



jose                                                            M. Jones
Internet-Draft                                    Self-Issued Consulting
Intended status: Standards Track                                D. Waite
Expires: 8 January 2026                                        J. Miller
                                                           Ping Identity
                                                             7 July 2025


                         JSON Proof Algorithms
                draft-ietf-jose-json-proof-algorithms-10

Abstract

   The JSON Proof Algorithms (JPA) specification registers cryptographic
   algorithms and identifiers to be used with the JSON Web Proof, JSON
   Web Key (JWK), and COSE specifications.  It defines IANA registries
   for these identifiers.

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
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 8 January 2026.

Copyright Notice

   Copyright (c) 2025 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/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.



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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Algorithm Basics  . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Issue . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.2.  Confirm . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.3.  Present . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.4.  Verify  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Algorithm Specifications  . . . . . . . . . . . . . . . . . .   6
     6.1.  Single Use  . . . . . . . . . . . . . . . . . . . . . . .   6
       6.1.1.  JWS Algorithm . . . . . . . . . . . . . . . . . . . .   6
       6.1.2.  Holder Setup  . . . . . . . . . . . . . . . . . . . .   7
       6.1.3.  Issuer Setup  . . . . . . . . . . . . . . . . . . . .   7
       6.1.4.  Signing Payloads  . . . . . . . . . . . . . . . . . .   7
       6.1.5.  Issuer Protected Header . . . . . . . . . . . . . . .   7
       6.1.6.  Payloads  . . . . . . . . . . . . . . . . . . . . . .   8
       6.1.7.  Proof . . . . . . . . . . . . . . . . . . . . . . . .   8
       6.1.8.  Presentation Protected Header
               #{presentation-protected-header}  . . . . . . . . . .   8
       6.1.9.  Presentation  . . . . . . . . . . . . . . . . . . . .   9
       6.1.10. Verification of Presentation  . . . . . . . . . . . .   9
       6.1.11. JPA Registration  . . . . . . . . . . . . . . . . . .  10
     6.2.  Presentation Internal Representation  . . . . . . . . . .  10
     6.3.  BBS . . . . . . . . . . . . . . . . . . . . . . . . . . .  11
       6.3.1.  JPA Algorithms  . . . . . . . . . . . . . . . . . . .  11
       6.3.2.  Key Format  . . . . . . . . . . . . . . . . . . . . .  12
       6.3.3.  Issuance  . . . . . . . . . . . . . . . . . . . . . .  12
       6.3.4.  Issuance Proof Verification . . . . . . . . . . . . .  12
       6.3.5.  Presentation  . . . . . . . . . . . . . . . . . . . .  12
       6.3.6.  Presentation Verification . . . . . . . . . . . . . .  13
     6.4.  Message Authentication Code . . . . . . . . . . . . . . .  13
       6.4.1.  Holder Setup  . . . . . . . . . . . . . . . . . . . .  14
       6.4.2.  Issuer Setup  . . . . . . . . . . . . . . . . . . . .  14
       6.4.3.  Combined MAC Representation . . . . . . . . . . . . .  15
       6.4.4.  Issuer Protected Header . . . . . . . . . . . . . . .  16
       6.4.5.  Issuer Proof  . . . . . . . . . . . . . . . . . . . .  16
       6.4.6.  Presentation Protected Header . . . . . . . . . . . .  16
       6.4.7.  Presentation Proof  . . . . . . . . . . . . . . . . .  16
       6.4.8.  Verification of the Presentation Proof  . . . . . . .  17
       6.4.9.  JPA Registration  . . . . . . . . . . . . . . . . . .  18
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
     8.1.  JSON Web Proof Algorithms Registry  . . . . . . . . . . .  19
       8.1.1.  Registration Template . . . . . . . . . . . . . . . .  20
       8.1.2.  Initial Registry Contents . . . . . . . . . . . . . .  21



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         8.1.2.1.  Single-Use JWP using ES256 Algorithm  . . . . . .  21
         8.1.2.2.  Single-Use JWP using ES384 Algorithm  . . . . . .  21
         8.1.2.3.  Single-Use JWP using ES512 Algorithm  . . . . . .  21
         8.1.2.4.  BBS using SHA-256 Algorithm . . . . . . . . . . .  21
         8.1.2.5.  MAC-H256 Algorithm  . . . . . . . . . . . . . . .  22
         8.1.2.6.  MAC-H384 Algorithm  . . . . . . . . . . . . . . .  22
         8.1.2.7.  MAC-H512 Algorithm  . . . . . . . . . . . . . . .  22
         8.1.2.8.  MAC-K25519 Algorithm  . . . . . . . . . . . . . .  23
         8.1.2.9.  MAC-K448 Algorithm  . . . . . . . . . . . . . . .  23
         8.1.2.10. MAC-H256K Algorithm . . . . . . . . . . . . . . .  23
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  23
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  23
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  24
   Appendix A.  Example JWPs . . . . . . . . . . . . . . . . . . . .  25
     A.1.  Example JSON-Serialized Single-Use JWP  . . . . . . . . .  25
     A.2.  Example CBOR-Serialized Single-Use CPT  . . . . . . . . .  30
     A.3.  Example BBS JWP . . . . . . . . . . . . . . . . . . . . .  34
     A.4.  Example MAC JWP . . . . . . . . . . . . . . . . . . . . .  36
   Appendix B.  Acknowledgements . . . . . . . . . . . . . . . . . .  41
   Appendix C.  Document History . . . . . . . . . . . . . . . . . .  41
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  44

1.  Introduction

   The JSON Web Proof (JWP) [I-D.ietf-jose-json-web-proof] draft
   establishes a new secure container format that supports selective
   disclosure and unlinkability using Zero-Knowledge Proofs (ZKPs) or
   other cryptographic algorithms.

   |  Editor's Note: This draft is still early and incomplete.  There
   |  will be significant changes to the algorithms as currently defined
   |  here.  Please do not use any of these definitions or examples for
   |  anything except personal experimentation and learning.
   |  Contributions and feedback are welcomed at https://github.com/
   |  ietf-wg-jose/json-web-proof (https://github.com/ietf-wg-jose/json-
   |  web-proof).

2.  Conventions and Definitions

   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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   The roles of "issuer", "holder", and "verifier" are used as defined
   by the VC Data Model [VC-DATA-MODEL-2.0].  The term "presentation" is
   also used as defined by this source, but the term "credential" is
   avoided in this specification to minimize confusion with other
   definitions.

3.  Terminology

   The terms "JSON Web Signature (JWS)", "Base64url Encoding", "Header
   Parameter", "JOSE Header", "JWS Payload", "JWS Signature", and "JWS
   Protected Header" are defined by [RFC7515].

   The terms "JSON Web Proof (JWP)", "JWP Payload", "JWP Proof", and
   "JWP Protected Header" are defined by [I-D.ietf-jose-json-web-proof].

   These terms are defined by this specification:

   Stable Key:  An asymmetric key-pair used by an issuer that is also
      shared via an out-of-band mechanism to a verifier to validate the
      signature.
   Issuer Ephemeral Key:  An asymmetric key-pair that is generated for
      one-time use by an issuer and never stored or used again outside
      of the creation of a single JWP.
   Holder Presentation Key:  An asymmetric key-pair that is generated by
      a holder and used to ensure that a presentation is not able to be
      replayed by any other party.

4.  Background

   JWP defines a container binding together a protected header, one or
   more payloads, and a cryptographic proof.  It does not define any
   details about the interactions between an application and the
   cryptographic libraries that implement proof-supporting algorithms.

   Due to the nature of ZKPs, this specification also documents the
   subtle but important differences in proof algorithms versus those
   defined by the JSON Web Algorithms [RFC7518].  These differences help
   support more advanced capabilities such as blinded signatures and
   predicate proofs.

5.  Algorithm Basics

   The four principal interactions that every proof algorithm MUST
   support are issue (#issue), confirm (#confirm), present (#present),
   and verify (#verify).






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5.1.  Issue

   The JWP is first created as the output of a JPA's issue operation.

   Every algorithm MUST support a JSON issuer protected header along
   with one or more octet string payloads.  The algorithm MAY support
   using additional items provided by the holder for issuance such as
   blinded payloads, keys for replay prevention, etc.

   All algorithms MUST provide integrity protection for the issuer
   header and all payloads and MUST specify all digest and/or hash2curve
   methods used.

5.2.  Confirm

   Performed by the holder to validate that the issued JWP is correctly
   formed and protected.

   Each algorithm MAY support using additional input items options, such
   as those sent to the issuer for issuance.  After confirmation, an
   algorithm MAY return a modified JWP for serialized storage without
   the local state (such as with blinded payloads now unblinded).

   The algorithm MUST fully verify the issued proof value against the
   issuer protected header and all payloads.  If given a presented JWP
   instead of an issued one, the confirm process MUST return an error.

5.3.  Present

   Used to apply any selective disclosure choices and perform any
   unlinkability transformations, as well as to show binding.

   An algorithm MAY support additional input options from the requesting
   party, such as for predicate proofs and verifiable computation
   requests.

   Every algorithm MUST support the ability to hide any or all payloads.
   It MUST always include the issuer protected header unmodified in the
   presentation.

   The algorithm MUST replace the issued proof value and generate a new
   presented proof value.  It also MUST include a new presentation
   protected header that provides replay protection.








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5.4.  Verify

   Performed by the verifier to verify the protected headers along with
   any disclosed payloads and/or assertions about them from the proving
   party, while also verifying they are the same payloads and ordering
   as witnessed by the issuer.

   The algorithm MUST verify the integrity of all disclosed payloads and
   MUST also verify the integrity of both the issuer and presentation
   protected headers.

   If the presented proof contains any assertions about the hidden
   payloads, the algorithm MUST also verify all of those assertions.  It
   MAY support additional options, such as those sent to the holder to
   generate the presentation.

   If given an issued JWP for verification, the algorithm MUST return an
   error.

6.  Algorithm Specifications

   This section defines how to use specific algorithms for JWPs.

6.1.  Single Use

   The Single Use (SU) algorithm is based on composing multiple
   traditional asymmetric signatures into a single JWP proof.  It
   enables a very simple form of selective disclosure without requiring
   any advanced cryptographic techniques.

   It does not support unlinkability if the same JWP is presented
   multiple times, therefore when privacy is required the holder will
   need to interact with the issuer again to receive new single-use JWPs
   (dynamically or in batches).

6.1.1.  JWS Algorithm

   The Single Use algorithm uses multiple signing keys to protect the
   protected header as well as individual payloads of an Issued JWP.
   The issuer uses a stable public key to sign each protected header,
   and a per-JWP ephemeral key (conveyed within the protected header) to
   protect the individual payloads.  These signatures are all created
   using the same Asymmetric Algorithm, with the JOSE and COSE name/
   label of this algorithm being part of registration for a fully-
   specified Single Use algorithm identifier.






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   The issuer protected header also conveys a holder presentation key,
   an ephemeral asymmetric key meant to only be used for presenting a
   single JWP.  The fully-specified algorithm the holder must use for
   presentations is also included.  This algorithm MAY be different from
   the algorithm used by the issuer.

   The chosen algorithms MUST be asymmetric signing algorithms, so that
   each signature can be verified without sharing any private values
   between the parties.

6.1.2.  Holder Setup

   In order to support the protection of a presentation by a holder to a
   verifier, the holder MUST use a Holder Presentation Key during the
   issuance and the presentation of every Single Use JWP.  This Holder
   Presentation Key MUST be generated and used for only one JWP if
   unlinkability is desired.

   The issuer MUST verify that the holder has possession of this key.
   The holder-issuer communication to exchange this information is out
   of scope of this specification, but can be accomplished by the holder
   using this key to generate a JWS that signs a value the issuer can
   verify as unique.

   The issuer MUST determine an appropriate holder presentation
   algorithm corresponding to the holder presentation key.  If the
   holder and verifier cannot be assumed to know this algorithm is the
   appropriate choice for a given holder presentation key, this value
   MUST be conveyed in the hpa issuer protected header.

6.1.3.  Issuer Setup

   To create a Single Use JWP, the issuer first generates a unique
   Ephemeral Key using the selected internal algorithm.  This key-pair
   will be used to sign each of the payloads of a single JWP and then
   discarded.

6.1.4.  Signing Payloads

   Each individual payload is signed using the selected internal
   algorithm using the Ephemeral Key.

6.1.5.  Issuer Protected Header

   The Issuer's Ephemeral Key MUST be included via the Issuer Ephemeral
   Key header parameter.





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   The Holder's Presentation Key MUST be included via the Holder
   Presentation Key header parameter.

   The Holder's Presentation Algorithm MUST be included via the Holder
   Presentation Algorithm header parameter unless there is another way
   for the holder and verifier to unambiguously determine the
   appropriate algorithm to use.

   The Issuer Protected Header is signed using the appropriate internal
   signing algorithm for the given fully-specified single use algorithm,
   using the issuer's Stable Key.

6.1.6.  Payloads

   Each JWP payload is processed in order and signed using the given JWA
   using the issuer's Ephemeral Key.

6.1.7.  Proof

   The proof value is an octet string array.  The first entry is the
   octet string of the issuer protected header signature, with an
   additional entry for each payload signature.

6.1.8.  Presentation Protected Header #{presentation-protected-header}

   To generate a new presentation, the holder first creates a
   presentation protected header that is specific to the verifier being
   presented to.  This header MUST contain a parameter that both the
   holder and verifier trust as being unique and non-replayable.  Use of
   the nonce header parameter is RECOMMENDED for this purpose.

   This specification registers the nonce header parameter for the
   presentation protected header that contains a string value either
   generated by the verifier or derived from values provided by the
   verifier.  When present, the verifier MUST ensure the nonce value
   matches during verification.

   The presentation protected header MAY contain other header parameters
   that are either provided by the verifier or by the holder.  These
   presentation header parameters SHOULD NOT contain values that are
   common across multiple presentations and SHOULD be unique to a single
   presentation and verifier.

   The presentation protected header MUST contain the same Algorithm
   protected header as the issuer protected header.  The Holder
   Presentation Algorithm protected header MUST NOT be included.





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6.1.9.  Presentation

   The holder derives a new proof as part of presentation.  The holder
   will also use these components to generate a presentation internal
   representation (#presentation-internal-representation).  The number
   of components depends on the number of payloads which are being
   disclosed in the presented JWP.

   The first proof component will be the signature over the issuer
   protected header made by the issuer's Stable Key.

   For each payload which is to be disclosed, the corresponding payload
   signature (from the issued JWP) is included as a subsequent proof
   component.  If the payload is being omitted, the corresponding
   payload signature is omitted from the proof components.

   The holder protected header, issuer protected header, payload slots
   (distinguishing which are being disclosed) and these proof components
   are inputs to determine the presentation internal representation.

   The holder's signature over the presentation internal representation
   (using the holder's private key and the holder presentation
   algorithm) is then included as one additional proof component in the
   final presentation.

   For example, if only the second and fifth of five payloads are being
   disclosed, then the proof at this stage will consist of three values:

   1.  The issuer's signature over the issuer protected header
   2.  The payload signature corresponding to the second payload
   3.  The payload signature corresponding to the fifth payload.

   The presentation internal representation would be calculated with
   these three proof components, while the final presentation would have
   an additional fourth component containing the signature using the
   holder's private key.

   Since the individual signatures in the proof value are unique and
   remain unchanged across multiple presentations, a Single Use JWP
   SHOULD only be presented a single time to each verifier in order for
   the holder to remain unlinkable across multiple presentations.

6.1.10.  Verification of Presentation

   Verification is performed using the following steps.






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   1.  Check that the number of proof components is appropriate for the
       number of disclosed payloads.  There MUST be two more proof
       components than disclosed payloads.
   2.  Verify the first proof component is a valid signature over issuer
       protected header octets, using the issuer's stable key.
   3.  Extract the holder presentation key and holder presentation
       algorithm (if present) from the issuer protected header.
   4.  Omitting the final payload component, calculate the presentation
       internal representation (#presentation-internal-representation).
   5.  Verify the final proof component is a valid signature over the
       presentation internal binary form, using the holder's
       presentation key and the extracted (or otherwise determined)
       holder presentation algorithm.
   6.  For each remaining proof component, verify they form a valid
       signature over each disclosed payload in sequence, using the
       issuer's ephemeral key.

6.1.11.  JPA Registration

   The proposed JWP alg value is of the format "SU-" appended with the
   relevant JWS alg value for the chosen public and ephemeral key-pair
   algorithm, for example "SU-ES256".

6.2.  Presentation Internal Representation

   Some algorithms (such as Single use and MAC) use a holder key to
   provide integrity over the presentation.  For these algorithms, an
   internal binary form of the presentation must be generated both for
   signing by the holder, and for verification by the verifier.  Other
   algorithms MAY use this same form for consistency.

   The instructions for creating this binary representation will also
   create well-formed CBOR, although this data is not meant to be shared
   outside the implementing algorithm.  Instead, it focuses on
   simplicity of generation by the holder and verifier implementations.
   Although CBOR has multiple representations of the same underlying
   information, this same octet string MUST be generated by an
   implementation.

   When a length or count is added by the steps below, it is added as
   its 8 byte, network-ordered representation.  For example, the length
   of a 1,234 byte payload would have a length representation of 0x00 00
   00 00 00 00 04 D2.

   The binary representation is created by appending data into a single
   octet string in the following order:

   1.   0x84 5B



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   2.   The length and octets of the presentation protected header

   3.   0x5B

   4.   The length and octets of the issuer protected header

   5.   0x9B

   6.   The number of payload slots in the issued message

   7.   For each payload representation:

        *  If the payload is being omitted, the value 0xF6

        *  Otherwise:

           1.  0x5B
           2.  The length and octets of the payload

   8.   0x9B

   9.   The number of proof components as specified by the algorithm

   10.  For each proof component, append:

        1.  0x5B
        2.  The length and octets of the proof component

6.3.  BBS

   The BBS Signature Scheme [I-D.irtf-cfrg-bbs-signatures] is under
   active development within the CRFG.

   This algorithm supports both selective disclosure and unlinkability,
   enabling the holder to generate multiple presentations from one
   issued JWP without a verifier being able to correlate those
   presentations together based on the proof.

6.3.1.  JPA Algorithms

   The BBS algorithm corresponds to a ciphersuite identifier of
   BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_.









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6.3.2.  Key Format

   The key used for the BBS algorithm is an elliptic curve-based key
   pair, specifically against the G_2 subgroup of a pairing friendly
   curve.  Additional details on key generation can be found in
   Section 3.4.  The JWK and Cose Key Object representations of the key
   are detailed in [I-D.ietf-cose-bls-key-representations].

   There is no additional holder presentation key necessary for
   presentation proofs.

6.3.3.  Issuance

   Issuance is performed using the Sign operation from Section 3.5.1 of
   [I-D.irtf-cfrg-bbs-signatures].  This operation utilizes the issuer's
   BLS12-381 G2 key pair as SK and PK, along with desired protected
   header octets as header, and the array of payload octet string as
   messages.

   The octets resulting from this operation form a single octet string
   in the issuance proof array, to be used along with the protected
   header and payloads to serialize the JWP.

6.3.4.  Issuance Proof Verification

   Holder verification of the signature on issuance form is performed
   using the Verify operation from [@!I-D.irtf-cfrg-bbs-signatures,
   section 3.5.2].

   This operation utilizes the issuer's public key as PK, the proof as
   signature, the protected header octets as header and the array of
   payload octets as messages.

6.3.5.  Presentation

   Derivation of a presentation is done by the holder using the ProofGen
   operation from Section 3.5.3 of [I-D.irtf-cfrg-bbs-signatures].

   This operation utilizes the issuer's public key as PK, the issuer
   protected header as header, the issuance proof as signature, the
   issuance payloads as messages, and the holder's presentation
   protected header as ph.

   The operation also takes a vector of indexes into messages,
   describing which payloads the holder wishes to disclose.  All
   payloads are required for proof generation, but only these indicated
   payloads will be required to be disclosed for later proof
   verification.



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   The output of this operation is the presentation proof, as a single
   octet string.

   Presentation serialization leverages the two protected headers and
   presentation proof, along with the disclosed payloads.  Non-disclosed
   payloads are represented with the absent value of null in CBOR
   serialization and a zero-length string in compact serialization.

6.3.6.  Presentation Verification

   Verification of a presentation is done by the verifier using the
   ProofVerify operation from [@!I-D.irtf-cfrg-bbs-signatures,
   Section 3.5.4].

   This operation utilizes the issuer's public key as PK, the issuer
   protected header as header, the issuance proof as signature, the
   holder's presentation protected header as ph, and the payloads as
   disclosed_messages.

   In addition, the disclosed_indexes scalar array is calculated from
   the payloads provided.  Values disclosed in the presented payloads
   have a zero-based index in this array, while the indices of absent
   payloads are omitted.

6.4.  Message Authentication Code

   The Message Authentication Code (MAC) JPA uses a MAC to both generate
   ephemeral secrets and to authenticate payloads, along with an
   asymmetric signature to provide integrity to the issued JWP.

   The holder can manipulate which payloads are disclosed from the
   issued JWP, and uses the Holder Presentation Key to create a
   presentation.  The signature created from the Holder Presentation Key
   MAY use a different algorithm than the Issuer used to sign the issued
   form.

   Like the Single Use algorithm family, it also does not support
   unlinkability if the same JWP is presented multiple times and
   requires an individually issued JWP for each presentation in order to
   fully protect privacy.  When compared to the JWS approach, using a
   MAC requires less computation but can result in potentially larger
   presentation proof values.









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   The design is intentionally minimal and only involves using a single
   standardized MAC method instead of a mix of MAC/hash methods or a
   custom hash-based construct.  It is able to use any published
   cryptographic MAC method such as HMAC [RFC2104] or KMAC
   (https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
   NIST.SP.800-185.pdf).  It uses traditional public key-based
   signatures to verify the authenticity of the issuer and holder.

6.4.1.  Holder Setup

   In order to support the protection of a presentation by a holder to a
   verifier, the holder MUST use a Holder Presentation Key during the
   issuance and the presentation of every MAC JWP.  This Holder
   Presentation Key MUST be generated and used for only one JWP if
   unlinkability is desired.

   The issuer MUST verify that the holder has possession of this key.
   The holder-issuer communication to exchange this information is out
   of scope of this specification, but can be accomplished by the holder
   using this key to generate a JWS that signs a value the issuer can
   verify as unique.

   The holder's presentation key MUST be included in the issuer's
   protected header using the Holder Presentation Key header parameter.

   The issuer MUST determine an appropriate holder presentation
   algorithm corresponding to the holder presentation key.  If the
   holder and verifier cannot be assumed to know this algorithm is the
   appropriate choice for a given holder presentation key, this value
   MUST be conveyed in the Holder Protected Algorithm header parameter.

6.4.2.  Issuer Setup

   To use the MAC algorithm, the issuer must have a stable public key
   pair to perform signing.  To start the issuance process, a single
   32-byte random Shared Secret must first be generated.  This value
   will be shared privately with the holder as part of the issuer's JWP
   proof value.

   The Shared Secret is used by both the issuer and holder as the MAC
   method's key to generate a new set of unique ephemeral keys.  These
   keys are then used as the input to generate a MAC that protects each
   payload.








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6.4.3.  Combined MAC Representation

   The combined MAC representation is a single octet string representing
   the MAC values of the issuer protected header, along with each
   payload provided by the issuer.  This representation is signed by the
   issuer, but not shared - parties will recreate this octet string and
   verify the signature to verify the integrity of supplied issuer
   protected header and the integrity of any disclosed payloads.

   The steps below describe a sequential concatenation of binary values
   to generate the Combined MAC Representation.  The instructions for
   generating this octet string will also generate well-formed CBOR,
   although this data is not meant to be shared outside the implementing
   algorithm.  Instead, it focuses on simplicity of generation by the
   issuer, holder, and verifier implementations.  Although CBOR has
   multiple representations of the same underlying information, this
   same octet string MUST be generated by an implementation.

   When a length or count is added by steps in this section, it is added
   as its 8-byte, network-ordered representation.  For example, the
   length of a 1,234-byte payload would have a length representation of
   0x00 00 00 00 00 00 04 D2.

   The holder will a unique key per payload value using a MAC, with the
   Shared Secret as the key and a generated binary value.  This binary
   value is constructed by appending data into a single octet string:

   1.  0x82 67 70 61 79 6C 6F 61 64 1B
   2.  The zero indexed count of the payload slot

   The holder will also compute a corresponding MAC of each payload.
   This MAC uses the unique key above and the payload octet string as
   the value.

   When verifying a presentation, the shared secret will be unavailable
   so the unique key cannot be calculated.  The payload octet string may
   also be omitted in the presentation.  The following instructions
   describe how to get the corresponding MAC of each payload:

   *  If the payload is disclosed, the corresponding proof component (as
      described in MAC Presentation Proof (#mac-presentation-proof))
      will contain the generated unique key.  The payload MAC will be
      calculated using this key and the payload octets as the value.
   *  If the payload is not disclosed, the corresponding proof component
      will be the payload MAC.

   The binary representation is created by appending data into a single
   octet string in the following order:



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   1.  0x82 5B
   2.  The length and octets of the issuer protected header
   3.  0x9B
   4.  The number of payload slots in the issued JWP
   5.  For each payload representation:
       1.  0x5B
       2.  The length and value of the per payload MAC

6.4.4.  Issuer Protected Header

   The Holder's Presentation Key MUST be included via the Holder
   Presentation Key header parameter.

   The Holder's Presentation Algorithm MUST be included via the Holder
   Presentation Algorithm header parameter unless there is another way
   for the holder and verifier to unambiguously determine the
   appropriate algorithm to use.

6.4.5.  Issuer Proof

   The issuer proof consists of two octet strings.

   The first octet string is the issuer signature over the combined MAC
   representation.  The issuer signs the combined MAC representation
   using its stable public key, and the internal signing algorithm for
   the given fully-specified MAC algorithm variant.

   The second octet string is the Shared Secret used to generate the
   per-payload keys for the combined representation.

6.4.6.  Presentation Protected Header

   See the Presentation Protected Header (#presentation-protected-
   header) section given for Single Use algorithms.

6.4.7.  Presentation Proof

   The presentation proof is made of multiple components.

   The first proof component is the issuer signature over the Combined
   MAC Representation, which is provided as the first proof component
   from the issued form.

   There will now be one proof component per payload slot in the issued
   JWP.  These are used by the verifier to reconstruct the combined MAC
   representation without access to the Shared Secret.  The proof
   components are calculated per the instructions used to generate the
   Combined MAC Representation (#combined-mac-representation)



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   If a payload is disclosed, the corresponding proof component will be
   the unique key.

   If a payload is not disclosed, the corresponding proof component will
   be the payload's MAC (using the unique key.)

   The holder protected header, issuer protected header, payload slots
   (distinguishing which are being disclosed) and above proof components
   are inputs to determine the presentation internal representation
   (#presentation-internal-representation).

   The holder's signature over the presentation internal representation
   (using the holder's private key and the holder presentation
   algorithm) is then included as one additional proof component in the
   final presentation.

   The presented form should have two more proof components than payload
   slots in the issued JWP.

   Note that the second component of the issued JWP is a shared secret
   for use by the holder to generate the unique keys used in the
   Combined MAC Representation.  This MUST NOT be included in the
   presentation.

6.4.8.  Verification of the Presentation Proof

   Verification is performed using the following steps.

   1.  Check the number of proof components is appropriate for the
       number of disclosed payloads.  There MUST be two more proof
       components than disclosed payloads.
   2.  Using the fully-specified MAC algorithm in use, use the issuer
       protected header, disclosed payloads, and the proof components
       corresponding to the payloads to regenerate the Combined MAC
       Representation.
   3.  Verify the first proof component is a valid signature over the
       issuer protected header octets, using the issuer's stable key.
   4.  Extract the holder presentation key and holder presentation
       algorithm (if present) from the issuer protected header.
   5.  Omitting the final payload component, calculate the presentation
       internal representation (#presentation-internal-representation).
   6.  Verify the final proof component is a valid signature over the
       presentation internal binary form, using the holder's
       presentation key and the extracted (or otherwise determined)
       holder presentation algorithm.






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6.4.9.  JPA Registration

   Proposed JWP alg value is of the format "MAC-" appended with a unique
   identifier for the set of MAC and signing algorithms used.  Below are
   the initial registrations:

   *  MAC-H256 uses HMAC SHA-256 as the MAC and ECDSA using P-256 and
      SHA-256 for the signatures
   *  MAC-H384 uses HMAC SHA-384 as the MAC and ECDSA using P-384 and
      SHA-384 for the signatures
   *  MAC-H512 uses HMAC SHA-512 as the MAC and ECDSA using P-521 and
      SHA-512 for the signatures
   *  MAC-K25519 uses KMAC SHAKE128 as the MAC and EdDSA using
      Curve25519 for the signatures
   *  MAC-K448 uses KMAC SHAKE256 as the MAC and EdDSA using Curve448
      for the signatures
   *  MAC-H256K uses HMAC SHA-256 as the MAC and ECDSA using secp256k1
      and SHA-256 for the signatures

7.  Security Considerations

   |  Editor's Note: This will follow once the algorithms defined here
   |  have become more stable.

   *  Data minimization of the proof value
   *  Unlinkability of the protected header contents

8.  IANA Considerations

   The following registration procedure is used for all the registries
   established by this specification.

   Values are registered on a Specification Required [RFC5226] basis
   after a three-week review period on the jose-reg-review@ietf.org
   (mailto:jose-reg-review@ietf.org) mailing list, on the advice of one
   or more Designated Experts.  However, to allow for the allocation of
   values prior to publication, the Designated Experts may approve
   registration once they are satisfied that such a specification will
   be published.

   Registration requests sent to the mailing list for review should use
   an appropriate subject (e.g., "Request to register JWP algorithm:
   example").

   Within the review period, the Designated Experts will either approve
   or deny the registration request, communicating this decision to the
   review list and IANA.  Denials should include an explanation and, if
   applicable, suggestions as to how to make the request successful.



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   Registration requests that are undetermined for a period longer than
   21 days can be brought to the IESG's attention (using the
   iesg@ietf.org (mailto:iesg@ietf.org) mailing list) for resolution.

   Criteria that should be applied by the Designated Experts include
   determining whether the proposed registration duplicates existing
   functionality, whether it is likely to be of general applicability or
   useful only for a single application, and whether the registration
   description is clear.

   IANA must only accept registry updates from the Designated Experts
   and should direct all requests for registration to the review mailing
   list.

   It is suggested that multiple Designated Experts be appointed who are
   able to represent the perspectives of different applications using
   this specification, in order to enable broadly informed review of
   registration decisions.  In cases where a registration decision could
   be perceived as creating a conflict of interest for a particular
   Expert, that Expert should defer to the judgment of the other
   Experts.

8.1.  JSON Web Proof Algorithms Registry

   This specification establishes the IANA "JSON Web Proof Algorithms"
   registry for values of the JWP alg (algorithm) parameter in JWP
   Header Parameters.  The registry records the algorithm name, the
   algorithm description, the algorithm usage locations, the
   implementation requirements, the change controller, and a reference
   to the specification that defines it.  The same algorithm name can be
   registered multiple times, provided that the sets of usage locations
   are disjoint.

   It is suggested that the length of the key be included in the
   algorithm name when multiple variations of algorithms are being
   registered that use keys of different lengths and the key lengths for
   each need to be fixed (for instance, because they will be created by
   key derivation functions).  This allows readers of the JSON text to
   more easily make security decisions.

   The Designated Experts should perform reasonable due diligence that
   algorithms being registered either are currently considered
   cryptographically credible or are being registered as Deprecated or
   Prohibited.

   The implementation requirements of an algorithm may be changed over
   time as the cryptographic landscape evolves, for instance, to change
   the status of an algorithm to Deprecated or to change the status of



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   an algorithm from Optional to Recommended+ or Required.  Changes of
   implementation requirements are only permitted on a Specification
   Required basis after review by the Designated Experts, with the new
   specification defining the revised implementation requirements level.

8.1.1.  Registration Template

   Algorithm Name:  Brief descriptive name of the algorithm (e.g.,
      Single-Use JWP using ES256.)  Descriptive names may not match
      other registered names unless the Designated Experts state that
      there is a compelling reason to allow an exception.
   Algorithm JSON Label:  The string label requested (e.g., SU-ES256).
      This label is a case-sensitive ASCII string.  JSON Labels may not
      match other registered labels in a case-insensitive manner unless
      the Designated Experts state that there is a compelling reason to
      allow an exception.
   Algorithm CBOR Label:  The integer label requested (e.g., 1).  CBOR
      Labels may not match other registered labels unless the Designated
      Experts state that there is a compelling reason to allow an
      exception.
   Algorithm Description:  Optional additional information clarifying
      the algorithm.  This may be used for example to document
      additional chosen parameters.
   Algorithm Usage Location(s):  The algorithm usage locations, which
      should be one or more of the values Issued or Presented.  Other
      values may be used with the approval of a Designated Expert.
   JWP Implementation Requirements:  The algorithm implementation
      requirements for JWP, which must be one the words Required,
      Recommended, Optional, Deprecated, or Prohibited.  Optionally, the
      word can be followed by a + or -. The use of + indicates that the
      requirement strength is likely to be increased in a future version
      of the specification.  The use of - indicates that the requirement
      strength is likely to be decreased in a future version of the
      specification.  Any identifiers registered for algorithms that are
      otherwise unsuitable for direct use as JWP algorithms must be
      registered as Prohibited.
   Change Controller:  For Standards Track RFCs, list the "IETF".  For
      others, give the name of the responsible party.  Other details
      (e.g., postal address, email address, home page URI) may also be
      included.
   Specification Document(s):  Reference to the document or documents
      that specify the parameter, preferably including URIs that can be
      used to retrieve copies of the documents.  An indication of the
      relevant sections may also be included but is not required.
   Algorithm Analysis Documents(s):  References to a publication or
      publications in well-known cryptographic conferences, by national
      standards bodies, or by other authoritative sources analyzing the
      cryptographic soundness of the algorithm to be registered.  The



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      Designated Experts may require convincing evidence of the
      cryptographic soundness of a new algorithm to be provided with the
      registration request unless the algorithm is being registered as
      Deprecated or Prohibited.  Having gone through working group and
      IETF review, the initial registrations made by this document are
      exempt from the need to provide this information.

8.1.2.  Initial Registry Contents

8.1.2.1.  Single-Use JWP using ES256 Algorithm

   *  Algorithm Name: Single-Use JWP using ES256
   *  Algorithm JSON Label: SU-ES256
   *  Algorithm CBOR Label: 1
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Recommended
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.1.11 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.2.  Single-Use JWP using ES384 Algorithm

   *  Algorithm Name: Single-Use JWP using ES384
   *  Algorithm JSON Label: SU-ES384
   *  Algorithm CBOR Label: 2
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.1.11 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.3.  Single-Use JWP using ES512 Algorithm

   *  Algorithm Name: Single-Use JWP using ES512
   *  Algorithm JSON Label: SU-ES512
   *  Algorithm CBOR Label: 3
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.1.11 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.4.  BBS using SHA-256 Algorithm

   *  Algorithm Name: BBS using SHA-256
   *  Algorithm JSON Label: BBS
   *  Algorithm CBOR Label: 4




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   *  Algorithm Description: Corresponds to a ciphersuite identifier of
      BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_H2G_HM2S_
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Required
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.3.1 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.5.  MAC-H256 Algorithm

   *  Algorithm Name: MAC-H256
   *  Algorithm JSON Label: MAC-H256
   *  Algorithm CBOR Label: 5
   *  Algorithm Description: MAC-H256 uses HMAC SHA-256 as the MAC, and
      ECDSA using P-256 and SHA-256 for the signatures
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.4.9 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.6.  MAC-H384 Algorithm

   *  Algorithm Name: MAC-H384
   *  Algorithm JSON Label: MAC-H384
   *  Algorithm CBOR Label: 6
   *  Algorithm Description: MAC-H384 uses HMAC SHA-384 as the MAC, and
      ECDSA using P-384 and SHA-384 for the signatures
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.4.9 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.7.  MAC-H512 Algorithm

   *  Algorithm Name: MAC-H512
   *  Algorithm JSON Label: MAC-H512
   *  Algorithm CBOR Label: 7
   *  Algorithm Description: MAC-H512 uses HMAC SHA-512 as the MAC, and
      ECDSA using P-521 and SHA-512 for the signatures
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.4.9 of this specification
   *  Algorithm Analysis Documents(s): n/a





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8.1.2.8.  MAC-K25519 Algorithm

   *  Algorithm Name: MAC-K25519
   *  Algorithm JSON Label: MAC-K25519
   *  Algorithm CBOR Label: 8
   *  Algorithm Description: MAC-K25519 uses KMAC SHAKE128 as the MAC,
      and EdDSA using Curve25519 for the signatures
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.4.9 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.9.  MAC-K448 Algorithm

   *  Algorithm Name: MAC-K448
   *  Algorithm JSON Label: MAC-K448
   *  Algorithm CBOR Label: 9
   *  Algorithm Description: MAC-K448 uses KMAC SHAKE256 as the MAC, and
      EdDSA using Curve448 for the signatures
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.4.9 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.10.  MAC-H256K Algorithm

   *  Algorithm Name: MAC-H256K
   *  Algorithm JSON Label: MAC-H256K
   *  Algorithm CBOR Label: 10
   *  Algorithm Description: MAC-H256K uses HMAC SHA-256 as the MAC, and
      ECDSA using secp256k1 and SHA-256 for the signatures
   *  Algorithm Usage Location(s): Issued, Presented
   *  JWP Implementation Requirements: Optional
   *  Change Controller: IETF
   *  Specification Document(s): Section 6.4.9 of this specification
   *  Algorithm Analysis Documents(s): n/a

9.  References

9.1.  Normative References

   [I-D.ietf-jose-json-web-proof]
              Waite, D., Jones, M. B., and J. Miller, "JSON Web Proof",
              Work in Progress, Internet-Draft, draft-ietf-jose-json-
              web-proof-latest, <https://datatracker.ietf.org/doc/html/
              draft-ietf-jose-json-web-proof>.



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   [I-D.irtf-cfrg-bbs-signatures]
              Looker, T., Kalos, V., Whitehead, A., and M. Lodder, "The
              BBS Signature Scheme", Work in Progress, Internet-Draft,
              draft-irtf-cfrg-bbs-signatures-09, 7 July 2025,
              <https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-
              bbs-signatures-09>.

   [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/info/rfc2119>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/info/rfc7515>.

   [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/info/rfc8174>.

9.2.  Informative References

   [I-D.ietf-cbor-edn-literals]
              Bormann, C., "CBOR Extended Diagnostic Notation (EDN)",
              Work in Progress, Internet-Draft, draft-ietf-cbor-edn-
              literals-17, 12 May 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cbor-
              edn-literals-17>.

   [I-D.ietf-cose-bls-key-representations]
              Looker, T. and M. B. Jones, "Barreto-Lynn-Scott Elliptic
              Curve Key Representations for JOSE and COSE", Work in
              Progress, Internet-Draft, draft-ietf-cose-bls-key-
              representations-06, 18 January 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cose-
              bls-key-representations-06>.

   [I-D.maldant-spice-oidc-cwt]
              Maldant, B., "OpenID Connect standard claims registration
              for CBOR Web Tokens", Work in Progress, Internet-Draft,
              draft-maldant-spice-oidc-cwt-02, 17 March 2025,
              <https://datatracker.ietf.org/doc/html/draft-maldant-
              spice-oidc-cwt-02>.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              DOI 10.17487/RFC2104, February 1997,
              <https://www.rfc-editor.org/info/rfc2104>.



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   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <https://www.rfc-editor.org/info/rfc5226>.

   [RFC7518]  Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
              DOI 10.17487/RFC7518, May 2015,
              <https://www.rfc-editor.org/info/rfc7518>.

   [VC-DATA-MODEL-2.0]
              Sporny, M., Jr, T. T., Herman, I., Cohen, G., and M. B.
              Jones, "Verifiable Credentials Data Model v2.0", 15 May
              2025, <https://www.w3.org/TR/vc-data-model-2.0>.

Appendix A.  Example JWPs

   The following examples use algorithms defined in JSON Proof
   Algorithms and also contain the keys used, so that implementations
   can validate these samples.

A.1.  Example JSON-Serialized Single-Use JWP

   This example uses the Single-Use Algorithm as defined in JSON Proof
   Algorithms to create a JSON Proof Token.  It demonstrates how to
   apply selective disclosure using an array of traditional JWS-based
   signatures.  Unlinkability is only achieved by using each JWP one
   time, as multiple uses are inherently linkable via the traditional
   ECDSA signature embedded in the proof.

   To begin, we need two asymmetric keys for Single Use: one that
   represents the JPT Issuer's stable key and the other is an ephemeral
   key generated by the Issuer just for this JWP.

   This is the Issuer's stable private key used in this example in the
   JWK format:

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "a_H-BwPtMTftwSmvcm7IVc4SXVORAZI7-3s1sJadJJc",
     "y": "CDrp08C0zI8Fnu2_02neoC4DCrDdhZWasbK-86luj08",
     "d": "vewf1OM4w1lPXVc8FjfiDEUL-mRdabs1AhUWIcgTqRc"
   }

                Figure 1: Issuer Private Key (ES256 in JWK)

   This is the ephemeral private key used in this example in the JWK
   format:



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   {
     "kty": "EC",
     "crv": "P-256",
     "x": "NEF-Td43WsKj2mVGfgfxQsqN9pa9ovf2RNc4PYLKqMM",
     "y": "F66_na_oPnr8UX7TthiAJRaEnqo4wRRAXvk3XJTLOBQ",
     "d": "bBUHpA5Bn127BdIX1bRvPbMHq8MYwNM72zPc6pUinQs"
   }

           Figure 2: Issuer Ephemeral Private Key (ES256 in JWK)

   This is the Holder's presentation private key used in this example in
   the JWK format:

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "CIjnk8YTDI-nikYZf8T6z6Z5oA0imfqPHfxGUlWo580",
     "y": "Dbs-DI1_0RKTVqwE9IZRiCfvLF5pVmsOIpo8x1wD-gY",
     "d": "HbSTQhLXQ-UhSSrcINHmZyBFTYUm8jYVv96WRhQkFV4"
   }

          Figure 3: Holder Presentation Private Key (ES256 in JWK)

   The JWP Protected Header declares that the data structure is a JPT
   and the JWP Proof Input is secured using the Single-Use ECDSA
   algorithm with the P-256 curve and SHA-256 digest.  It also includes
   the ephemeral public key, the Holder's presentation public key and
   list of claims used for this JPT.























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   {
     "alg": "SU-ES256",
     "typ": "JPT",
     "iss": "https://issuer.example",
     "hpa": "ES256",
     "claims": [
       "iat",
       "exp",
       "family_name",
       "given_name",
       "email",
       "address",
       "age_over_21"
     ],
     "iek": {
       "kty": "EC",
       "crv": "P-256",
       "x": "NEF-Td43WsKj2mVGfgfxQsqN9pa9ovf2RNc4PYLKqMM",
       "y": "F66_na_oPnr8UX7TthiAJRaEnqo4wRRAXvk3XJTLOBQ"
     },
     "hpk": {
       "kty": "EC",
       "crv": "P-256",
       "x": "CIjnk8YTDI-nikYZf8T6z6Z5oA0imfqPHfxGUlWo580",
       "y": "Dbs-DI1_0RKTVqwE9IZRiCfvLF5pVmsOIpo8x1wD-gY"
     }
   }

             Figure 4: Issuer Protected header (SU-ES256, JSON)

   eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
   mV4YW1wbGUiLCJocGEiOiJFUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbH
   lfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJ
   dLCJpZWsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiJORUYtVGQ0M1dzS2oy
   bVZHZmdmeFFzcU45cGE5b3ZmMlJOYzRQWUxLcU1NIiwieSI6IkY2Nl9uYV9vUG5yOFVYN
   1R0aGlBSlJhRW5xbzR3UlJBWHZrM1hKVExPQlEifSwiaHBrIjp7Imt0eSI6IkVDIiwiY3
   J2IjoiUC0yNTYiLCJ4IjoiQ0lqbms4WVRESS1uaWtZWmY4VDZ6Nlo1b0EwaW1mcVBIZnh
   HVWxXbzU4MCIsInkiOiJEYnMtREkxXzBSS1RWcXdFOUlaUmlDZnZMRjVwVm1zT0lwbzh4
   MXdELWdZIn19

    Figure 5: Encoded Issuer Protected Header (SU-ES256, JSON, encoded)










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   The Single Use algorithm utilizes multiple individual JWS Signatures.
   Each signature value is generated by creating a JWS with a single
   Protected Header with the associated alg value.  In this example, the
   fixed header used for each JWS is the serialized JSON Object
   {"alg":"ES256"}.  This protected header will be used to generate a
   signature over each corresponding payload in the JWP.  The
   corresponding octet value in the proof is the octet string
   (base64url-decoded) value of the signature.

   The final proof value from the Issuer is an array with the octets of
   the header signature, followed by entries for each payload signature.

   [
       1714521600,
       1717199999,
       "Doe",
       "Jay",
       "jaydoe@example.org",
       {
           "formatted": "1234 Main St.\nAnytown, CA 12345\nUSA",
           "street_address": "1234 Main St.",
           "locality": "Anytown",
           "region": "CA",
           "postal_code": 12345,
           "country": "USA"
       },
       true
   ]

                 Figure 6: Issuer payloads (JSON, as array)

   The compact serialization of the same JPT is:



















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   eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
   mV4YW1wbGUiLCJocGEiOiJFUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbH
   lfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJ
   dLCJpZWsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiJORUYtVGQ0M1dzS2oy
   bVZHZmdmeFFzcU45cGE5b3ZmMlJOYzRQWUxLcU1NIiwieSI6IkY2Nl9uYV9vUG5yOFVYN
   1R0aGlBSlJhRW5xbzR3UlJBWHZrM1hKVExPQlEifSwiaHBrIjp7Imt0eSI6IkVDIiwiY3
   J2IjoiUC0yNTYiLCJ4IjoiQ0lqbms4WVRESS1uaWtZWmY4VDZ6Nlo1b0EwaW1mcVBIZnh
   HVWxXbzU4MCIsInkiOiJEYnMtREkxXzBSS1RWcXdFOUlaUmlDZnZMRjVwVm1zT0lwbzh4
   MXdELWdZIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZU
   BleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCB
   DQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9j
   YWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsI
   mNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.pxjdEgByvXszRLN8nNAzLkD9-23FpUcT9PC8GJJ1
   xofOfkIMEftYmK-6UNhxXytVuLx_tBbSvrEOPG5oy1iYFg~FpdvS_bmS74VGnM1PM8VvS
   7Y0WwxeHiNrg5VrkIwNn6A2NcWqMitKpcCZ7RGevmU3v9JJryh3LeayDbDVTuMvg~4BpH
   Kta_iV-nbs5P-hOK2-TUpZjbT8T__UO6TF-V5LBkPMGFdEiutREdi9xJBcxD3vEYm6Hjm
   1oMUILf2XJ_yA~JWR6M8OpbvUUMEJxDbR2pGEs35uP9_ygOzWKD9w4_EhrpJad-pQYv7n
   BZ-gXf-VBIgN77XX6CcUI0ATJyrpf1Q~sv5CvfTvEW-irkDF0ljDG4La6Hx93H2JWPQaF
   p_zCbFsnA3ZptCfKjplz8vCzGbRpR_YrAU-s5bJVX21YnxucQ~prwqP59i6vWLHTYr2Or
   gZdGt9Ch0dwL8Mqj3aWdCgqdJDEyOlmXEAqlQt7NDqKAsrfYxoHBvIlAsCznM5QeJXQ~v
   rIpF6l8w9uc1IoLKeEZL0p5xrIcChsATKN5NgnVPb9fBV1aXr9On6uoE1Om3t0-uRG7ab
   yZKqWc0XwiGT8G2w~8123q99uFyMwPjkiqm_JjIwwYd2IxDQvR62crSq9QEi77wGqRXmW
   z5ZNDIbQ77oIVh-VhjifJsLcxCwbfaN-Lw

        Figure 7: Issued JWP (SU-ES256, JSON, Compact Serialization)

   To present this JPT, we first use the following presentation header
   with a nonce (provided by the Verifier):

   {
     "alg": "SU-ES256",
     "aud": "https://recipient.example.com",
     "nonce": "nLK_RR7hryKlRfCZgGz9FQ4PZX_IbcL-SMtF30IJQz4"
   }

               Figure 8: Presentation Header (SU-ES256, JSON)

   eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiJuTEtfUlI3aHJ5S2xSZkNaZ0d6OUZRNFBaWF9JYmNMLVNNdEYzME
   lKUXo0In0

     Figure 9: Presentation Header (SU-ES256, JSON, Base64url-Encoded)

   We apply selective disclosure of only the given name and age claims
   (family name and email hidden), and remove the proof components
   corresponding to these entries.





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   Using the selectively disclosed information, we generate the
   presentation internal representation.  Using that and the selectively
   disclosed payloads, we get the following presented JPT in compact
   serialization:

   eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiJuTEtfUlI3aHJ5S2xSZkNaZ0d6OUZRNFBaWF9JYmNMLVNNdEYzME
   lKUXo0In0.eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
   vaXNzdWVyLmV4YW1wbGUiLCJocGEiOiJFUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAi
   LCJmYW1pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb
   3Zlcl8yMSJdLCJpZWsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiJORUYtVG
   Q0M1dzS2oybVZHZmdmeFFzcU45cGE5b3ZmMlJOYzRQWUxLcU1NIiwieSI6IkY2Nl9uYV9
   vUG5yOFVYN1R0aGlBSlJhRW5xbzR3UlJBWHZrM1hKVExPQlEifSwiaHBrIjp7Imt0eSI6
   IkVDIiwiY3J2IjoiUC0yNTYiLCJ4IjoiQ0lqbms4WVRESS1uaWtZWmY4VDZ6Nlo1b0Ewa
   W1mcVBIZnhHVWxXbzU4MCIsInkiOiJEYnMtREkxXzBSS1RWcXdFOUlaUmlDZnZMRjVwVm
   1zT0lwbzh4MXdELWdZIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~
   ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bb
   nl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3
   QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI
   6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ~~.pxjdEgByvXszRLN8nNAzLkD9-23F
   pUcT9PC8GJJ1xofOfkIMEftYmK-6UNhxXytVuLx_tBbSvrEOPG5oy1iYFg~FpdvS_bmS7
   4VGnM1PM8VvS7Y0WwxeHiNrg5VrkIwNn6A2NcWqMitKpcCZ7RGevmU3v9JJryh3LeayDb
   DVTuMvg~4BpHKta_iV-nbs5P-hOK2-TUpZjbT8T__UO6TF-V5LBkPMGFdEiutREdi9xJB
   cxD3vEYm6Hjm1oMUILf2XJ_yA~JWR6M8OpbvUUMEJxDbR2pGEs35uP9_ygOzWKD9w4_Eh
   rpJad-pQYv7nBZ-gXf-VBIgN77XX6CcUI0ATJyrpf1Q~sv5CvfTvEW-irkDF0ljDG4La6
   Hx93H2JWPQaFp_zCbFsnA3ZptCfKjplz8vCzGbRpR_YrAU-s5bJVX21YnxucQ~prwqP59
   i6vWLHTYr2OrgZdGt9Ch0dwL8Mqj3aWdCgqdJDEyOlmXEAqlQt7NDqKAsrfYxoHBvIlAs
   CznM5QeJXQ~N0t2JT74-vL3U8D2RA-dH1n9t_N-kgrMEze0o98ukkmbAjAw0oEDe3Vr3z
   JgZRO_2XAuLlSiIuUplL_7nBwVDQ

   |  Figure: Presentation (SU-ES256, JSON, Compact Serialization)

A.2.  Example CBOR-Serialized Single-Use CPT

   This example is meant to mirror the prior compact serialization,
   using RFC8392 (CWT) and claims from [I-D.maldant-spice-oidc-cwt],
   illustrated using [I-D.ietf-cbor-edn-literals] (EDN).

   To simplify this example, the same information is represented as the
   JPT example above, including the same public and private keys.











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   {          / protected header /
     1: 1,     / alg: "SU-ES256" /
     3: 20,    / typ: "JPT" (20CPA) /
     5: "https://issuer.example",  / iss: "https://issuer.example" /
     6: [      / claims /
       6,      / "iat" /
       4,      / "exp" /
       170,    / "family_name" (I-D.maldant-spice-oidc-cwt TBD1) /
       171,    / "given_name"  (I-D.maldant-spice-oidc-cwt TBD2) /
       179,    / "email"       (I-D.maldant-spice-oidc-cwt TBD10) /
       187,    / "address"     (I-D.maldant-spice-oidc-cwt TBD18) /
       "age_over_21"
     ],
     8: {      / iek /
       1: 2,   / kty : "EC2" /
       -1: 1,  / crv: "P-256" /
       -2: h'34417e4dde375ac2a3da65467e07f142ca8df696bda2f7f644d7383d' +
           h'82caa8c3', / x /
       -3: h'17aebf9dafe83e7afc517ed3b618802516849eaa38c114405ef9375c' +
           h'94cb3814'  / y /
     },
     9: {      / hpk /
       1: 2,   / kty: "EC2" /
       -1: 1,  / crv: "P-256" /
       -2: h'0888e793c6130c8fa78a46197fc4facfa679a00d2299fa8f1dfc4652' +
           h'55a8e7cd', / x /
       -3: h'0dbb3e0c8d7fd1129356ac04f486518827ef2c5e69566b0e229a3cc7' +
           h'5c03fa06'  / y /
     },
     10: -9    / hpa: "ESP256" (I-D.ietf-jose-fully-specified-algorithms TBD-9) /
   }

   |  Figure: Issuer Protected Header (SU-ES256, CBOR)


















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   [ / payloads    /
     / iat         / 171452160,
     / exp         / 171719999,
     / family_name / "Doe",
     / given_name  / "Jay",
     / email       / "jaydoe@example.org",
     / address     / {
       / formatted / 1: "1234 Main St.\nAnytown, CA 12345\nUSA",
       / street    / 2: "1234 Main St.",
       / locality  / 3: "Anytown",
       / region    / 4: "CA",
       / post code / 5: "90210",
       / country   / 6: "USA"
     },
     / age_over_21 / true
   ]

   |  Figure: Issuer Payloads (as CBOR array)

   When signed and serialized, the CPT is represented by the following
   CBOR (in hex):






























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   8358cfa701010314057668747470733a2f2f6973737565722e6578616d706c65
   0687060418aa18ab18b318bb6b6167655f6f7665725f323108a4010220012158
   2034417e4dde375ac2a3da65467e07f142ca8df696bda2f7f644d7383d82caa8
   c322582017aebf9dafe83e7afc517ed3b618802516849eaa38c114405ef9375c
   94cb381409a4010220012158200888e793c6130c8fa78a46197fc4facfa679a0
   0d2299fa8f1dfc465255a8e7cd2258200dbb3e0c8d7fd1129356ac04f4865188
   27ef2c5e69566b0e229a3cc75c03fa060a28871a0a3827001a0a3c3d3f63446f
   65634a6179726a6179646f65406578616d706c652e6f7267a601782331323334
   204d61696e2053742e0a416e79746f776e2c2043412031323334350a55534102
   6d31323334204d61696e2053742e0367416e79746f776e046243410565393032
   31300663555341f5885840b6aa6818eda5f245ea31f26f115b285368d59ca055
   60fe7c2aaf918a226d484621e243219dcddcbd45728fc27293aacb6b354b8dde
   b5bf8e4ec890f598b350575840d8bd67920c8ef08b1f069c64fb6aea23ecc772
   6c470c1214943eb10f1e7513c7f0204952bfe186e240bb7be35f72a81ce57ca2
   895906d0cf353816b3c6b5ca825840a9ac8e08a53108e6cb00b623741ede804f
   c937492bbb6bf934a7fa66ff2a2a925c5ee1bb769df36af4e626ee40940f82a3
   078988eca9fad58c9abc883e9ba64e58408cbc64b0742ef7bf0e4bdd9ab2bd00
   43cc181ac2ea496c3ddf069c27b338122f501d6df13c9b370612c82b64237d4b
   6b80be2b7d7caea69efe0db4c7d6e353d95840f16d662baa168ad898ed65d2b5
   36351aaefd52ab9418a1e141d6eebf3511e42866223d18733f7f483bfd581159
   4a18f51a2a8232a5d4dad738d4bcccde1928105840da9c58f364176f59dd1096
   1cc1036bf4ac74f22b290d327fc45ec00d5834e5dbff6bdff12d140762413d90
   a7d6c2275b69fe918cd8fa12a35c51fe4c1cd9a74d5840ab2d7616abc91f9a58
   e25fb8181e2ac02315163950cfbe0e1e275b06d7634f093267177c0613108503
   1b8574d8b233654f2cf57a50a76e75930cce731b08741d5840826b7c5dbc46b5
   2b6c81fff41c9e356c2685290dd85e7315a39a7d46ceabd6ca75e898ad42ce46
   ff7ff0171ebcf67be71a23b8f5006a9dc03a8155f5ae12ab8b

   |  Fixtures: Issued Form (SU-ES256, CBOR)

   The presented form, similarly to the issued form above, is made with
   the holder conveying the same parameters and the same set of
   selectively disclosed payloads as the JPT above:

   {          / protected header /
     1: 1,    / alg: "SU-ES256" /
     6: "https://recipient.example.com", / aud /
     7: h'9cb2bf451ee1af22a545f099806cfd150e0f657fc86dc2fe48cb45df4209433e', / nonce /
   }

   |  Figure: Holder Protected Header (SU-ES256, CBOR)

   When the appropriate proof is generated, the CPT is serialized into
   the following CBOR (in hex):







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   845846a3010106781d68747470733a2f2f726563697069656e742e6578616d70
   6c652e636f6d0758209cb2bf451ee1af22a545f099806cfd150e0f657fc86dc2
   fe48cb45df4209433e58cfa701010314057668747470733a2f2f697373756572
   2e6578616d706c650687060418aa18ab18b318bb6b6167655f6f7665725f3231
   08a40102200121582034417e4dde375ac2a3da65467e07f142ca8df696bda2f7
   f644d7383d82caa8c322582017aebf9dafe83e7afc517ed3b618802516849eaa
   38c114405ef9375c94cb381409a4010220012158200888e793c6130c8fa78a46
   197fc4facfa679a00d2299fa8f1dfc465255a8e7cd2258200dbb3e0c8d7fd112
   9356ac04f486518827ef2c5e69566b0e229a3cc75c03fa060a28891a0a382700
   1a0a3c3d3f63446f65634a6179726a6179646f65406578616d706c652e6f7267
   a601782331323334204d61696e2053742e0a416e79746f776e2c204341203132
   3334350a555341026d31323334204d61696e2053742e0367416e79746f776e04
   624341056539303231300663555341f5f6f6875840b6aa6818eda5f245ea31f2
   6f115b285368d59ca05560fe7c2aaf918a226d484621e243219dcddcbd45728f
   c27293aacb6b354b8ddeb5bf8e4ec890f598b350575840d8bd67920c8ef08b1f
   069c64fb6aea23ecc7726c470c1214943eb10f1e7513c7f0204952bfe186e240
   bb7be35f72a81ce57ca2895906d0cf353816b3c6b5ca825840a9ac8e08a53108
   e6cb00b623741ede804fc937492bbb6bf934a7fa66ff2a2a925c5ee1bb769df3
   6af4e626ee40940f82a3078988eca9fad58c9abc883e9ba64e58408cbc64b074
   2ef7bf0e4bdd9ab2bd0043cc181ac2ea496c3ddf069c27b338122f501d6df13c
   9b370612c82b64237d4b6b80be2b7d7caea69efe0db4c7d6e353d95840f16d66
   2baa168ad898ed65d2b536351aaefd52ab9418a1e141d6eebf3511e42866223d
   18733f7f483bfd5811594a18f51a2a8232a5d4dad738d4bcccde1928105840da
   9c58f364176f59dd10961cc1036bf4ac74f22b290d327fc45ec00d5834e5dbff
   6bdff12d140762413d90a7d6c2275b69fe918cd8fa12a35c51fe4c1cd9a74d58
   40d3eb13531d9f31afe24cc0067ef534e05cce49e1bb15d1fc3eb84411010cee
   94c04a8ab21a094c07f02cb17e53f536a95df131785310b7effe56a7f11cc8b4
   dc

   |  Figure: Presented Form (SU-ES256, CBOR)

A.3.  Example BBS JWP

   The following example uses the BBS algorithm.

   This is the Issuer's stable private key in the JWK format:















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   {
     "kty": "EC2",
     "alg": "BBS",
     "use": "proof",
     "crv": "BLS12381G2",
     "x": "FSALHintWxAGnDaZQIwO-8KXo2AhfB465h9Q_p2vmW0gfiyRYqXR6OwZJwvbm
          djxCedzqrFRKj7hu6i8opC14UV-7c6aCLywJRC9FIE9O768aYu49LGLQk9pm_C
          ZzGxO",
     "y": "EDwgBDmAIgsXR54fVmLIwgJNB6TglN5nbiJL-CWUMWivaHMadv6QJZ4Mmp0eX
          -v1Ft4tqRplP55QnxACSrpXNR-XvzLx4e9QAP6_kRVt8Idw23DsSpLH7cZCuJt
          xTduv",
     "d": "QeD17OP-QsO2gwre-0Sh67Ocefp-T748CaWnqOfv0e0"
   }

                  Figure 10: BBS private key in JWK format

   There is no additional holder key necessary for presentation proofs.

   For the following protected header and array of payloads:

   {
     "kid": "HjfcpyjuZQ-O8Ye2hQnNbT9RbbnrobptdnExR0DUjU8",
     "alg": "BBS"
   }

                 Figure 11: Example issuer protected header

   These components are signed using the private issuer key previously
   given, which is then representable in the following serialization:

   eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRuRXhSMERValU4I
   iwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~Imph
   eWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b
   3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIi
   wibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTI
   zNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.ocivOQdcgeStlb0wTpLGl6OOpQzGKAUhkC
   pDUBamitb4zbT_gSxFmWbNeQIg1K2RUCuytdPurk1ZXvailT1ghpoB93lkBx9VqK1-hdQ
   Jmuw

          Figure 12: Issued JWP (BBS, JSON, Compact Serialization)

   For a presentation with the following presentation header:

   {
       "alg": "BBS",
       "aud": "https://recipient.example.com",
       "nonce": "wrmBRkKtXjQ"
   }



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                   Figure 13: Holder Presentation Header

   The holder decides to share all information other than the email
   address, and generates a proof.  That proof is represented in the
   following serialization:

   eyJhbGciOiJCQlMiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC5leGFtcGxlLmNvbSIsI
   m5vbmNlIjoid3JtQlJrS3RYalEifQ.eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJ
   UOVJiYm5yb2JwdGRuRXhSMERValU4IiwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxN
   zE5OTk5OQ~IkRvZSI~IkpheSI~~~.qZFqpCVx72l_MlRL_XWALbrcJJNY555AtU4WeEqJ
   -1n_2rI4vIDVW6v6ojuf6s17lb3xypmdxI0ua8_gA75klqMnYYuXhC7QQ_HSiZHSLJ52Y
   7341RlHjJ02TD4QBCwZilv6UsILHA626R9uHca10HeMjteOWksOL97YnkxTfnRX0NO26n
   sQp1nF9-hgJNDxJls2HOcKVZdrmbIxhHhnYFKa6p6rKqxLzkPiZRrD2cchSJ8z9bvkyMz
   gNFCc5tOYyvXjjZgJkO2rgRWj0UnGzW88-PO7f_jAQVQr97F2eU45r8vQrmI_KCUtxq8I
   xi-FFuGZDJ31ZLC4sjXVZJgB_nYNDNuudXR7VgMEbh-YVytqN7DIjUyH2dZfRwb1wikAy
   dX_gpFfRrs0vLBMAKVoriS-Wcr3u60Em0vZ_EQz07Pz7WvHO6oObZVqY_6eEWlpFWiAjE
   QA-dQ-KT8ogcMcXRrN0-RGnIGthr_xB4jTGjg

       Figure 14: Presentation JWP (BBS, JSON, Compact serialization)

A.4.  Example MAC JWP

   The following example uses the MAC-H256 algorithm.

   This is the Issuer's stable private key in the JWK format:

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "a_H-BwPtMTftwSmvcm7IVc4SXVORAZI7-3s1sJadJJc",
     "y": "CDrp08C0zI8Fnu2_02neoC4DCrDdhZWasbK-86luj08",
     "d": "vewf1OM4w1lPXVc8FjfiDEUL-mRdabs1AhUWIcgTqRc"
   }

                       Figure 15: Issuer private key

   This is the Issuer's ephemerally generated shared secret:

   "eHB4gtXM3571_EZkCq7Jtxchd_NOfej5A-3kQTNUWA8"

                          Figure 16: Shared Secret

   This is the Holder's presentation private key in the JWK format:








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   {
     "kty": "EC",
     "crv": "P-256",
     "x": "CIjnk8YTDI-nikYZf8T6z6Z5oA0imfqPHfxGUlWo580",
     "y": "Dbs-DI1_0RKTVqwE9IZRiCfvLF5pVmsOIpo8x1wD-gY",
     "d": "HbSTQhLXQ-UhSSrcINHmZyBFTYUm8jYVv96WRhQkFV4"
   }

                       Figure 17: Holder private key

   For the following protected header and array of payloads:

   {
     "alg": "MAC-H256",
     "hpa": "ES256",
     "typ": "JPT",
     "iss": "https://issuer.example",
     "claims": [
       "iat",
       "exp",
       "family_name",
       "given_name",
       "email",
       "address",
       "age_over_21"
     ],
     "hpk": {
       "kty": "EC",
       "crv": "P-256",
       "use": "sign",
       "x": "CIjnk8YTDI-nikYZf8T6z6Z5oA0imfqPHfxGUlWo580",
       "y": "Dbs-DI1_0RKTVqwE9IZRiCfvLF5pVmsOIpo8x1wD-gY"
     }
   }

                 Figure 18: Example issuer protected header















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   [
       1714521600,
       1717199999,
       "Doe",
       "Jay",
       "jaydoe@example.org",
       {
           "formatted": "1234 Main St.\nAnytown, CA 12345\nUSA",
           "street_address": "1234 Main St.",
           "locality": "Anytown",
           "region": "CA",
           "postal_code": 12345,
           "country": "USA"
       },
       true
   ]

      Figure 19: Example issuer payloads (as members of a JSON array)

   The issuer generates an array of derived keys, one per payload slot.
   This is done using the shared secret as the key and a binary value
   based on the payload slot index (from zero) as input to the HMAC
   operation.

   This results in the following set of derived keys:

   [
     "9FyemYNWikTGveItu5jwtvtANY0GcrFpiQIafsqeHko",
     "yVuV3aSouz_ltZYp0WEI_K2E4D4VST8RxEIRbH546NE",
     "yhsoSM91UsgNyLIi7jqIOIWpo4O6EsujjmTMB6f1Mq4",
     "B9dviMfkDIxQYk--9gC0LlykV0gb8JngqzeLvv6zhBU",
     "9xGHe1gwpPMLZCbkoCgxa53qgK6k6UuIdkDYthHFHQw",
     "2-ZDhjHAjifHFBkffK-QuojeO3jq2dTOf7-s_CsTy_8",
     "_5ltmA2tXYZHoQCS7Ol8Y-Px4ihD_YgzH8pu4oa9fhY"
   ]

            Figure 20: Derived payload keys (Base64url-Encoded)

   A MAC is generated for each payload using the corresponding derived
   payload key.  This results in the following set of MAC values:











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   [
     "-rvi3PUhQjiV1oInXpeHRc1DrqU7Jk9douxFHIg-0GI",
     "944v108bxpSSx4WJAmYpGP5RZHmNOIdTy_K27nzxYaE",
     "3dhW0zUALO4XPcM8nsuq_Rse7dPfxzEq12XMhRcFP6Q",
     "mI9HriPbQCydpgbN4CSYU1-gV-X-_T4fKi0GXv-ODi4",
     "TjfJENJVS1LQNSutIKS_8blbNOaJL_k3Qa5aXCTWk8E",
     "5rzGsqlVqsvhgi1L60joN4Y5OfKnZuyW_i9WTGgv8sk",
     "Jtonk4Bz8BRFsISJXhdwxLNuKhyJ9cOtuRnbticA4t4"
   ]

             Figure 21: Payload MAC values (Base64url-Encoded)

   The issuer protected header and payload MAC values are combined into
   a binary representation known as the Compact MAC Representation.
   This representation is signed with the issuer's private key.

   The proof consists of two octet string values: the signature over the
   combined MAC representation, and the shared secret.

   [
     "k2AL_s8SgbuyEhLpB7mvwMrtNXrXIPv2mryKPWp1jSOf3em6A6ETeOZZPaFgUuCZ8k
   NIq9BYVLD0QE_tk28d8w",
     "u-JxVHu0PUwL19KXLZZihXU6GCrap3mQ1RUJIdujgis"
   ]

                Figure 22: Issued Proof (Base64url-Encoded)

   The final issued JWP in compact serialization is:

   eyJhbGciOiJNQUMtSDI1NiIsImhwYSI6IkVTMjU2IiwidHlwIjoiSlBUIiwiaXNzIjoia
   HR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbH
   lfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJ
   dLCJocGsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsInVzZSI6InNpZ24iLCJ4Ijoi
   Q0lqbms4WVRESS1uaWtZWmY4VDZ6Nlo1b0EwaW1mcVBIZnhHVWxXbzU4MCIsInkiOiJEY
   nMtREkxXzBSS1RWcXdFOUlaUmlDZnZMRjVwVm1zT0lwbzh4MXdELWdZIn19.MTcxNDUyM
   TYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJm
   b3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic
   3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIi
   wicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~
   dHJ1ZQ.k2AL_s8SgbuyEhLpB7mvwMrtNXrXIPv2mryKPWp1jSOf3em6A6ETeOZZPaFgUu
   CZ8kNIq9BYVLD0QE_tk28d8w~u-JxVHu0PUwL19KXLZZihXU6GCrap3mQ1RUJIdujgis

       Figure 23: Issued JWP (MAC-H256, JSON, Compact Serialization)

   Next, we show the presentation of the JWP with selective disclosure.

   For presentation with the following presentation protected header:




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   {
     "alg": "MAC-H256",
     "aud": "https://recipient.example.com",
     "nonce": "nLK_RR7hryKlRfCZgGz9FQ4PZX_IbcL-SMtF30IJQz4"
   }

                  Figure 24: Presentation Protected Header

   The holder will take the issuer proof (including shared secret) and
   derive the same individual payload MAC values (above).

   In this case, the holder has decided not to disclose the last three
   claims provided by the issuer (corresponding to email, address, and
   age_over_21)

   For each payload slot, the holder will provide one of two values as
   part of the proof value.  For a disclosed payload, the holder will
   provide the corresponding derived key.  For a non-disclosed payload,
   the holder will provide the corresponding MAC value.

   The final presented proof value is an array of octet strings.  The
   contents are presentation header signature, followed by the issuer
   signature, then the value disclosed by the holder for each payload.
   This results in the following proof:

   [
     "k2AL_s8SgbuyEhLpB7mvwMrtNXrXIPv2mryKPWp1jSOf3em6A6ETeOZZPaFgUuCZ8k
   NIq9BYVLD0QE_tk28d8w",
     "9FyemYNWikTGveItu5jwtvtANY0GcrFpiQIafsqeHko",
     "yVuV3aSouz_ltZYp0WEI_K2E4D4VST8RxEIRbH546NE",
     "yhsoSM91UsgNyLIi7jqIOIWpo4O6EsujjmTMB6f1Mq4",
     "B9dviMfkDIxQYk--9gC0LlykV0gb8JngqzeLvv6zhBU",
     "TjfJENJVS1LQNSutIKS_8blbNOaJL_k3Qa5aXCTWk8E",
     "5rzGsqlVqsvhgi1L60joN4Y5OfKnZuyW_i9WTGgv8sk",
     "Jtonk4Bz8BRFsISJXhdwxLNuKhyJ9cOtuRnbticA4t4",
     "MxboV_EnKbRhkOSsZjhxfPuisMxpYpuBYffmgk6FzZpmlwq-7yMTxTScRYP_ZgtTQD
   OgxoW8FnHMF8d1ptnbSA"
   ]

             Figure 25: Presentation proof (Base64url-Encoded)

   The final presented JWP in compact serialization is:









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   eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiJuTEtfUlI3aHJ5S2xSZkNaZ0d6OUZRNFBaWF9JYmNMLVNNdEYzME
   lKUXo0In0.eyJhbGciOiJNQUMtSDI1NiIsImhwYSI6IkVTMjU2IiwidHlwIjoiSlBUIiw
   iaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsImNsYWltcyI6WyJpYXQiLCJleHAi
   LCJmYW1pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb
   3Zlcl8yMSJdLCJocGsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsInVzZSI6InNpZ2
   4iLCJ4IjoiQ0lqbms4WVRESS1uaWtZWmY4VDZ6Nlo1b0EwaW1mcVBIZnhHVWxXbzU4MCI
   sInkiOiJEYnMtREkxXzBSS1RWcXdFOUlaUmlDZnZMRjVwVm1zT0lwbzh4MXdELWdZIn19
   .MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.k2AL_s8SgbuyEhLpB7m
   vwMrtNXrXIPv2mryKPWp1jSOf3em6A6ETeOZZPaFgUuCZ8kNIq9BYVLD0QE_tk28d8w~9
   FyemYNWikTGveItu5jwtvtANY0GcrFpiQIafsqeHko~yVuV3aSouz_ltZYp0WEI_K2E4D
   4VST8RxEIRbH546NE~yhsoSM91UsgNyLIi7jqIOIWpo4O6EsujjmTMB6f1Mq4~B9dviMf
   kDIxQYk--9gC0LlykV0gb8JngqzeLvv6zhBU~TjfJENJVS1LQNSutIKS_8blbNOaJL_k3
   Qa5aXCTWk8E~5rzGsqlVqsvhgi1L60joN4Y5OfKnZuyW_i9WTGgv8sk~Jtonk4Bz8BRFs
   ISJXhdwxLNuKhyJ9cOtuRnbticA4t4~MxboV_EnKbRhkOSsZjhxfPuisMxpYpuBYffmgk
   6FzZpmlwq-7yMTxTScRYP_ZgtTQDOgxoW8FnHMF8d1ptnbSA

      Figure 26: Presented JWP (MAC-H256, JSON, Compact Serialization)

Appendix B.  Acknowledgements

   This work was incubated in the DIF Applied Cryptography Working Group
   (https://identity.foundation/working-groups/crypto.html).

   We would like to thank Alberto Solavagione for his valuable
   contributions to this specification.

   The BBS examples were generated using the library at
   https://github.com/mattrglobal/pairing_crypto
   (https://github.com/mattrglobal/pairing_crypto) .

Appendix C.  Document History

   [[ To be removed from the final specification ]]

   -10

   *  Clarify MAC issuance and presentation using new "payload slot"
      nomenclature.
   *  Define a new binary "Presentation Internal Representation" so that
      the holder signature protects the entire presentation
   *  Leverage the new "Holder Presentation Algorithm" to allow the
      holder algorithm to be independent from the signature algorithm
      used by the issuer
   *  Redefine computation of the "Combined MAC Representation" to more
      closely match the new Presentation Internal Representation.
   *  Change the MAC algorithm to directly sign the binary Combined MAC
      Representation rather than convert it to a JWS.



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   *  Do not unnecessarily hash the issuer protected header inside the
      Combined MAC Representation, so that it can provide some manner of
      domain separation.
   *  Clarify how verifiers are to generate the Combined MAC
      Representation from available information.
   *  Provider step-by-step instructions for verification of a
      presentation
   *  Change Proof Key to Issuer Ephemeral Key and Presentation Key to
      Holder Presentation Key

   -09

   *  Remove JSON serialization
   *  Added CBOR (CPT) example to the appendix using SU-ES256

   -08

   *  Made some additional references normative.
   *  Corrected SU-ES256 issuer protected header including private keys

   -07

   *  Changing primary editor
   *  Update registry template for algorithms to account for integer
      CBOR labels
   *  Restylize initial registry entries for readability
   *  Defer BBS key definition to
      [I-D.ietf-cose-bls-key-representations]
   *  Modify example generation to use proof_key and presentation_key
      names
   *  Change proof_jwk to proof_key and presentation_jwk to
      presentation_key to better represent that the key may be JSON or
      CBOR-formatted.
   *  Moved the registry for proof_key and presentation_key to JWP where
      they are defined.  Consolidated usage, purpose, and requirements
      from algorithm usage under these definitions.
   *  Combined BBS-PROOF into BBS

   -06

   *  Update reference to new repository home
   *  Fixed #77: Removed vestigial use of presentation_header.
   *  Correct pjwk to presentation_jwk

   -05

   *  Update of appendix describing MAC-H256 to now also be generated by
      the build system from a common set of code and templates.



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   *  Update single use algorithm to use an array of octet values rather
      than requiring splitting an octet buffer into parts during
      generation of a presentation and during verification.
   *  Update BBS algorithm description and examples to clarify the proof
      is an array with a single octet string.
   *  Update MAC algorithm to use an array of octet values for the
      proof, rather than requiring splitting an octet buffer into parts.
   *  Add new section on the Combined MAC Representation to clarify
      operations are serving to recreate this octet string value.
   *  Correct reference to the latest BBS draft.
   *  SU and MAC families now use raw JWA rather than JWS and
      synthesized headers
   *  Change algorithms to not use base64url-encoding internally.
      Algorithms are meant to operate on octets, while base64url-
      encoding is used to represent those octets in JSON and compact
      serializations.

   -04

   *  Refactoring figures and examples to be built from a common set
      across all three documents
   *  Move single-use example appendix from JWP to JPA
   *  Change algorithm from BBS-DRAFT-5 to BBS, and from BBS-PROOF-
      DRAFT-5 to BBS-PROOF
   *  Update BBS ciphersuite ID to BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_
   *  Update to draft 5 BLS key representations

   -03

   *  Improvements resulting from a full proofreading.
   *  Populated IANA Considerations section.
   *  Updated to use BBS draft -05.
   *  Updated examples.

   -02

   *  Add new BBS-DRAFT-3 and BBS-PROOF-DRAFT-3 algorithms based on
      draft-irtf-cfrg-bbs-signatures-03.
   *  Remove prior BBS-X algorithm based on a particular implementation
      of earlier drafts.

   -01

   *  Correct cross-references within group
   *  Describe issuer_header and presentation_header
   *  Update BBS references to CFRG drafts
   *  Rework reference to HMAC ( RFC2104 )
   *  Remove ZKSnark placeholder



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   -00

   *  Created initial working group draft based on draft-jmiller-jose-
      json-proof-algorithms-01

Authors' Addresses

   Michael B. Jones
   Self-Issued Consulting
   Email: michael_b_jones@hotmail.com
   URI:   https://self-issued.info/


   David Waite
   Ping Identity
   Email: dwaite+jwp@pingidentity.com


   Jeremie Miller
   Ping Identity
   Email: jmiller@pingidentity.com






























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