



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


                         JSON Proof Algorithms
                draft-ietf-jose-json-proof-algorithms-12

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 May 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 Header . . . . . . . . . . . . . . . . . . . .   7
       6.1.6.  Payloads  . . . . . . . . . . . . . . . . . . . . . .   8
       6.1.7.  Proof . . . . . . . . . . . . . . . . . . . . . . . .   8
       6.1.8.  Presentation 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 Header . . . . . . . . . . . . . . . . . . . .  16
       6.4.5.  Issuer Proof  . . . . . . . . . . . . . . . . . . . .  16
       6.4.6.  Presentation 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 . . . . . . . . . . . . . . . . . .  40
   Appendix C.  Document History . . . . . . . . . . . . . . . . . .  41
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  43

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 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 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 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 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 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
   Header that provides replay protection.








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5.4.  Verify

   Performed by the verifier to verify the 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
   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
   Header as well as individual payloads of an Issued JWP.  The issuer
   uses a stable public key to sign each Header, and a per-JWP ephemeral
   key (conveyed within the 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 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 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 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 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 Header signature, with an additional entry
   for each payload signature.

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

   To generate a new presentation, the holder first creates a
   Presentation 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 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 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 Header MUST contain the same Algorithm protected
   header as the Issuer Header.  The Holder Presentation Algorithm
   Header Parameter 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
   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 Presentation Header, Issuer 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 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
       Header octets, using the issuer's stable key.
   3.  Extract the holder presentation key and holder presentation
       algorithm (if present) from the Issuer 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 Header

   3.   0x5B

   4.   The length and octets of the Issuer 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 cipher suite 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 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 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 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
   Header as header, the issuance proof as signature, the issuance
   payloads as messages, and the holder's Presentation 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 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
   Header as header, the issuance proof as signature, the holder's
   Presentation 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 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 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 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 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 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 Header

   See the Presentation 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 Presentation Header, Issuer 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
       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 Header octets, using the issuer's stable key.
   4.  Extract the holder presentation key and holder presentation
       algorithm (if present) from the Issuer 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 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, under the "JSON Object Signing and Encryption (JOSE)"
   registry group.  The registry records values values of the JWP alg
   (algorithm) Header Parameter.  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.






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   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
   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 of 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 IETF Stream 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



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      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
      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



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   *  Algorithm JSON Label: BBS
   *  Algorithm CBOR Label: 4
   *  Algorithm Description: Corresponds to a cipher suite 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-19, 16 October 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cbor-
              edn-literals-19>.

   [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-08, 4 November 2025,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cose-
              bls-key-representations-08>.

   [I-D.ietf-spice-oidc-cwt]
              Maldant, B. and M. B. Jones, "OpenID Connect Standard
              Claims Registration for CBOR Web Tokens", Work in
              Progress, Internet-Draft, draft-ietf-spice-oidc-cwt-02, 20
              October 2025, <https://datatracker.ietf.org/doc/html/
              draft-ietf-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": "MQGKGfEcKSXsHBhBSrDjYxvA6NqBh4X5ylt9rGPVuLg",
     "y": "JVguv8zBJUEsNqMAAlOqX_DigKPY4P3oR-LFCqOAvQ0",
     "d": "wilgoSc8vpMoxz8tJ4roRF9di9l9L4RukWrPT6wdZi8"
   }

                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": "YrcAuI5hLgCRRfIMKeJ9276ld1sJ7oD8l-ctY4zfdEs",
     "y": "JBeTWoj1o2Dbwfw4oXbf1aQcuUzvNhRZbgGoh2uh7-M",
     "d": "0Vhqf4UN-2FQ4uFCxXGuza-8uX7ykM_S0CyUEkD5mDM"
   }

           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": "9f65fOnwQnkAz9Xh0hrDqt_Zs4Fsu-b9woMh0V27JRo",
     "y": "x4Cg8h1q738lrnguGv5XkadWT59tfFytlMO3hVJMe_Q",
     "d": "T0hKcZ1iWLGrRSRzC9WZM3xAso9djnpYVNVeu3nql6A"
   }

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

   The 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": "YrcAuI5hLgCRRfIMKeJ9276ld1sJ7oD8l-ctY4zfdEs",
       "y": "JBeTWoj1o2Dbwfw4oXbf1aQcuUzvNhRZbgGoh2uh7-M"
     },
     "hpk": {
       "kty": "EC",
       "crv": "P-256",
       "x": "9f65fOnwQnkAz9Xh0hrDqt_Zs4Fsu-b9woMh0V27JRo",
       "y": "x4Cg8h1q738lrnguGv5XkadWT59tfFytlMO3hVJMe_Q"
     }
   }

                  Figure 4: Issuer Header (SU-ES256, JSON)

   eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
   mV4YW1wbGUiLCJocGEiOiJFUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbH
   lfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJ
   dLCJpZWsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiJZcmNBdUk1aExnQ1JS
   ZklNS2VKOTI3NmxkMXNKN29EOGwtY3RZNHpmZEVzIiwieSI6IkpCZVRXb2oxbzJEYndmd
   zRvWGJmMWFRY3VVenZOaFJaYmdHb2gydWg3LU0ifSwiaHBrIjp7Imt0eSI6IkVDIiwiY3
   J2IjoiUC0yNTYiLCJ4IjoiOWY2NWZPbndRbmtBejlYaDBockRxdF9aczRGc3UtYjl3b01
   oMFYyN0pSbyIsInkiOiJ4NENnOGgxcTczOGxybmd1R3Y1WGthZFdUNTl0ZkZ5dGxNTzNo
   VkpNZV9RIn19

         Figure 5: Encoded Issuer 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
   Header with the associated alg value.  In this example, the fixed
   Header used for each JWS is the serialized JSON Object
   {"alg":"ES256"}.  This 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
   dLCJpZWsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiJZcmNBdUk1aExnQ1JS
   ZklNS2VKOTI3NmxkMXNKN29EOGwtY3RZNHpmZEVzIiwieSI6IkpCZVRXb2oxbzJEYndmd
   zRvWGJmMWFRY3VVenZOaFJaYmdHb2gydWg3LU0ifSwiaHBrIjp7Imt0eSI6IkVDIiwiY3
   J2IjoiUC0yNTYiLCJ4IjoiOWY2NWZPbndRbmtBejlYaDBockRxdF9aczRGc3UtYjl3b01
   oMFYyN0pSbyIsInkiOiJ4NENnOGgxcTczOGxybmd1R3Y1WGthZFdUNTl0ZkZ5dGxNTzNo
   VkpNZV9RIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZU
   BleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCB
   DQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9j
   YWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsI
   mNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.4W_OybS-VeHlWQLfWJxh2SlA2PWCZLqR7YayOUbD
   QkBtfxDCTaJjqGOr7oJsDNYAZQDOTiLHJv-OFc7ScpAV2Q~qrPb-ak5Qt-oc2Ucz-WX0D
   4MrYDRxPQPIRCZiSe8xriInZYauyQudWAuxXM4LotSTlyD-l8zingfvEA5ad9s6A~irJA
   Qg_EBwdkAGrpcpl8xgybJoVG1CI-UF46_0WkcjwL8rAGkdOu98-iQ6ns5ilgKpH2qPlW_
   fEcwpm9FoBLEg~CzshgACXtFzuixPAXDTNmUyl-pw3NgM4xHeF32A3kLT1PWQLmTthFrI
   NBfVKcN7XisFe5dSTjKO8_cNdI6CG8Q~_RnyKDe5SZg4raS9TUfLyWOrD6HF_hAmq35Zu
   gQlRxCOYbk9mKqj7onE5017rMI7xFKymJa9MKcI6_udGUUHSQ~XJ3f2Rs46ihHlbb2uRQ
   haFrdDiLvd21EnC6LN_KLjMgyIZ-IqunRHAsjwz-zjaSLKz2QJTwqZlVa0MF_47VorQ~J
   Iqu0pEZlrkO2F3XXuGU5FgJPdoORNlM9RDhp5miVjPVfQt2f4u_VYdgyOivVJlMzZuOd5
   G59mhIOEiWKy6t-A~cWPuj_C33X2Zu9xADB1Yu6TpC008OXNP0FHfRcNY1xBb1kxHmOXj
   qNh0Ei4h9VVeEuuuwir7_VDYMM_KhvUpkw

        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": "38c7uOSi9raTnAmXDaFaoWEj9_JQL2nOfhqH7YiCwMo"
   }

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

   eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiIzOGM3dU9TaTlyYVRuQW1YRGFGYW9XRWo5X0pRTDJuT2ZocUg3WW
   lDd01vIn0

     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
   29tIiwibm9uY2UiOiIzOGM3dU9TaTlyYVRuQW1YRGFGYW9XRWo5X0pRTDJuT2ZocUg3WW
   lDd01vIn0.eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
   vaXNzdWVyLmV4YW1wbGUiLCJocGEiOiJFUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAi
   LCJmYW1pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb
   3Zlcl8yMSJdLCJpZWsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiJZcmNBdU
   k1aExnQ1JSZklNS2VKOTI3NmxkMXNKN29EOGwtY3RZNHpmZEVzIiwieSI6IkpCZVRXb2o
   xbzJEYndmdzRvWGJmMWFRY3VVenZOaFJaYmdHb2gydWg3LU0ifSwiaHBrIjp7Imt0eSI6
   IkVDIiwiY3J2IjoiUC0yNTYiLCJ4IjoiOWY2NWZPbndRbmtBejlYaDBockRxdF9aczRGc
   3UtYjl3b01oMFYyN0pSbyIsInkiOiJ4NENnOGgxcTczOGxybmd1R3Y1WGthZFdUNTl0Zk
   Z5dGxNTzNoVkpNZV9RIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~
   ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bb
   nl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3
   QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI
   6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ~~.4W_OybS-VeHlWQLfWJxh2SlA2PWC
   ZLqR7YayOUbDQkBtfxDCTaJjqGOr7oJsDNYAZQDOTiLHJv-OFc7ScpAV2Q~qrPb-ak5Qt
   -oc2Ucz-WX0D4MrYDRxPQPIRCZiSe8xriInZYauyQudWAuxXM4LotSTlyD-l8zingfvEA
   5ad9s6A~irJAQg_EBwdkAGrpcpl8xgybJoVG1CI-UF46_0WkcjwL8rAGkdOu98-iQ6ns5
   ilgKpH2qPlW_fEcwpm9FoBLEg~CzshgACXtFzuixPAXDTNmUyl-pw3NgM4xHeF32A3kLT
   1PWQLmTthFrINBfVKcN7XisFe5dSTjKO8_cNdI6CG8Q~_RnyKDe5SZg4raS9TUfLyWOrD
   6HF_hAmq35ZugQlRxCOYbk9mKqj7onE5017rMI7xFKymJa9MKcI6_udGUUHSQ~XJ3f2Rs
   46ihHlbb2uRQhaFrdDiLvd21EnC6LN_KLjMgyIZ-IqunRHAsjwz-zjaSLKz2QJTwqZlVa
   0MF_47VorQ~hRXfnQlPqGHS_l34OqqonK59sgfv-vVnEZ4GD1ePkflRK5Djvj7FCZ3nbx
   56sk4sIptuoxB7w5RDvUMrA5T78w

   |  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.ietf-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'62b700b88e612e009145f20c29e27ddbbea5775b09ee80fc97e72d63' +
           h'8cdf744b', / x /
       -3: h'2417935a88f5a360dbc1fc38a176dfd5a41cb94cef3614596e01a887' +
           h'6ba1efe3'  / y /
     },
     9: {      / hpk /
       1: 2,   / kty: "EC2" /
       -1: 1,  / crv: "P-256" /
       -2: h'f5feb97ce9f0427900cfd5e1d21ac3aadfd9b3816cbbe6fdc28321d1' +
           h'5dbb251a', / x /
       -3: h'c780a0f21d6aef7f25ae782e1afe5791a7564f9f6d7c5cad94c3b785' +
           h'524c7bf4'  / y /
     },
     10: -9    / hpa: "ESP256" (I-D.ietf-jose-fully-specified-algorithms TBD-9) /
   }

   |  Figure: Issuer 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
   2062b700b88e612e009145f20c29e27ddbbea5775b09ee80fc97e72d638cdf74
   4b2258202417935a88f5a360dbc1fc38a176dfd5a41cb94cef3614596e01a887
   6ba1efe309a401022001215820f5feb97ce9f0427900cfd5e1d21ac3aadfd9b3
   816cbbe6fdc28321d15dbb251a225820c780a0f21d6aef7f25ae782e1afe5791
   a7564f9f6d7c5cad94c3b785524c7bf40a28871a0a3827001a0a3c3d3f63446f
   65634a6179726a6179646f65406578616d706c652e6f7267a601782331323334
   204d61696e2053742e0a416e79746f776e2c2043412031323334350a55534102
   6d31323334204d61696e2053742e0367416e79746f776e046243410565393032
   31300663555341f58858406e24dc48da3942b8a46e629c7fc93b5f99fb083f53
   397944dbed450a7492015421dfe80ece89ffb522152eb1ec4e6c919438fdb611
   9570c19ecc57e38bc5786458409d3fbd702e101be31a47f1607e43fb8baee442
   a2253ad765b2b66ad0a95f92b7c01963c18a27c6d6e7512ead5af3cb4a135ef9
   dccfccc07a8c78dc63300551715840dbe78e6a2f8a82b8883e94056f385976d2
   d6148ac437915b14f63cf8f1f938fa804366f128aba0140ba953652a57562fce
   3f5aac98948cf0e23cf02398e287d958405ebbc7dd8ef2d65226cb1d478fcbf4
   d17f8b2c2d92736831e5e506cdd6550cef52010fa390caa2d60ca4f7928343bd
   987e8e8497ca2455edf785577ba466627d58409b5886130e1c0afe1b769b77fb
   eb4adae24a2e01f94224b06abc273621bea28ee729eeb078599a1c0de670e7d5
   807c9965a0c4e237341e8a84d276295393afdd58408b4c09b85512d12d906964
   3c37f4c6974203424b2463d88ca88fc6fc6f7c636cd4fb01291320146e378f82
   106a8ccdb85dd01911df3c7b159a3e84eb593d13395840cf3bb6a429bd3c1f2e
   99cac777a07293a974675a7fb6ffd3c19a1cc286a128b0f83c46110c9572d42a
   d27790e9e5443bd9cfb988a858d0e5ea42d62182f153305840e89e137a073690
   7897b6e7edcfb79e8d98834e2758ab6529794ae031f13c1000f6487ecb178076
   b2f8478ccd7be16ef1cf9e796ad73714a9aba917aad27d1cb0

   |  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'dfc73bb8e4a2f6b6939c09970da15aa16123f7f2502f69ce7e1a87ed8882c0ca', / nonce /
   }

   |  Figure: Presentation 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
   6c652e636f6d075820dfc73bb8e4a2f6b6939c09970da15aa16123f7f2502f69
   ce7e1a87ed8882c0ca58cfa701010314057668747470733a2f2f697373756572
   2e6578616d706c650687060418aa18ab18b318bb6b6167655f6f7665725f3231
   08a40102200121582062b700b88e612e009145f20c29e27ddbbea5775b09ee80
   fc97e72d638cdf744b2258202417935a88f5a360dbc1fc38a176dfd5a41cb94c
   ef3614596e01a8876ba1efe309a401022001215820f5feb97ce9f0427900cfd5
   e1d21ac3aadfd9b3816cbbe6fdc28321d15dbb251a225820c780a0f21d6aef7f
   25ae782e1afe5791a7564f9f6d7c5cad94c3b785524c7bf40a28891a0a382700
   1a0a3c3d3f63446f65634a6179726a6179646f65406578616d706c652e6f7267
   a601782331323334204d61696e2053742e0a416e79746f776e2c204341203132
   3334350a555341026d31323334204d61696e2053742e0367416e79746f776e04
   624341056539303231300663555341f5f6f68758406e24dc48da3942b8a46e62
   9c7fc93b5f99fb083f53397944dbed450a7492015421dfe80ece89ffb522152e
   b1ec4e6c919438fdb6119570c19ecc57e38bc5786458409d3fbd702e101be31a
   47f1607e43fb8baee442a2253ad765b2b66ad0a95f92b7c01963c18a27c6d6e7
   512ead5af3cb4a135ef9dccfccc07a8c78dc63300551715840dbe78e6a2f8a82
   b8883e94056f385976d2d6148ac437915b14f63cf8f1f938fa804366f128aba0
   140ba953652a57562fce3f5aac98948cf0e23cf02398e287d958405ebbc7dd8e
   f2d65226cb1d478fcbf4d17f8b2c2d92736831e5e506cdd6550cef52010fa390
   caa2d60ca4f7928343bd987e8e8497ca2455edf785577ba466627d58409b5886
   130e1c0afe1b769b77fbeb4adae24a2e01f94224b06abc273621bea28ee729ee
   b078599a1c0de670e7d5807c9965a0c4e237341e8a84d276295393afdd58408b
   4c09b85512d12d9069643c37f4c6974203424b2463d88ca88fc6fc6f7c636cd4
   fb01291320146e378f82106a8ccdb85dd01911df3c7b159a3e84eb593d133958
   40181d1c30ba01716f16a43bf9e7a0bb39deefc4bc427102e06d013f9a274fb0
   de5621efdd7c506d6fff78d0368a4d0b9910727bc6deb9ffec68c152bbf75e6b
   c2

   |  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:

   {
     "kty": "OKP",
     "alg": "BBS",
     "use": "proof",
     "crv": "BLS12381G2",
     "x": "jpHvuKcm9_nBaonJxliIQQdrFqk_PpeHEAvU5-2YR7NNH497WkJxMUOKCmgm5
          _H1CF_kuPXlJTs1ij6HSKj6yLb3zIFZyUVANPOL9Wtk37h_d-dS3_-ZCazulTk
          ag7on",
     "d": "I4pwwzNghZ45PlP3pdKrmFZsWYXQGcLxlnEGdH1pVyY"
   }




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                  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 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.qyPOly0YiFRvcsowHooAJsSz2bTA5AShYK
   enLalfethb5Wp64HphVt4DKzquDYMEEpkkHLULpo0K2t7Z7cS3L0qAFVCLtNff_CaO1uX
   1OTU

          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"
   }

                       Figure 13: 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:











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   eyJhbGciOiJCQlMiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC5leGFtcGxlLmNvbSIsI
   m5vbmNlIjoid3JtQlJrS3RYalEifQ.eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJ
   UOVJiYm5yb2JwdGRuRXhSMERValU4IiwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxN
   zE5OTk5OQ~IkRvZSI~IkpheSI~~~.iu_WTzqcjO4KaW3Fr2N1ahO9Uo7PHnkOf130XFpW
   xEEzyMMl3qKg67rGTHQrLYFdos3E-cjs7IEbOwZYaFNI3ho3kDyDhdIIdukSEoeecDW7c
   f6rhhFFe-L-dX4t_eN0rGI5kvxpLBnT6lEXP4y53TdmghkjBU69QnqnoAIT0OleHszORr
   DWgIPTQtgDerUXSm4E7r3cR8UuS92C1FQy7F9BX_cmuG8qdm3Cyr7nNQgevI7QpMdMp_T
   4tkUKmZzzeTuAdxFV6evO1uhKmT2Dwk6go5orjC14GBB4niIwjG8ItA345t7fDiZ41s1N
   IMAgWmtoQRJbVIsAoKxAKBhL8F2AjBDfssfEMbU6JsyWJesQtdQTcmRVPufMKPIaN6e84
   UZkjkFHyh8yGONdhB4VnhreybqvJjSH5CQDTD59e4n52vaDMT502SojTNcwvoWcPrQ37k
   UE4zifzZ9xxfBmHw4BrWvfrKZdhDs5QFAdjyU

       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": "MQGKGfEcKSXsHBhBSrDjYxvA6NqBh4X5ylt9rGPVuLg",
     "y": "JVguv8zBJUEsNqMAAlOqX_DigKPY4P3oR-LFCqOAvQ0",
     "d": "wilgoSc8vpMoxz8tJ4roRF9di9l9L4RukWrPT6wdZi8"
   }

                       Figure 15: Issuer private key

   This is the Issuer's ephemerally generated shared secret:

   "E-W74PlKrVagSBrrRPztEMlYIGGD9F55PBt-pL1O8D8"

                          Figure 16: Shared Secret

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

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "9f65fOnwQnkAz9Xh0hrDqt_Zs4Fsu-b9woMh0V27JRo",
     "y": "x4Cg8h1q738lrnguGv5XkadWT59tfFytlMO3hVJMe_Q",
     "d": "T0hKcZ1iWLGrRSRzC9WZM3xAso9djnpYVNVeu3nql6A"
   }

                       Figure 17: Holder private key




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   For the following 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": "9f65fOnwQnkAz9Xh0hrDqt_Zs4Fsu-b9woMh0V27JRo",
       "y": "x4Cg8h1q738lrnguGv5XkadWT59tfFytlMO3hVJMe_Q"
     }
   }

                      Figure 18: Example Issuer Header

   [
       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)






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   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:

   [
     "jHGnbygUYI5VdO_7DvLq0WRTNSW_uhOax1Y17IUlRAw",
     "0GAdidOeuJ5MgpdMnIagOfa6XfM3Z0NxPtl0x_feV-M",
     "4Jkdr6wXRTc2Q0Ghp8a1Ry4FXIcRqp2Q--3AJW3lCi8",
     "E8zCUoLg7eSsm94sl0D6ND_21mWhQz-BCQ0vmLBruyw",
     "pYGZoTKwJuCt-eihevdercNP9wF6mu4m8DkaIi-9BKc",
     "5tZsuRtnjbZRh2NkwbWNteMfTzm0bm---PhaANFhoi4",
     "2M0w4mF_gUeEQad1h35cervDxeVqniL9r3z0wI8tC04"
   ]

            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:

   [
     "eDQzGY_TspeKEiFFBYGlzRoPbkg7f62uHvzrBuNdbUQ",
     "yn9iTOJPLqzAPzAMnfWFKLJp76aYg0kPpqAWNzoD5WA",
     "Og-TwlajwiV1zaYttoTq8yAEK_km-TJQkC8FcortoUg",
     "wKFQhIyjXu5Rk9kmV4VrqkdYfAN0oj-cWvzFgZyuvLo",
     "i3Ef-YD065WKUg6pPA3AKR0tJasGOvI_1NTCfHvyclM",
     "qcAhk83ldqom114iktYR9UTSvsecFsCU0q8a-fdnxDU",
     "WxLURctRhf1z5BRtRDD8GHcGlQvJA6RjttDKJox4koo"
   ]

             Figure 21: Payload MAC values (Base64url-Encoded)

   The Issuer 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.

   [
     "iPvaOPSOUvKrAmDgK1HrgnV889JuSgte_q_Klcq2ltdYAQ53ENjSWbv1eNTopP17D_
   Xf2uCW3HWRYELDG4Vl_w",
     "0GvOqgngJ0zsuJWl4NV20mbFxVkzJbfxoRPFqRNLqFQ"
   ]

                Figure 22: Issued Proof (Base64url-Encoded)



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   The final issued JWP in compact serialization is:

   eyJhbGciOiJNQUMtSDI1NiIsImhwYSI6IkVTMjU2IiwidHlwIjoiSlBUIiwiaXNzIjoia
   HR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbH
   lfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJ
   dLCJocGsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsInVzZSI6InNpZ24iLCJ4Ijoi
   OWY2NWZPbndRbmtBejlYaDBockRxdF9aczRGc3UtYjl3b01oMFYyN0pSbyIsInkiOiJ4N
   ENnOGgxcTczOGxybmd1R3Y1WGthZFdUNTl0ZkZ5dGxNTzNoVkpNZV9RIn19.MTcxNDUyM
   TYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJm
   b3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic
   3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIi
   wicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~
   dHJ1ZQ.iPvaOPSOUvKrAmDgK1HrgnV889JuSgte_q_Klcq2ltdYAQ53ENjSWbv1eNTopP
   17D_Xf2uCW3HWRYELDG4Vl_w~0GvOqgngJ0zsuJWl4NV20mbFxVkzJbfxoRPFqRNLqFQ

       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 Header:

   {
     "alg": "MAC-H256",
     "aud": "https://recipient.example.com",
     "nonce": "38c7uOSi9raTnAmXDaFaoWEj9_JQL2nOfhqH7YiCwMo"
   }

                       Figure 24: Presentation 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:






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   [
     "iPvaOPSOUvKrAmDgK1HrgnV889JuSgte_q_Klcq2ltdYAQ53ENjSWbv1eNTopP17D_
   Xf2uCW3HWRYELDG4Vl_w",
     "jHGnbygUYI5VdO_7DvLq0WRTNSW_uhOax1Y17IUlRAw",
     "0GAdidOeuJ5MgpdMnIagOfa6XfM3Z0NxPtl0x_feV-M",
     "4Jkdr6wXRTc2Q0Ghp8a1Ry4FXIcRqp2Q--3AJW3lCi8",
     "E8zCUoLg7eSsm94sl0D6ND_21mWhQz-BCQ0vmLBruyw",
     "i3Ef-YD065WKUg6pPA3AKR0tJasGOvI_1NTCfHvyclM",
     "qcAhk83ldqom114iktYR9UTSvsecFsCU0q8a-fdnxDU",
     "WxLURctRhf1z5BRtRDD8GHcGlQvJA6RjttDKJox4koo",
     "ffaMuu14qyIJT-aew2gDLwmjk5RrLR7wU9ekJ-nmAnOrC6gQWJWzpMcUWj1sIVn97l
   ycCDAnFWVo7LUc3qqCOw"
   ]

             Figure 25: Presentation proof (Base64url-Encoded)

   The final presented JWP in compact serialization is:

   eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiIzOGM3dU9TaTlyYVRuQW1YRGFGYW9XRWo5X0pRTDJuT2ZocUg3WW
   lDd01vIn0.eyJhbGciOiJNQUMtSDI1NiIsImhwYSI6IkVTMjU2IiwidHlwIjoiSlBUIiw
   iaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsImNsYWltcyI6WyJpYXQiLCJleHAi
   LCJmYW1pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb
   3Zlcl8yMSJdLCJocGsiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsInVzZSI6InNpZ2
   4iLCJ4IjoiOWY2NWZPbndRbmtBejlYaDBockRxdF9aczRGc3UtYjl3b01oMFYyN0pSbyI
   sInkiOiJ4NENnOGgxcTczOGxybmd1R3Y1WGthZFdUNTl0ZkZ5dGxNTzNoVkpNZV9RIn19
   .MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.iPvaOPSOUvKrAmDgK1H
   rgnV889JuSgte_q_Klcq2ltdYAQ53ENjSWbv1eNTopP17D_Xf2uCW3HWRYELDG4Vl_w~j
   HGnbygUYI5VdO_7DvLq0WRTNSW_uhOax1Y17IUlRAw~0GAdidOeuJ5MgpdMnIagOfa6Xf
   M3Z0NxPtl0x_feV-M~4Jkdr6wXRTc2Q0Ghp8a1Ry4FXIcRqp2Q--3AJW3lCi8~E8zCUoL
   g7eSsm94sl0D6ND_21mWhQz-BCQ0vmLBruyw~i3Ef-YD065WKUg6pPA3AKR0tJasGOvI_
   1NTCfHvyclM~qcAhk83ldqom114iktYR9UTSvsecFsCU0q8a-fdnxDU~WxLURctRhf1z5
   BRtRDD8GHcGlQvJA6RjttDKJox4koo~ffaMuu14qyIJT-aew2gDLwmjk5RrLR7wU9ekJ-
   nmAnOrC6gQWJWzpMcUWj1sIVn97lycCDAnFWVo7LUc3qqCOw

      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) .



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Appendix C.  Document History

   [[ To be removed from the final specification ]]

   -12

   *  IANA Considerations section changes from IANA Early Review
   *  Updated BLS keys to match BLS Key Representations draft 8

   -11

   *  Change Issuer Protected Header to Issuer Header
   *  Change Presentation Protected Header and Holder Presentation
      Header to Presentation Header

   -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.
   *  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




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   -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.
   *  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





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   *  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

   -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





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   Jeremie Miller
   Ping Identity
   Email: jmiller@pingidentity.com
















































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