I-D.ietf-tls-ctls]
              Rescorla, E., Barnes, R., Tschofenig, H., and B. M.
              Schwartz, "Compact TLS 1.3", Work in Progress, Internet-
              Draft, draft-ietf-tls-ctls-10, 17 April 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-tls-
              ctls-10>.

   [I-D.ietf-uta-tls13-iot-profile]
              Tschofenig, H., Fossati, T., Richardson, M., and D.
              Migault, "TLS/DTLS 1.3 Profiles for the Internet of
              Things", Work in Progress, Internet-Draft, draft-ietf-uta-
              tls13-iot-profile-19, 20 February 2026,
              <https://datatracker.ietf.org/doc/html/draft-ietf-uta-
              tls13-iot-profile-19>.






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   [IEEE-802.1AR]
              Institute of Electrical and Electronics Engineers, "IEEE
              Standard for Local and metropolitan area networks–Secure
              Device Identity", IEEE Standard 802.1AR-2018 , August
              2018,
              <https://standards.ieee.org/standard/802_1AR-2018.html>.

   [RFC6487]  Huston, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates", RFC 6487,
              DOI 10.17487/RFC6487, February 2012,
              <https://www.rfc-editor.org/rfc/rfc6487>.

   [RFC6955]  Schaad, J. and H. Prafullchandra, "Diffie-Hellman Proof-
              of-Possession Algorithms", RFC 6955, DOI 10.17487/RFC6955,
              May 2013, <https://www.rfc-editor.org/rfc/rfc6955>.

   [RFC7228]  Bormann, C., Ersue, M., and A. Keranen, "Terminology for
              Constrained-Node Networks", RFC 7228,
              DOI 10.17487/RFC7228, May 2014,
              <https://www.rfc-editor.org/rfc/rfc7228>.

   [RFC7468]  Josefsson, S. and S. Leonard, "Textual Encodings of PKIX,
              PKCS, and CMS Structures", RFC 7468, DOI 10.17487/RFC7468,
              April 2015, <https://www.rfc-editor.org/rfc/rfc7468>.

   [RFC7925]  Tschofenig, H., Ed. and T. Fossati, "Transport Layer
              Security (TLS) / Datagram Transport Layer Security (DTLS)
              Profiles for the Internet of Things", RFC 7925,
              DOI 10.17487/RFC7925, July 2016,
              <https://www.rfc-editor.org/rfc/rfc7925>.

   [RFC7932]  Alakuijala, J. and Z. Szabadka, "Brotli Compressed Data
              Format", RFC 7932, DOI 10.17487/RFC7932, July 2016,
              <https://www.rfc-editor.org/rfc/rfc7932>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/rfc/rfc8446>.

   [RFC8603]  Jenkins, M. and L. Zieglar, "Commercial National Security
              Algorithm (CNSA) Suite Certificate and Certificate
              Revocation List (CRL) Profile", RFC 8603,
              DOI 10.17487/RFC8603, May 2019,
              <https://www.rfc-editor.org/rfc/rfc8603>.

   [RFC8879]  Ghedini, A. and V. Vasiliev, "TLS Certificate
              Compression", RFC 8879, DOI 10.17487/RFC8879, December
              2020, <https://www.rfc-editor.org/rfc/rfc8879>.



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   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
              Multiplexed and Secure Transport", RFC 9000,
              DOI 10.17487/RFC9000, May 2021,
              <https://www.rfc-editor.org/rfc/rfc9000>.

   [RFC9147]  Rescorla, E., Tschofenig, H., and N. Modadugu, "The
              Datagram Transport Layer Security (DTLS) Protocol Version
              1.3", RFC 9147, DOI 10.17487/RFC9147, April 2022,
              <https://www.rfc-editor.org/rfc/rfc9147>.

   [RFC9148]  van der Stok, P., Kampanakis, P., Richardson, M., and S.
              Raza, "EST-coaps: Enrollment over Secure Transport with
              the Secure Constrained Application Protocol", RFC 9148,
              DOI 10.17487/RFC9148, April 2022,
              <https://www.rfc-editor.org/rfc/rfc9148>.

   [RFC9190]  Preuß Mattsson, J. and M. Sethi, "EAP-TLS 1.3: Using the
              Extensible Authentication Protocol with TLS 1.3",
              RFC 9190, DOI 10.17487/RFC9190, February 2022,
              <https://www.rfc-editor.org/rfc/rfc9190>.

   [RFC9191]  Sethi, M., Preuß Mattsson, J., and S. Turner, "Handling
              Large Certificates and Long Certificate Chains in TLS-
              Based EAP Methods", RFC 9191, DOI 10.17487/RFC9191,
              February 2022, <https://www.rfc-editor.org/rfc/rfc9191>.

   [RFC9528]  Selander, G., Preuß Mattsson, J., and F. Palombini,
              "Ephemeral Diffie-Hellman Over COSE (EDHOC)", RFC 9528,
              DOI 10.17487/RFC9528, March 2024,
              <https://www.rfc-editor.org/rfc/rfc9528>.

   [SP-800-56A]
              Barker, E., Chen, L., Roginsky, A., Vassilev, A., and R.
              Davis, "Recommendation for Pair-Wise Key-Establishment
              Schemes Using Discrete Logarithm Cryptography",
              NIST Special Publication 800-56A Revision 3, April 2018,
              <https://doi.org/10.6028/NIST.SP.800-56Ar3>.

   [X.509-IoT]
              Forsby, F., Furuhed, M., Papadimitratos, P., and S. Raza,
              "Lightweight X.509 Digital Certificates for the Internet
              of Things.", Springer, Cham. Lecture Notes of the
              Institute for Computer Sciences, Social Informatics and
              Telecommunications Engineering, vol 242., July 2018,
              <https://doi.org/10.1007/978-3-319-93797-7_14>.

Appendix A.  C509 Certificate Examples




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A.1.  Example: RFC 7925 profiled X.509 Certificate

   Example of [RFC7925] profiled X.509 certificate parsed with OpenSSL.

   Certificate:
       Data:
           Version: 3 (0x2)
           Serial Number: 128269 (0x1f50d)
           Signature Algorithm: ecdsa-with-SHA256
           Issuer: CN=RFC test CA
           Validity
               Not Before: Jan  1 00:00:00 2023 GMT
               Not After : Jan  1 00:00:00 2026 GMT
           Subject: CN=01-23-45-FF-FE-67-89-AB
           Subject Public Key Info:
               Public Key Algorithm: id-ecPublicKey
                   Public-Key: (256 bit)
                   pub:
                       04:b1:21:6a:b9:6e:5b:3b:33:40:f5:bd:f0:2e:69:
                       3f:16:21:3a:04:52:5e:d4:44:50:b1:01:9c:2d:fd:
                       38:38:ab:ac:4e:14:d8:6c:09:83:ed:5e:9e:ef:24:
                       48:c6:86:1c:c4:06:54:71:77:e6:02:60:30:d0:51:
                       f7:79:2a:c2:06
                   ASN1 OID: prime256v1
                   NIST CURVE: P-256
           X509v3 extensions:
               X509v3 Key Usage:
                   Digital Signature
       Signature Algorithm: ecdsa-with-SHA256
           30:46:02:21:00:d4:32:0b:1d:68:49:e3:09:21:9d:30:03:7e:
           13:81:66:f2:50:82:47:dd:da:e7:6c:ce:ea:55:05:3c:10:8e:
           90:02:21:00:d5:51:f6:d6:01:06:f1:ab:b4:84:cf:be:62:56:
           c1:78:e4:ac:33:14:ea:19:19:1e:8b:60:7d:a5:ae:3b:da:16

   The DER encoding of the above certificate is 316 bytes.
















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   30 82 01 38 30 81 de a0 03 02 01 02 02 03 01 f5 0d 30 0a 06 08 2a 86
   48 ce 3d 04 03 02 30 16 31 14 30 12 06 03 55 04 03 0c 0b 52 46 43 20
   74 65 73 74 20 43 41 30 1e 17 0d 32 33 30 31 30 31 30 30 30 30 30 30
   5a 17 0d 32 36 30 31 30 31 30 30 30 30 30 30 5a 30 22 31 20 30 1e 06
   03 55 04 03 0c 17 30 31 2d 32 33 2d 34 35 2d 46 46 2d 46 45 2d 36 37
   2d 38 39 2d 41 42 30 59 30 13 06 07 2a 86 48 ce 3d 02 01 06 08 2a 86
   48 ce 3d 03 01 07 03 42 00 04 b1 21 6a b9 6e 5b 3b 33 40 f5 bd f0 2e
   69 3f 16 21 3a 04 52 5e d4 44 50 b1 01 9c 2d fd 38 38 ab ac 4e 14 d8
   6c 09 83 ed 5e 9e ef 24 48 c6 86 1c c4 06 54 71 77 e6 02 60 30 d0 51
   f7 79 2a c2 06 a3 0f 30 0d 30 0b 06 03 55 1d 0f 04 04 03 02 07 80 30
   0a 06 08 2a 86 48 ce 3d 04 03 02 03 49 00 30 46 02 21 00 d4 32 0b 1d
   68 49 e3 09 21 9d 30 03 7e 13 81 66 f2 50 82 47 dd da e7 6c ce ea 55
   05 3c 10 8e 90 02 21 00 d5 51 f6 d6 01 06 f1 ab b4 84 cf be 62 56 c1
   78 e4 ac 33 14 ea 19 19 1e 8b 60 7d a5 ae 3b da 16

A.1.1.  Example: C509 Certificate Encoding

   This section shows the C509 encoding of the X.509 certificate in the
   previous section.  The point compressed public key is represented as
   described in Section 3.2.1.

   Figure 21 shows the diagnostic notation of the unwrapped CBOR
   sequence, ~C509Certificate, see Section 3.1.

   /This defines a CBOR Sequence (RFC 8742):/

     3,                   / version and certificate type /
     h'01f50d',           / serialNumber /
     0,                   / signatureAlgorithm /
     "RFC test CA",       / issuer /
     1672531200,          / notBefore /
     1767225600,          / notAfter /
     48(h'0123456789AB'), / subject, EUI-64 /
     1,                   / subjectPublicKeyAlgorithm /
     h'FEB1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
       B1019C2DFD3838AB',
     1,                   / single extension:
                            non-critical keyUsage
                            digitalSignature /
     h'D4320B1D6849E309219D30037E138166F2508247DDDAE76CCE
       EA55053C108E90D551F6D60106F1ABB484CFBE6256C178E4AC
       3314EA19191E8B607DA5AE3BDA16'

          Figure 21: CBOR diagnostic notation of ~C509Certificate

   Figure 22 shows the plain hex format of the unwrapped CBOR sequence,
   the size is 140 bytes.




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   03
   43 01 F5 0D
   00
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 63 B0 CD 00
   1A 69 55 B9 00
   D8 30 46 01 23 45 67 89 AB
   01
   58 21 FE B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   58 40 D4 32 0B 1D 68 49 E3 09 21 9D 30 03 7E 13 81 66 F2 50 82 47 DD
   DA E7 6C CE EA 55 05 3C 10 8E 90 D5 51 F6 D6 01 06 F1 AB B4 84 CF BE
   62 56 C1 78 E4 AC 33 14 EA 19 19 1E 8B 60 7D A5 AE 3B DA 16

           Figure 22: CBOR plain hex format of ~C509Certificate.

A.1.2.  Example: Natively Signed C509 Certificate

   This section shows the natively signed C509 certificate corresponding
   to that of the previous section, which is identical except for
   c509CertificateType, encoding of point compression (see
   Section 3.2.1), and signatureValue.

   Figure 23 shows the diagnostic notation of the natively signed
   unwrapped CBOR sequence, ~C509Certificate.

   /This defines a CBOR Sequence (RFC 8742):/

     2,
     h'01f50d',
     0,
     "RFC test CA",
     1672531200,
     1767225600,
     48(h'0123456789AB'),
     1,
     h'02B1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
       B1019C2DFD3838AB',
     1,
     h'EB0D472731F689BC00F5880B12C68B3F9FD38B23FADFCA2095
       0F3F241B60A202579CAC28CD3B7494D5FA5D8BBAB4600357E5
       50AB9FA9A65D9BA2B3B82E668CC6'

          Figure 23: CBOR diagnostic notation of ~C509Certificate

   Figure 24 shows the plain hex format of the natively signed unwrapped
   CBOR sequence, the size is 140 bytes.



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   02
   43 01 F5 0D
   00
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 63 B0 CD 00
   1A 69 55 B9 00
   D8 30 46 01 23 45 67 89 AB
   01
   58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   58 40 EB 0D 47 27 31 F6 89 BC 00 F5 88 0B 12 C6 8B 3F 9F D3 8B 23 FA
   DF CA 20 95 0F 3F 24 1B 60 A2 02 57 9C AC 28 CD 3B 74 94 D5 FA 5D 8B
   BA B4 60 03 57 E5 50 AB 9F A9 A6 5D 9B A2 B3 B8 2E 66 8C C6

           Figure 24: CBOR plain hex format of ~C509Certificate.

A.1.3.  C509 for Diffie-Hellman keys

   The two previous examples illustrate keyUsage digitalSignature.  A
   C509 certificate for a public Diffie-Hellman key would instead have
   key usage keyAgreement encoded according to Section 3.3 (in this case
   of single extension encoded as integer 16 instead of 1 for digital
   signature) but otherwise identical in format.  Note that
   Section 5.6.3.2 of [SP-800-56A] allows a key agreement key pair to be
   used to sign a certificate request.

A.1.4.  Example: Additional Keys for the Example Certificates

   Below are the issuer key pair and the subject private key belonging
   to the above example certificates.  The private keys are encoded as
   in COSE [RFC9052].  These issuer key pair can be used to sign or
   verify the example certificates and the subject private key allows
   the example certificates to be used in test vectors for other
   protocols like EDHOC.

   issuerPublicKeyAlgorithm :
   1 (EC Public Key (Weierstrass) with secp256r1)

   issuerPublicKey :
   h'02AE4CDB01F614DEFC7121285FDC7F5C6D1D42C95647F061BA0080DF678867845E'

   issuerPrivateKey :
   h'DC66B3415456D649429B53223DF7532B942D6B0E0842C30BCA4C0ACF91547BB2'

   subjectPrivateKey :
   h'D718111F3F9BD91B92FF6877F386BDBFCEA7154268FD7F2FB56EE17D99EA16D4'




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A.1.5.  Examples: C509Certificate and C509CertData

   This section examplifies other CBOR objects defined in this
   specification, based on the natively signed C509 certificate in
   Appendix A.1.2.

   Figure 25 shows the encoding of the corresponding C509Certificate,
   i.e., the CBOR array wrapping of the CBOR sequence ~C509Certificate,
   see Section 3.1.

   8B
   02
   43 01 F5 0D
   00
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 63 B0 CD 00
   1A 69 55 B9 00
   D8 30 46 01 23 45 67 89 AB
   01
   58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   58 40 EB 0D 47 27 31 F6 89 BC 00 F5 88 0B 12 C6 8B 3F 9F D3 8B 23 FA
   DF CA 20 95 0F 3F 24 1B 60 A2 02 57 9C AC 28 CD 3B 74 94 D5 FA 5D 8B
   BA B4 60 03 57 E5 50 AB 9F A9 A6 5D 9B A2 B3 B8 2E 66 8C C6

           Figure 25: C509Certificate: The CBOR array wrapping of
                              ~C509Certificate

   Note that C509Certificate is identical to ~C509Certificate in
   Appendix A.1.2 except for the prefix 8B (which indicates that it is a
   CBOR array with 11 elements).

   Figure 26 shows the encoding of the corresponding C509CertData, i.e.,
   the CBOR byte string wrapping of the CBOR sequence ~C509Certificate,
   see Section 3.4.















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   58 8C
   02
   43 01 F5 0D
   00
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 63 B0 CD 00
   1A 69 55 B9 00
   D8 30 46 01 23 45 67 89 AB
   01
   58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   58 40 EB 0D 47 27 31 F6 89 BC 00 F5 88 0B 12 C6 8B 3F 9F D3 8B 23 FA
   DF CA 20 95 0F 3F 24 1B 60 A2 02 57 9C AC 28 CD 3B 74 94 D5 FA 5D 8B
   BA B4 60 03 57 E5 50 AB 9F A9 A6 5D 9B A2 B3 B8 2E 66 8C C6

           Figure 26: C509CertData: CBOR byte string wrapping of
                             ~C509Certificate.

   Note that C509CertData is identical to ~C509Certificate in
   Appendix A.1.2 except for the prefix 58 8C (which indicates that it
   is a CBOR byte string of 140 bytes).

A.2.  Example: IEEE 802.1AR profiled X.509 Certificate

   An example of an IEEE 802.1AR profiled X.509 certificate (Secure
   Device Identifier, DevID) is provided in Appendix C.2 of [RFC9148].
   The certificate is shown below including details of the
   hardwareModuleName type of otherName in subjectAltName, see
   Section 3.3.





















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Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 9112578475118446130 (0x7e7661d7b54e4632)
        Signature Algorithm: ecdsa-with-SHA256
        Issuer: C=US, ST=CA, O=Example Inc, OU=certification, CN=802.1AR CA
        Validity
            Not Before: Jan 31 11:29:16 2019 GMT
            Not After : Dec 31 23:59:59 9999 GMT
        Subject: C=US, ST=CA, L=LA, O=example Inc, OU=IoT/serialNumber=Wt1234
        Subject Public Key Info:
            Public Key Algorithm: id-ecPublicKey
                Public-Key: (256 bit)
                pub:
                    04:c8:b4:21:f1:1c:25:e4:7e:3a:c5:71:23:bf:2d:
                    9f:dc:49:4f:02:8b:c3:51:cc:80:c0:3f:15:0b:f5:
                    0c:ff:95:8d:75:41:9d:81:a6:a2:45:df:fa:e7:90:
                    be:95:cf:75:f6:02:f9:15:26:18:f8:16:a2:b2:3b:
                    56:38:e5:9f:d9
                ASN1 OID: prime256v1
                NIST CURVE: P-256
        X509v3 extensions:
            X509v3 Basic Constraints:
                CA:FALSE
            X509v3 Subject Key Identifier:
                96:60:0D:87:16:BF:7F:D0:E7:52:D0:AC:76:07:77:AD:66:5D:02:A0
            X509v3 Authority Key Identifier:
                68:D1:65:51:F9:51:BF:C8:2A:43:1D:0D:9F:08:BC:2D:20:5B:11:60
            X509v3 Key Usage: critical
                Digital Signature, Key Encipherment
            X509v3 Subject Alternative Name:
                otherName:
                    type-id: 1.3.6.1.5.5.7.8.4 (id-on-hardwareModuleName)
                    value:
                        hwType: 1.3.6.1.4.1.6715.10.1
                        hwSerialNum: 01:02:03:04
    Signature Algorithm: ecdsa-with-SHA256
    Signature Value:
        30:46:02:21:00:c0:d8:19:96:d2:50:7d:69:3f:3c:48:ea:a5:
        ee:94:91:bd:a6:db:21:40:99:d9:81:17:c6:3b:36:13:74:cd:
        86:02:21:00:a7:74:98:9f:4c:32:1a:5c:f2:5d:83:2a:4d:33:
        6a:08:ad:67:df:20:f1:50:64:21:18:8a:0a:de:6d:34:92:36

   The DER encoding of the certificate is 577 bytes:







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   30 82 02 3D 30 82 01 E2 A0 03 02 01 02 02 08 7E 76 61 D7 B5 4E 46 32
   30 0A 06 08 2A 86 48 CE 3D 04 03 02 30 5D 31 0B 30 09 06 03 55 04 06
   13 02 55 53 31 0B 30 09 06 03 55 04 08 0C 02 43 41 31 14 30 12 06 03
   55 04 0A 0C 0B 45 78 61 6D 70 6C 65 20 49 6E 63 31 16 30 14 06 03 55
   04 0B 0C 0D 63 65 72 74 69 66 69 63 61 74 69 6F 6E 31 13 30 11 06 03
   55 04 03 0C 0A 38 30 32 2E 31 41 52 20 43 41 30 20 17 0D 31 39 30 31
   33 31 31 31 32 39 31 36 5A 18 0F 39 39 39 39 31 32 33 31 32 33 35 39
   35 39 5A 30 5C 31 0B 30 09 06 03 55 04 06 13 02 55 53 31 0B 30 09 06
   03 55 04 08 0C 02 43 41 31 0B 30 09 06 03 55 04 07 0C 02 4C 41 31 14
   30 12 06 03 55 04 0A 0C 0B 65 78 61 6D 70 6C 65 20 49 6E 63 31 0C 30
   0A 06 03 55 04 0B 0C 03 49 6F 54 31 0F 30 0D 06 03 55 04 05 13 06 57
   74 31 32 33 34 30 59 30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 48
   CE 3D 03 01 07 03 42 00 04 C8 B4 21 F1 1C 25 E4 7E 3A C5 71 23 BF 2D
   9F DC 49 4F 02 8B C3 51 CC 80 C0 3F 15 0B F5 0C FF 95 8D 75 41 9D 81
   A6 A2 45 DF FA E7 90 BE 95 CF 75 F6 02 F9 15 26 18 F8 16 A2 B2 3B 56
   38 E5 9F D9 A3 81 8A 30 81 87 30 09 06 03 55 1D 13 04 02 30 00 30 1D
   06 03 55 1D 0E 04 16 04 14 96 60 0D 87 16 BF 7F D0 E7 52 D0 AC 76 07
   77 AD 66 5D 02 A0 30 1F 06 03 55 1D 23 04 18 30 16 80 14 68 D1 65 51
   F9 51 BF C8 2A 43 1D 0D 9F 08 BC 2D 20 5B 11 60 30 0E 06 03 55 1D 0F
   01 01 FF 04 04 03 02 05 A0 30 2A 06 03 55 1D 11 04 23 30 21 A0 1F 06
   08 2B 06 01 05 05 07 08 04 A0 13 30 11 06 09 2B 06 01 04 01 B4 3B 0A
   01 04 04 01 02 03 04 30 0A 06 08 2A 86 48 CE 3D 04 03 02 03 49 00 30
   46 02 21 00 C0 D8 19 96 D2 50 7D 69 3F 3C 48 EA A5 EE 94 91 BD A6 DB
   21 40 99 D9 81 17 C6 3B 36 13 74 CD 86 02 21 00 A7 74 98 9F 4C 32 1A
   5C F2 5D 83 2A 4D 33 6A 08 AD 67 DF 20 F1 50 64 21 18 8A 0A DE 6D 34
   92 36

A.2.1.  Example: C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the same X.509 certificate is
   shown below in CBOR diagnostic format.




















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 /This defines a CBOR Sequence (RFC 8742):/

  3,
  h'7E7661D7B54E4632',
  0,
  [
   -4, "US",
    6, "CA",
    8, "Example Inc",
    9, "certification",
    1, "802.1AR CA"
  ],
  1548934156,
  null,
  [
   -4, "US",
    6, "CA",
    5, "LA",
    8, "example Inc",
    9, "IoT",
   -3, "Wt1234"
  ],
  1,
  h'FDC8B421F11C25E47E3AC57123BF2D9FDC494F028BC351CC80C03F150BF50CFF95',
  [
    4, -2,
    1, h'96600D8716BF7FD0E752D0AC760777AD665D02A0',
    7, h'68D16551F951BFC82A431D0D9F08BC2D205B1160',
   -2, 5,
   3, [-1, [h'2B06010401B43B0A01', h'01020304']]
      / subjectAltName with hardwareModuleName /
  ],
  h'C0D81996D2507D693F3C48EAA5EE9491BDA6DB214099D98117C63B361374CD86A7
    74989F4C321A5CF25D832A4D336A08AD67DF20F1506421188A0ADE6D349236'

   The size of the CBOR encoding (CBOR sequence) is 275 bytes:















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   03 48 7E 76 61 D7 B5 4E 46 32 00 8A 23 62 55 53 06 62 43 41 08 6B 45
   78 61 6D 70 6C 65 20 49 6E 63 09 6D 63 65 72 74 69 66 69 63 61 74 69
   6F 6E 01 6A 38 30 32 2E 31 41 52 20 43 41 1A 5C 52 DC 0C F6 8C 23 62
   55 53 06 62 43 41 05 62 4C 41 08 6B 65 78 61 6D 70 6C 65 20 49 6E 63
   09 63 49 6F 54 22 66 57 74 31 32 33 34 01 58 21 FD C8 B4 21 F1 1C 25
   E4 7E 3A C5 71 23 BF 2D 9F DC 49 4F 02 8B C3 51 CC 80 C0 3F 15 0B F5
   0C FF 95 8A 04 21 01 54 96 60 0D 87 16 BF 7F D0 E7 52 D0 AC 76 07 77
   AD 66 5D 02 A0 07 54 68 D1 65 51 F9 51 BF C8 2A 43 1D 0D 9F 08 BC 2D
   20 5B 11 60 21 05 03 82 20 82 49 2B 06 01 04 01 B4 3B 0A 01 44 01 02
   03 04 58 40 C0 D8 19 96 D2 50 7D 69 3F 3C 48 EA A5 EE 94 91 BD A6 DB
   21 40 99 D9 81 17 C6 3B 36 13 74 CD 86 A7 74 98 9F 4C 32 1A 5C F2 5D
   83 2A 4D 33 6A 08 AD 67 DF 20 F1 50 64 21 18 8A 0A DE 6D 34 92 36

A.3.  Example: CAB Baseline ECDSA HTTPS X.509 Certificate

   The www.ietf.org HTTPS server replies with a certificate message with
   2 certificates.  The DER encoding of the first certificate is 1209
   bytes.

   30 82 04 b5 30 82 04 5a a0 03 02 01 02 02 10 04 7f a1 e3 19 28 ee 40
   3b a0 b8 3a 39 56 73 fc 30 0a 06 08 2a 86 48 ce 3d 04 03 02 30 4a 31
   0b 30 09 06 03 55 04 06 13 02 55 53 31 19 30 17 06 03 55 04 0a 13 10
   43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e 31 20 30 1e 06 03 55
   04 03 13 17 43 6c 6f 75 64 66 6c 61 72 65 20 49 6e 63 20 45 43 43 20
   43 41 2d 33 30 1e 17 0d 32 30 30 37 32 39 30 30 30 30 30 30 5a 17 0d
   32 31 30 37 32 39 31 32 30 30 30 30 5a 30 6d 31 0b 30 09 06 03 55 04
   06 13 02 55 53 31 0b 30 09 06 03 55 04 08 13 02 43 41 31 16 30 14 06
   03 55 04 07 13 0d 53 61 6e 20 46 72 61 6e 63 69 73 63 6f 31 19 30 17
   06 03 55 04 0a 13 10 43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e
   31 1e 30 1c 06 03 55 04 03 13 15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61
   72 65 73 73 6c 2e 63 6f 6d 30 59 30 13 06 07 2a 86 48 ce 3d 02 01 06
   08 2a 86 48 ce 3d 03 01 07 03 42 00 04 96 3e cd d8 4d cd 1b 93 a1 cf
   43 2d 1a 72 17 d6 c6 3b de 33 55 a0 2f 8c fb 5a d8 99 4c d4 4e 20 5f
   15 f6 e3 d2 3b 38 2b a6 49 9b b1 7f 34 1f a5 92 fa 21 86 1f 16 d3 12
   06 63 24 05 fd 70 42 bd a3 82 02 fd 30 82 02 f9 30 1f 06 03 55 1d 23
   04 18 30 16 80 14 a5 ce 37 ea eb b0 75 0e 94 67 88 b4 45 fa d9 24 10
   87 96 1f 30 1d 06 03 55 1d 0e 04 16 04 14 cc 0b 50 e7 d8 37 db f2 43
   f3 85 3d 48 60 f5 3b 39 be 9b 2a 30 2e 06 03 55 1d 11 04 27 30 25 82
   15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61 72 65 73 73 6c 2e 63 6f 6d 82
   0c 77 77 77 2e 69 65 74 66 2e 6f 72 67 30 0e 06 03 55 1d 0f 01 01 ff
   04 04 03 02 07 80 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06 01 05
   05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 7b 06 03 55 1d 1f 04 74
   30 72 30 37 a0 35 a0 33 86 31 68 74 74 70 3a 2f 2f 63 72 6c 33 2e 64
   69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72 65 49
   6e 63 45 43 43 43 41 2d 33 2e 63 72 6c 30 37 a0 35 a0 33 86 31 68 74
   74 70 3a 2f 2f 63 72 6c 34 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f
   43 6c 6f 75 64 66 6c 61 72 65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72
   6c 30 4c 06 03 55 1d 20 04 45 30 43 30 37 06 09 60 86 48 01 86 fd 6c



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   01 01 30 2a 30 28 06 08 2b 06 01 05 05 07 02 01 16 1c 68 74 74 70 73
   3a 2f 2f 77 77 77 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 50 53
   30 08 06 06 67 81 0c 01 02 02 30 76 06 08 2b 06 01 05 05 07 01 01 04
   6a 30 68 30 24 06 08 2b 06 01 05 05 07 30 01 86 18 68 74 74 70 3a 2f
   2f 6f 63 73 70 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 30 40 06 08 2b
   06 01 05 05 07 30 02 86 34 68 74 74 70 3a 2f 2f 63 61 63 65 72 74 73
   2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72
   65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72 74 30 0c 06 03 55 1d 13 01
   01 ff 04 02 30 00 30 82 01 05 06 0a 2b 06 01 04 01 d6 79 02 04 02 04
   81 f6 04 81 f3 00 f1 00 76 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30
   94 56 8e e3 4d 13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 73
   9c 83 5f 8e 00 00 04 03 00 47 30 45 02 21 00 f8 d1 b4 a9 3d 2f 0d 4c
   41 76 df b4 88 bc c7 3b 86 44 3d 7d e0 0e 6a c8 17 4d 89 48 a8 84 36
   68 02 20 29 ff 5a 34 06 8a 24 0c 69 50 27 88 e8 ee 25 ab 7e d2 cb cf
   68 6e ce 7b 5f 96 b4 31 a9 07 02 fa 00 77 00 5c dc 43 92 fe e6 ab 45
   44 b1 5e 9a d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e
   ca 00 00 01 73 9c 83 5f be 00 00 04 03 00 48 30 46 02 21 00 e8 91 c1
   97 bf b0 e3 d3 0c b6 ce e6 0d 94 c3 c7 5f d1 17 53 36 93 11 08 d8 98
   12 d4 d2 9d 81 d0 02 21 00 a1 59 d1 6c 46 47 d1 48 37 57 fc d6 ce 4e
   75 ec 7b 5e f6 57 ef e0 28 f8 e5 cc 47 92 68 2d ac 43 30 0a 06 08 2a
   86 48 ce 3d 04 03 02 03 49 00 30 46 02 21 00 bd 63 cf 4f 7e 5c fe 6c
   29 38 5e a7 1c fb fc 1e 3f 7b 1c d0 72 51 a2 21 f7 77 69 c0 f4 71 df
   ea 02 21 00 b5 c0 6c c4 58 54 fa 30 b2 82 88 b1 d3 bb 9a 66 61 ed 50
   31 72 5b 1a 82 02 e0 da 5b 59 f9 54 02

A.3.1.  Example: C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the first X.509 certificate
   is shown below in CBOR diagnostic format.

/This defines a CBOR Sequence (RFC 8742):/

3,
h'047FA1E31928EE403BA0B83A395673FC',
0,
[
 -4, "US",
 -8, "Cloudflare, Inc.",
 -1, "Cloudflare Inc ECC CA-3"
],
1595980800,
1627560000,
[
 -4, "US",
 -6, "CA",
 -5, "San Francisco",
 -8, "Cloudflare, Inc.",
 -1, "sni.cloudflaressl.com"



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],
1,
h'FD963ECDD84DCD1B93A1CF432D1A7217D6C63BDE3355A02F8CFB5AD8994CD44E20',
[
 7, h'A5CE37EAEBB0750E946788B445FAD9241087961F',
 1, h'CC0B50E7D837DBF243F3853D4860F53B39BE9B2A',
 3, [2, "sni.cloudflaressl.com", 2, "www.ietf.org"],
-2, 1,
 8, [1, 2],
 5, ["http://crl3.digicert.com/CloudflareIncECCCA-3.crl",
     "http://crl4.digicert.com/CloudflareIncECCCA-3.crl"],
 6, [h'6086480186FD6C0101', [1, "https://www.digicert.com/CPS"],  2],
 9, [1, "http://ocsp.digicert.com",
     2, "http://cacerts.digicert.com/CloudflareIncECCCA-3.crt"],
-4, -2,
10, [
    h'F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E3',
    77922190,
    0,
    h'F8D1B4A93D2F0D4C4176DFB488BCC73B86443D7DE00E6AC8174D8948A8843668
    29FF5A34068A240C69502788E8EE25AB7ED2CBCF686ECE7B5F96B431A90702FA',
    h'5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA',
    77922238,
    0,
    h'E891C197BFB0E3D30CB6CEE60D94C3C75FD1175336931108D89812D4D29D81D0
    A159D16C4647D1483757FCD6CE4E75EC7B5EF657EFE028F8E5CC4792682DAC43'
    ]
],
h'BD63CF4F7E5CFE6C29385EA71CFBFC1E3F7B1CD07251A221F77769C0F471DFEA
  B5C06CC45854FA30B28288B1D3BB9A6661ED5031725B1A8202E0DA5B59F95402'

   The size of the CBOR encoding (CBOR sequence) is 783 bytes.

A.4.  Example: CAB Baseline RSA HTTPS X.509 Certificate

   The tools.ietf.org HTTPS server replies with a certificate message
   with 4 certificates.  The DER encoding of the first certificate is
   1647 bytes.

   30 82 06 6b 30 82 05 53 a0 03 02 01 02 02 09 00 a6 a5 5c 87 0e 39 b4
   0e 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0b 05 00 30 81 c6 31 0b 30 09
   06 03 55 04 06 13 02 55 53 31 10 30 0e 06 03 55 04 08 13 07 41 72 69
   7a 6f 6e 61 31 13 30 11 06 03 55 04 07 13 0a 53 63 6f 74 74 73 64 61
   6c 65 31 25 30 23 06 03 55 04 0a 13 1c 53 74 61 72 66 69 65 6c 64 20
   54 65 63 68 6e 6f 6c 6f 67 69 65 73 2c 20 49 6e 63 2e 31 33 30 31 06
   03 55 04 0b 13 2a 68 74 74 70 3a 2f 2f 63 65 72 74 73 2e 73 74 61 72
   66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
   79 2f 31 34 30 32 06 03 55 04 03 13 2b 53 74 61 72 66 69 65 6c 64 20



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   53 65 63 75 72 65 20 43 65 72 74 69 66 69 63 61 74 65 20 41 75 74 68
   6f 72 69 74 79 20 2d 20 47 32 30 1e 17 0d 32 30 31 30 30 31 31 39 33
   38 33 36 5a 17 0d 32 31 31 31 30 32 31 39 33 38 33 36 5a 30 3e 31 21
   30 1f 06 03 55 04 0b 13 18 44 6f 6d 61 69 6e 20 43 6f 6e 74 72 6f 6c
   20 56 61 6c 69 64 61 74 65 64 31 19 30 17 06 03 55 04 03 0c 10 2a 2e
   74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 82 01 22 30 0d 06 09 2a
   86 48 86 f7 0d 01 01 01 05 00 03 82 01 0f 00 30 82 01 0a 02 82 01 01
   00 b1 e1 37 e8 eb 82 d6 89 fa db f5 c2 4b 77 f0 2c 4a de 72 6e 3e 13
   60 d1 a8 66 1e c4 ad 3d 32 60 e5 f0 99 b5 f4 7a 7a 48 55 21 ee 0e 39
   12 f9 ce 0d ca f5 69 61 c7 04 ed 6e 0f 1d 3b 1e 50 88 79 3a 0e 31 41
   16 f1 b1 02 64 68 a5 cd f5 4a 0a ca 99 96 35 08 c3 7e 27 5d d0 a9 cf
   f3 e7 28 af 37 d8 b6 7b dd f3 7e ae 6e 97 7f f7 ca 69 4e cc d0 06 df
   5d 27 9b 3b 12 e7 e6 fe 08 6b 52 7b 82 11 7c 72 b3 46 eb c1 e8 78 b8
   0f cb e1 eb bd 06 44 58 dc 83 50 b2 a0 62 5b dc 81 b8 36 e3 9e 7c 79
   b2 a9 53 8a e0 0b c9 4a 2a 13 39 31 13 bd 2c cf a8 70 cf 8c 8d 3d 01
   a3 88 ae 12 00 36 1d 1e 24 2b dd 79 d8 53 01 26 ed 28 4f c9 86 94 83
   4e c8 e1 14 2e 85 b3 af d4 6e dd 69 46 af 41 25 0e 7a ad 8b f2 92 ca
   79 d9 7b 32 4f f7 77 e8 f9 b4 4f 23 5c d4 5c 03 ae d8 ab 3a ca 13 5f
   5d 5d 5d a1 02 03 01 00 01 a3 82 02 e1 30 82 02 dd 30 0c 06 03 55 1d
   13 01 01 ff 04 02 30 00 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06
   01 05 05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 0e 06 03 55 1d 0f
   01 01 ff 04 04 03 02 05 a0 30 3d 06 03 55 1d 1f 04 36 30 34 30 32 a0
   30 a0 2e 86 2c 68 74 74 70 3a 2f 2f 63 72 6c 2e 73 74 61 72 66 69 65
   6c 64 74 65 63 68 2e 63 6f 6d 2f 73 66 69 67 32 73 31 2d 32 34 32 2e
   63 72 6c 30 63 06 03 55 1d 20 04 5c 30 5a 30 4e 06 0b 60 86 48 01 86
   fd 6e 01 07 17 01 30 3f 30 3d 06 08 2b 06 01 05 05 07 02 01 16 31 68
   74 74 70 3a 2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72
   66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
   79 2f 30 08 06 06 67 81 0c 01 02 01 30 81 82 06 08 2b 06 01 05 05 07
   01 01 04 76 30 74 30 2a 06 08 2b 06 01 05 05 07 30 01 86 1e 68 74 74
   70 3a 2f 2f 6f 63 73 70 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e
   63 6f 6d 2f 30 46 06 08 2b 06 01 05 05 07 30 02 86 3a 68 74 74 70 3a
   2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72 66 69 65 6c
   64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72 79 2f 73 66
   69 67 32 2e 63 72 74 30 1f 06 03 55 1d 23 04 18 30 16 80 14 25 45 81
   68 50 26 38 3d 3b 2d 2c be cd 6a d9 b6 3d b3 66 63 30 2b 06 03 55 1d
   11 04 24 30 22 82 10 2a 2e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67
   82 0e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 1d 06 03 55 1d 0e
   04 16 04 14 ad 8a b4 1c 07 51 d7 92 89 07 b0 b7 84 62 2f 36 55 7a 5f
   4d 30 82 01 06 06 0a 2b 06 01 04 01 d6 79 02 04 02 04 81 f7 04 81 f4
   00 f2 00 77 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30 94 56 8e e3 4d
   13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 74 e5 ac 71 13 00
   00 04 03 00 48 30 46 02 21 00 8c f5 48 52 ce 56 35 43 39 11 cf 10 cd
   b9 1f 52 b3 36 39 22 3a d1 38 a4 1d ec a6 fe de 1f e9 0f 02 21 00 bc
   a2 25 43 66 c1 9a 26 91 c4 7a 00 b5 b6 53 ab bd 44 c2 f8 ba ae f4 d2
   da f2 52 7c e6 45 49 95 00 77 00 5c dc 43 92 fe e6 ab 45 44 b1 5e 9a
   d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e ca 00 00 01
   74 e5 ac 72 3c 00 00 04 03 00 48 30 46 02 21 00 a5 e0 90 6e 63 e9 1d



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   4f dd ef ff 03 52 b9 1e 50 89 60 07 56 4b 44 8a 38 28 f5 96 dc 6b 28
   72 6d 02 21 00 fc 91 ea ed 02 16 88 66 05 4e e1 8a 2e 53 46 c4 cc 51
   fe b3 fa 10 a9 1d 2e db f9 91 25 f8 6c e6 30 0d 06 09 2a 86 48 86 f7
   0d 01 01 0b 05 00 03 82 01 01 00 14 04 3f a0 be d2 ee 3f a8 6e 3a 1f
   78 8e a0 4c 35 53 0f 11 06 1f ff 60 a1 6d 0b 83 e9 d9 2a db b3 3f 9d
   b3 d7 e0 59 4c 19 a8 e4 19 a5 0c a7 70 72 77 63 d5 fe 64 51 0a d2 7a
   d6 50 a5 8a 92 38 ec cb 2f 0f 5a c0 64 58 4d 5c 06 b9 73 63 68 27 8b
   89 34 dc 79 c7 1d 3a fd 34 5f 83 14 41 58 49 80 68 29 80 39 8a 86 72
   69 cc 79 37 ce e3 97 f7 dc f3 95 88 ed 81 03 29 00 d2 a2 c7 ba ab d6
   3a 8e ca 09 0b d9 fb 39 26 4b ff 03 d8 8e 2d 3f 6b 21 ca 8a 7d d8 5f
   fb 94 ba 83 de 9c fc 15 8d 61 fa 67 2d b0 c7 db 3d 25 0a 41 4a 85 d3
   7f 49 46 37 3c f4 b1 75 d0 52 f3 dd c7 66 f1 4b fd aa 00 ed bf e4 7e
   ed 01 ec 7b e4 f6 46 fc 31 fd 72 fe 03 d2 f2 65 af 4d 7e e2 81 9b 7a
   fd 30 3c f5 52 f4 05 34 a0 8a 3e 19 41 58 c8 a8 e0 51 71 84 09 15 ae
   ec a5 77 75 fa 18 f7 d5 77 d5 31 cc c7 2d

A.4.1.  Example: C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the first X.509 certificate
   is shown below in CBOR diagnostic format.

/This defines a CBOR Sequence (RFC 8742):/

3,
h'A6A55C870E39B40E',
23,
[
 -4, "US",
 -6, "Arizona",
 -5, "Scottsdale",
 -8, "Starfield Technologies, Inc.",
 -9, "http://certs.starfieldtech.com/repository/",
 -1, "Starfield Secure Certificate Authority - G2"
],
1601581116,
1635881916,
[
  -9, "Domain Control Validated",
   1, "*.tools.ietf.org"
],
0,
h'B1E137E8EB82D689FADBF5C24B77F02C4ADE726E3E1360D1A8661EC4AD3D3260
  E5F099B5F47A7A485521EE0E3912F9CE0DCAF56961C704ED6E0F1D3B1E508879
  3A0E314116F1B1026468A5CDF54A0ACA99963508C37E275DD0A9CFF3E728AF37
  D8B67BDDF37EAE6E977FF7CA694ECCD006DF5D279B3B12E7E6FE086B527B8211
  7C72B346EBC1E878B80FCBE1EBBD064458DC8350B2A0625BDC81B836E39E7C79
  B2A9538AE00BC94A2A13393113BD2CCFA870CF8C8D3D01A388AE1200361D1E24
  2BDD79D8530126ED284FC98694834EC8E1142E85B3AFD46EDD6946AF41250E7A



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  AD8BF292CA79D97B324FF777E8F9B44F235CD45C03AED8AB3ACA135F5D5D5DA1',
[
-4, -2,
 8, [ 1, 2 ],
 -2, 5,
 5, ["http://crl.starfieldtech.com/sfig2s1-242.crl"],
 6, [ h'6086480186fd6e01071701',
      [1, "http://certificates.starfieldtech.com/repository/"], 1 ],
 9, [ 1, "http://ocsp.starfieldtech.com/",
      2, "http://certificates.starfieldtech.com/repository/sfig2.crt" ],
 7, h'254581685026383D3B2D2CBECD6AD9B63DB36663',
 3, [ 2, "*.tools.ietf.org", 2, "tools.ietf.org" ],
 1, h'AD8AB41C0751D7928907B0B784622F36557A5F4D',
10, [
    h'F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E3',
    1715,
    0,
    h'8CF54852CE5635433911CF10CDB91F52B33639223AD138A41DECA6FEDE1FE90F
      BCA2254366C19A2691C47A00B5B653ABBD44C2F8BAAEF4D2DAF2527CE6454995',
    h'5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA',
    2012,
    0,
    h'A5E0906E63E91D4FDDEFFF0352B91E50896007564B448A3828F596DC6B28726D
      FC91EAED02168866054EE18A2E5346C4CC51FEB3FA10A91D2EDBF99125F86CE6'
    ]
],
h'14043FA0BED2EE3FA86E3A1F788EA04C35530F11061FFF60A16D0B83E9D92ADB
  B33F9DB3D7E0594C19A8E419A50CA770727763D5FE64510AD27AD650A58A9238
  ECCB2F0F5AC064584D5C06B9736368278B8934DC79C71D3AFD345F8314415849
  80682980398A867269CC7937CEE397F7DCF39588ED81032900D2A2C7BAABD63A
  8ECA090BD9FB39264BFF03D88E2D3F6B21CA8A7DD85FFB94BA83DE9CFC158D61
  FA672DB0C7DB3D250A414A85D37F4946373CF4B175D052F3DDC766F14BFDAA00
  EDBFE47EED01EC7BE4F646FC31FD72FE03D2F265AF4D7EE2819B7AFD303CF552
  F40534A08A3E194158C8A8E05171840915AEECA57775FA18F7D577D531CCC72D'

   The size of the CBOR encoding (CBOR sequence) is 1245 bytes.

Acknowledgments

   The authors want to thank Henk Birkholz, Corey Bonnell, Carsten
   Bormann, Russ Housley, Olle Johansson, Benjamin Kaduk, Ilari
   Liusvaara, Laurence Lundblade, Francesca Palombini, Thomas Peterson,
   Michael Richardson, Stefan Santesson, Jim Schaad, Brian Sipos, Rene
   Struik, Fraser Tweedale, and Paul Wouters for reviewing and
   commenting on intermediate versions of the draft and help with
   GitHub.





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Contributors

   Special acknowledgement goes to Lijun Liao for his careful review and
   many detailed improvement proposals.

Authors' Addresses

   John Preuß Mattsson
   Ericsson AB
   Email: john.mattsson@ericsson.com


   Göran Selander
   Ericsson AB
   Email: goran.selander@ericsson.com


   Shahid Raza
   University of Glasgow
   Email: shahid.raza@glasgow.ac.uk


   Joel Höglund
   RISE AB
   Email: joel.hoglund@ri.se


   Martin Furuhed
   IN Groupe
   Email: martin.furuhed@ingroupe.com





















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