Skip to main content

JSON Proof Algorithms
draft-ietf-jose-json-proof-algorithms-07

Document Type Active Internet-Draft (jose WG)
Authors Michael B. Jones , David Waite , Jeremie Miller
Last updated 2024-10-21
Replaces draft-jmiller-jose-json-proof-algorithms
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status (None)
Formats
Additional resources Mailing list discussion
Stream WG state WG Document
Document shepherd (None)
IESG IESG state I-D Exists
Consensus boilerplate Unknown
Telechat date (None)
Responsible AD (None)
Send notices to (None)
draft-ietf-jose-json-proof-algorithms-07
jose                                                            M. Jones
Internet-Draft                                    Self-Issued Consulting
Intended status: Standards Track                                D. Waite
Expires: 24 April 2025                                         J. Miller
                                                           Ping Identity
                                                         21 October 2024

                         JSON Proof Algorithms
                draft-ietf-jose-json-proof-algorithms-07

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 24 April 2025.

Copyright Notice

   Copyright (c) 2024 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.

Jones, et al.             Expires 24 April 2025                 [Page 1]
Internet-Draft            json-proof-algorithms             October 2024

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   5.  Algorithm Basics  . . . . . . . . . . . . . . . . . . . . . .   4
     5.1.  Issue . . . . . . . . . . . . . . . . . . . . . . . . . .   4
     5.2.  Confirm . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.3.  Present . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.4.  Verify  . . . . . . . . . . . . . . . . . . . . . . . . .   5
   6.  Algorithm Specifications  . . . . . . . . . . . . . . . . . .   6
     6.1.  Single Use  . . . . . . . . . . . . . . . . . . . . . . .   6
       6.1.1.  JWS Algorithm . . . . . . . . . . . . . . . . . . . .   6
       6.1.2.  Holder Setup  . . . . . . . . . . . . . . . . . . . .   6
       6.1.3.  Issuer Setup  . . . . . . . . . . . . . . . . . . . .   7
       6.1.4.  Signing payloads  . . . . . . . . . . . . . . . . . .   7
       6.1.5.  Issuer Protected Header . . . . . . . . . . . . . . .   7
       6.1.6.  Payloads  . . . . . . . . . . . . . . . . . . . . . .   7
       6.1.7.  Proof . . . . . . . . . . . . . . . . . . . . . . . .   7
       6.1.8.  Presentation Protected Header . . . . . . . . . . . .   7
       6.1.9.  Presentation  . . . . . . . . . . . . . . . . . . . .   8
       6.1.10. Verification  . . . . . . . . . . . . . . . . . . . .   9
       6.1.11. JPA Registration  . . . . . . . . . . . . . . . . . .   9
     6.2.  BBS . . . . . . . . . . . . . . . . . . . . . . . . . . .   9
       6.2.1.  JPA Algorithms  . . . . . . . . . . . . . . . . . . .   9
       6.2.2.  Key Format  . . . . . . . . . . . . . . . . . . . . .   9
       6.2.3.  Issuance  . . . . . . . . . . . . . . . . . . . . . .  10
       6.2.4.  Issuance Proof Verification . . . . . . . . . . . . .  10
       6.2.5.  Presentation  . . . . . . . . . . . . . . . . . . . .  10
       6.2.6.  Presentation Verification . . . . . . . . . . . . . .  11
     6.3.  Message Authentication Code . . . . . . . . . . . . . . .  11
       6.3.1.  Holder Setup  . . . . . . . . . . . . . . . . . . . .  11
       6.3.2.  Issuer Setup  . . . . . . . . . . . . . . . . . . . .  12
       6.3.3.  Combined MAC Representation . . . . . . . . . . . . .  12
       6.3.4.  Issuer Proof  . . . . . . . . . . . . . . . . . . . .  12
       6.3.5.  Presentation Protected Header . . . . . . . . . . . .  13
       6.3.6.  Presentation Proof  . . . . . . . . . . . . . . . . .  13
       6.3.7.  Verification of the Presentation Proof  . . . . . . .  13
       6.3.8.  JPA Registration  . . . . . . . . . . . . . . . . . .  14
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     8.1.  JSON Web Proof Algorithms Registry  . . . . . . . . . . .  15
       8.1.1.  Registration Template . . . . . . . . . . . . . . . .  16
       8.1.2.  Initial Registry Contents . . . . . . . . . . . . . .  17
         8.1.2.1.  Single-Use JWP using ES256 Algorithm  . . . . . .  17
         8.1.2.2.  Single-Use JWP using ES384 Algorithm  . . . . . .  17
         8.1.2.3.  Single-Use JWP using ES512 Algorithm  . . . . . .  17

Jones, et al.             Expires 24 April 2025                 [Page 2]
Internet-Draft            json-proof-algorithms             October 2024

         8.1.2.4.  BBS using SHA-256 Algorithm . . . . . . . . . . .  18
         8.1.2.5.  MAC-H256 Algorithm  . . . . . . . . . . . . . . .  18
         8.1.2.6.  MAC-H384 Algorithm  . . . . . . . . . . . . . . .  18
         8.1.2.7.  MAC-H512 Algorithm  . . . . . . . . . . . . . . .  18
         8.1.2.8.  MAC-K25519 Algorithm  . . . . . . . . . . . . . .  19
         8.1.2.9.  MAC-K448 Algorithm  . . . . . . . . . . . . . . .  19
         8.1.2.10. MAC-H256K Algorithm . . . . . . . . . . . . . . .  19
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  20
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  20
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  20
   Appendix A.  Example JWPs . . . . . . . . . . . . . . . . . . . .  21
     A.1.  Example Single-Use JWP  . . . . . . . . . . . . . . . . .  21
     A.2.  Example BBS JWP . . . . . . . . . . . . . . . . . . . . .  29
     A.3.  Example MAC JWP . . . . . . . . . . . . . . . . . . . . .  32
   Appendix B.  Acknowledgements . . . . . . . . . . . . . . . . . .  39
   Appendix C.  Document History . . . . . . . . . . . . . . . . . .  39
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  41

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.

   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.

Jones, et al.             Expires 24 April 2025                 [Page 3]
Internet-Draft            json-proof-algorithms             October 2024

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.
   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.
   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).

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.

Jones, et al.             Expires 24 April 2025                 [Page 4]
Internet-Draft            json-proof-algorithms             October 2024

   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.

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.

Jones, et al.             Expires 24 April 2025                 [Page 5]
Internet-Draft            json-proof-algorithms             October 2024

   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 is based on using multiple signatures to
   cover the individual payloads, all of which are generated with the
   same Asymmetric JSON Web Algorithm (JWA).  The internal signing
   algorithm to use is part of the registration for a new Single Use
   algorithm identifier.

   The chosen JWA MUST be an asymmetric signing algorithm so that each
   signature can be verified without sharing any private values between
   the parties.  This ensures that the verifier cannot brute force any
   non-disclosed payloads based only on their disclosed individual
   signatures.

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 Presentation Key during the issuance
   and the presentation of every Single Use JWP.  This Presentation Key
   MUST be generated and used for only one JWP.

Jones, et al.             Expires 24 April 2025                 [Page 6]
Internet-Draft            json-proof-algorithms             October 2024

   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.

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 in the issuer protected
   header via the Proof Key header parameter.

   The holder's Presentation Key MUST be included in issuer protected
   header via the Presentation Key header parameter.

   The issuer protected header is signed using the given JWA and 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

   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.

Jones, et al.             Expires 24 April 2025                 [Page 7]
Internet-Draft            json-proof-algorithms             October 2024

   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.

6.1.9.  Presentation

   |  Editor's Note: The current definition here is incomplete, the
   |  holder's signature needs to also incorporate the presented proof.

   The holder derives a new proof as part of presentation.  The
   presented proof value will always contain the issuer's Stable Key
   signature for the issuer protected header as the first element.

   The second element of the presented proof is the holder's signature
   of the presentation protected header using the holder's presentation
   key.  This signature is constructed using the same algorithm
   described in generating the issuer's signature over the issuer
   protected header.  Signing only the presentation header with the
   Presentation Key is sufficient to protect the entire presentation
   since that key is private to the holder and only the contents of the
   presentation header are used for replay prevention.

   For each payload which is to be disclosed, the corresponding payload
   signature (from the issued JWP) is included in the proof.  If a
   payload is omitted from the presented JWP, the signature value will
   NOT be includeed, and the presentation proof will have one less part.

   For example, if the second and fifth of five payloads are not
   disclosed, then the holder's derived proof would consist of the
   issuer's signature over the issuer protected header, the holder's
   signature over the holder's protected header, the ephemeral key
   signature over the first, third and fourth payloads.

   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.

Jones, et al.             Expires 24 April 2025                 [Page 8]
Internet-Draft            json-proof-algorithms             October 2024

6.1.10.  Verification

   The verifier MUST verify the issuer protected header octets against
   the first part in the proof using the issuer's Stable Key. It MUST
   also verify the presentation protected header octets against the
   second part in the proof value using the holder's Presentation Key,
   as provided in the Presentation Key header parameter.

   With the headers verified, the Proof Key header parameter can then be
   used to verify each of the disclosed payload signatures.

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.  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.

6.2.1.  JPA Algorithms

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

6.2.2.  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.

Jones, et al.             Expires 24 April 2025                 [Page 9]
Internet-Draft            json-proof-algorithms             October 2024

6.2.3.  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 and payloads as the octets header and the octets array
   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.

6.2.4.  Issuance Proof Verification

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

   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.

6.2.5.  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.

   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 JSON
   serialization and a zero-length string in compact serialization.

Jones, et al.             Expires 24 April 2025                [Page 10]
Internet-Draft            json-proof-algorithms             October 2024

6.2.6.  Presentation Verification

   Verification of a presentation is done by the verifier using the
   ProofVerify operation from 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.

6.3.  Message Authentication Code

   The Message Authentication Code (MAC) JPA uses a MAC to both generate
   ephemeral keys and compute authentication codes to protect the issuer
   header and each payload individually.

   Like the 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.

   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.

6.3.1.  Holder Setup

   Prior to the issuer creating a new JWP, the issuer MUST have a
   presentation public key provided by the holder.

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

Jones, et al.             Expires 24 April 2025                [Page 11]
Internet-Draft            json-proof-algorithms             October 2024

6.3.2.  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 to 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.

6.3.3.  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 issuer protected header is included in this value as a MAC
   created using the fixed key "issuer_header" in UTF-8 encoded octets.
   The value is the issuer header JSON as a UTF-8 encoded octet string.

   A unique key is generated for each payload using a MAC, with the
   Shared Secret as the key and a value of "payload_X" as UTF-8 encoded
   octets, where "X" is replaced by the zero-based array index of the
   payload, for example "payload_0", "payload_1", etc.

   Each payload then itself has a corresponding MAC, using the above
   per-payload key and the payload octet string.

   The combined MAC representation is the octet string formed by the the
   concatentation of the issuer protected header MAC output, along with
   each payload MAC output.

6.3.4.  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 JWS using its stable public
   key, and a fixed header containing the alg associated with signing
   algorithm in use.

   jws_header = '{"alg":"ES256"}'

Jones, et al.             Expires 24 April 2025                [Page 12]
Internet-Draft            json-proof-algorithms             October 2024

   The signature value of the JWS is extracted and base64url-decoded
   into an octet string.

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

6.3.5.  Presentation Protected Header

   See the JWS Presentation Protected Header (#presentation-protected-
   header) section.

6.3.6.  Presentation Proof

   |  Editor's Note: The current definition here is incomplete, the
   |  holder's signature needs to also incorporate the presented proof.

   The first value in the presentation proof is the presentation
   signature.  This is a signature over the presentation protected
   header, using the key specified by the Presentation Key header
   parameter in the issuer protected header.

   The second value is the issuer signature over the Combined MAC
   Representation provided with the issued form.

   The remaining values are used by the verifier to reconstruct the
   combined MAC representation without access to the Shared Secret.
   There is one value corresponding to each payload, whether it has been
   disclosed or not.

   If a payload is disclosed, the unique per-payload key derived from
   the shared secret is used as the payload's entry in the proof array.

   If a payload is not disclosed, the payload's MAC in the combined MAC
   representation is used as the payload's entry in the proof array.

6.3.7.  Verification of the Presentation Proof

   The verifier must recreate the Combined MAC Representation from the
   presentation proof to verify integrity over the disclosed
   information.

   The issuer protected header MAC is recreated using the same mechanism
   described above.

   For each payload in the presentation:

Jones, et al.             Expires 24 April 2025                [Page 13]
Internet-Draft            json-proof-algorithms             October 2024

   *  If the payload is disclosed, then the presentation proof contains
      the unique per-payload key.  The corresponding payload MAC can be
      computed by performing the MAC operation with this key and the
      corresponding payload.

   *  If the payload is not disclosed, then the presentation proof
      contains the payload MAC, which can be used directly

   The concatenation of the octets of the issuer protected header MAC
   and each payload MAC forms the Combined MAC Representation.  The
   issuer signature in the proof is then verified by converting these
   values to a JWS as described above, and verifying that JWS.

6.3.8.  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
   mailing list, on the advice of one or more Designated Experts.

Jones, et al.             Expires 24 April 2025                [Page 14]
Internet-Draft            json-proof-algorithms             October 2024

   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.
   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 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

Jones, et al.             Expires 24 April 2025                [Page 15]
Internet-Draft            json-proof-algorithms             October 2024

   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
   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.

Jones, et al.             Expires 24 April 2025                [Page 16]
Internet-Draft            json-proof-algorithms             October 2024

   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
      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

Jones, et al.             Expires 24 April 2025                [Page 17]
Internet-Draft            json-proof-algorithms             October 2024

   *  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
   *  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 6.2.1 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 6.3.8 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 6.3.8 of this specification
   *  Algorithm Analysis Documents(s): n/a

8.1.2.7.  MAC-H512 Algorithm

   *  Algorithm Name: MAC-H512

Jones, et al.             Expires 24 April 2025                [Page 18]
Internet-Draft            json-proof-algorithms             October 2024

   *  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 6.3.8 of this specification
   *  Algorithm Analysis Documents(s): n/a

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 6.3.8 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 6.3.8 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 6.3.8 of this specification
   *  Algorithm Analysis Documents(s): n/a

Jones, et al.             Expires 24 April 2025                [Page 19]
Internet-Draft            json-proof-algorithms             October 2024

9.  References

9.1.  Normative References

   [I-D.ietf-jose-json-web-proof]
              Miller, J., Waite, D., and M. B. Jones, "JSON Web Proof",
              Work in Progress, Internet-Draft, draft-ietf-jose-json-
              web-proof-06, 16 September 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-jose-
              json-web-proof-06>.

   [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-07, 23 September 2024,
              <https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-
              bbs-signatures-07>.

9.2.  Informative References

   [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-05, 17 March 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-cose-
              bls-key-representations-05>.

   [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>.

   [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>.

   [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>.

   [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>.

Jones, et al.             Expires 24 April 2025                [Page 20]
Internet-Draft            json-proof-algorithms             October 2024

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

   [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>.

   [VC-DATA-MODEL-2.0]
              Sporny, M., Jr, T. T., Herman, I., Jones, M. B., and G.
              Cohen, "Verifiable Credentials Data Model 2.0", 27
              December 2023, <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 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": "rljcEFI0caNXx29jNkyLXtbPti5qHkokC6PWy9XYAeM",
     "y": "I6OlSc34yeKQMvXvq4aV6M12ESAK9RkdArMIeAWi70M",
     "d": "xa0e8RpopMldqZCT7g9-2gDlWM1PrHz1N-qoQOcXU6U"
   }

                    Figure 1: Issuer Private Key (es256)

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

Jones, et al.             Expires 24 April 2025                [Page 21]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "UUITdYuYGDeP97Tkk08qfRbGuhoR3LemQCRrWzlS-Do",
     "y": "IJxVmTxCIVeNyCmk6sH8CeO7zRrJ1k6HQEPSXKY6H3c",
     "d": "et_fHv5CfgzYakpzHibmX2U75oI_JxEpBSvzc5PoDPQ"
   }

               Figure 2: Issuer Ephemeral Private Key (es256)

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

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "y9wnI7zYYrkcXpd5j9O3qiRDMxmhPdNfbPzHtLIL_H0",
     "y": "A2AJXiAYrlSGfwONgffXWaNnTXx-MXISPFRiwXMpEkg",
     "d": "ZJco2u6h3y4g7M5otiVhTbfAEUSDMTkiSk76URi045c"
   }

                 Figure 3: Holder Presentation Private Key

   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.

Jones, et al.             Expires 24 April 2025                [Page 22]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "alg": "SU-ES256",
     "typ": "JPT",
     "iss": "https://issuer.example",
     "claims": [
       "iat",
       "exp",
       "family_name",
       "given_name",
       "email",
       "address",
       "age_over_21"
     ],
     "proof_key": {
       "kty": "EC",
       "crv": "P-256",
       "x": "UUITdYuYGDeP97Tkk08qfRbGuhoR3LemQCRrWzlS-Do",
       "y": "IJxVmTxCIVeNyCmk6sH8CeO7zRrJ1k6HQEPSXKY6H3c",
       "d": "et_fHv5CfgzYakpzHibmX2U75oI_JxEpBSvzc5PoDPQ"
     },
     "presentation_key": {
       "kty": "EC",
       "crv": "P-256",
       "x": "y9wnI7zYYrkcXpd5j9O3qiRDMxmhPdNfbPzHtLIL_H0",
       "y": "A2AJXiAYrlSGfwONgffXWaNnTXx-MXISPFRiwXMpEkg",
       "d": "ZJco2u6h3y4g7M5otiVhTbfAEUSDMTkiSk76URi045c"
     }
   }

                 Figure 4: Issuer Protected header (es256)

   The JWP Protected Header JSON is serialized (without the above
   whitespace added for readability) and uses UTF-8 encoding to convert
   into an octet string.  This gives:

   eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
   mV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUiLCJnaXZlbl
   9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJvb2Zfa2V5Ijp
   7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ4IjoiVVVJVGRZdVlHRGVQOTdUa2swOHFm
   UmJHdWhvUjNMZW1RQ1JyV3psUy1EbyIsInkiOiJJSnhWbVR4Q0lWZU55Q21rNnNIOENlT
   zd6UnJKMWs2SFFFUFNYS1k2SDNjIiwiZCI6ImV0X2ZIdjVDZmd6WWFrcHpIaWJtWDJVNz
   VvSV9KeEVwQlN2emM1UG9EUFEifSwicHJlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyI
   sImNydiI6IlAtMjU2IiwieCI6Ink5d25JN3pZWXJrY1hwZDVqOU8zcWlSRE14bWhQZE5m
   YlB6SHRMSUxfSDAiLCJ5IjoiQTJBSlhpQVlybFNHZndPTmdmZlhXYU5uVFh4LU1YSVNQR
   lJpd1hNcEVrZyIsImQiOiJaSmNvMnU2aDN5NGc3TTVvdGlWaFRiZkFFVVNETVRraVNrNz
   ZVUmkwNDVjIn19

    Figure 5: Encoded Issuer Protected Header (es256, base64url-encoded)

Jones, et al.             Expires 24 April 2025                [Page 23]
Internet-Draft            json-proof-algorithms             October 2024

   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.

   The resulting JSON serialized JPT using the above examples is:

Jones, et al.             Expires 24 April 2025                [Page 24]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "issuer": "eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
          Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaW
          x5X25hbWUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292
          ZXJfMjEiXSwicHJvb2Zfa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLC
          J4IjoiVVVJVGRZdVlHRGVQOTdUa2swOHFmUmJHdWhvUjNMZW1RQ1JyV3psUy1E
          byIsInkiOiJJSnhWbVR4Q0lWZU55Q21rNnNIOENlTzd6UnJKMWs2SFFFUFNYS1
          k2SDNjIiwiZCI6ImV0X2ZIdjVDZmd6WWFrcHpIaWJtWDJVNzVvSV9KeEVwQlN2
          emM1UG9EUFEifSwicHJlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydi
          I6IlAtMjU2IiwieCI6Ink5d25JN3pZWXJrY1hwZDVqOU8zcWlSRE14bWhQZE5m
          YlB6SHRMSUxfSDAiLCJ5IjoiQTJBSlhpQVlybFNHZndPTmdmZlhXYU5uVFh4LU
          1YSVNQRlJpd1hNcEVrZyIsImQiOiJaSmNvMnU2aDN5NGc3TTVvdGlWaFRiZkFF
          VVNETVRraVNrNzZVUmkwNDVjIn19",
     "payloads": [
       "MTcxNDUyMTYwMA",
       "MTcxNzE5OTk5OQ",
       "IkRvZSI",
       "IkpheSI",
       "ImpheWRvZUBleGFtcGxlLm9yZyI",
       "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
          VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
          kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
          ImNvdW50cnkiOiJVU0EifQ",
       "dHJ1ZQ"
     ],
     "proof": [
       "37RhnitI5rt3skZ9oRDpeGyxSynhvPxbhxe2_NDm4tQ8audwHH4nV7Qt7wN_vfNv
          HZ_P3gkiNdrElSMBZcu1Xg",
       "IIpR1uezrjhTgnVU4LY5KIdZOjayjRHFP6-ULHDv2ctMVSFTprkTpjvUwkgk1T2v
          q6IHO5ptkISaglrWLur8vQ",
       "sBFFXFVZKVuIoB2SiuyDCBSnC6Zkk10nWfsOn-I1CKAI0NC2QBxloc7gzxG4m4EN
          SMKKpa9FKvyOtoBZi4YK2Q",
       "svvidNTTnZU7D5Kze_SKBRhN3vJiUzs1bPQlK8_PIhqQrFhpKRiOI89Qqz6zqGdi
          a1s8IfMYwNPoYJYIlYeNlw",
       "yecfskC44VxcKWgZvUTWOXtp4EZ3kVYKAq1f_vCdPsxRkOrEsx7ADTXQtB0ksDhu
          sEbwrqNP8ouNMSaHtKNucw",
       "nMQ5lVAojfiJhzYYdKvL7kW35gXuquxrwAwntdjoNzfn7h6do63seUuSx8FUckdK
          pDGODhWSCQtM6S38oc4Rcw",
       "VXbFtQwnhCRB0jxdVQe1YDahf2fXAsiIvErjzTGbVFw_T_sjN2GZ9uLAyjzyjjXW
          RwBWpZVs8-evVrvWbnPoBA",
       "TP3ATOtrSCGq1Ej_aLMEkFvgnlacq4S5Kx0an3_45jNE9ZrAg9Dvm2hEtRQwYF_u
          EBIL17atsb2jo7y6tLthVQ"
     ]
   }

             Figure 6: Issued JWP in JSON Serialization (es256)

   The compact serialization of the same JPT is:

Jones, et al.             Expires 24 April 2025                [Page 25]
Internet-Draft            json-proof-algorithms             October 2024

   eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
   mV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUiLCJnaXZlbl
   9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJvb2Zfa2V5Ijp
   7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ4IjoiVVVJVGRZdVlHRGVQOTdUa2swOHFm
   UmJHdWhvUjNMZW1RQ1JyV3psUy1EbyIsInkiOiJJSnhWbVR4Q0lWZU55Q21rNnNIOENlT
   zd6UnJKMWs2SFFFUFNYS1k2SDNjIiwiZCI6ImV0X2ZIdjVDZmd6WWFrcHpIaWJtWDJVNz
   VvSV9KeEVwQlN2emM1UG9EUFEifSwicHJlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyI
   sImNydiI6IlAtMjU2IiwieCI6Ink5d25JN3pZWXJrY1hwZDVqOU8zcWlSRE14bWhQZE5m
   YlB6SHRMSUxfSDAiLCJ5IjoiQTJBSlhpQVlybFNHZndPTmdmZlhXYU5uVFh4LU1YSVNQR
   lJpd1hNcEVrZyIsImQiOiJaSmNvMnU2aDN5NGc3TTVvdGlWaFRiZkFFVVNETVRraVNrNz
   ZVUmkwNDVjIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRv
   ZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duL
   CBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG
   9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDU
   sImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.37RhnitI5rt3skZ9oRDpeGyxSynhvPxbhxe2_N
   Dm4tQ8audwHH4nV7Qt7wN_vfNvHZ_P3gkiNdrElSMBZcu1Xg~IIpR1uezrjhTgnVU4LY5
   KIdZOjayjRHFP6-ULHDv2ctMVSFTprkTpjvUwkgk1T2vq6IHO5ptkISaglrWLur8vQ~sB
   FFXFVZKVuIoB2SiuyDCBSnC6Zkk10nWfsOn-I1CKAI0NC2QBxloc7gzxG4m4ENSMKKpa9
   FKvyOtoBZi4YK2Q~svvidNTTnZU7D5Kze_SKBRhN3vJiUzs1bPQlK8_PIhqQrFhpKRiOI
   89Qqz6zqGdia1s8IfMYwNPoYJYIlYeNlw~yecfskC44VxcKWgZvUTWOXtp4EZ3kVYKAq1
   f_vCdPsxRkOrEsx7ADTXQtB0ksDhusEbwrqNP8ouNMSaHtKNucw~nMQ5lVAojfiJhzYYd
   KvL7kW35gXuquxrwAwntdjoNzfn7h6do63seUuSx8FUckdKpDGODhWSCQtM6S38oc4Rcw
   ~VXbFtQwnhCRB0jxdVQe1YDahf2fXAsiIvErjzTGbVFw_T_sjN2GZ9uLAyjzyjjXWRwBW
   pZVs8-evVrvWbnPoBA~TP3ATOtrSCGq1Ej_aLMEkFvgnlacq4S5Kx0an3_45jNE9ZrAg9
   Dvm2hEtRQwYF_uEBIL17atsb2jo7y6tLthVQ

           Figure 7: Issued JWP in Compact Serialization (es256)

   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": "mes_BFwj3Xc-T9r74gIlljf-9RWRvt2SV2NXI6HZpjI"
   }

                       Figure 8: Presentation Header

   This header is serialized without whitespace and UTF-8 encoded into
   an octet string.  This gives:

   eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiJtZXNfQkZ3ajNYYy1UOXI3NGdJbGxqZi05UldSdnQyU1YyTlhJNk
   hacGpJIn0

             Figure 9: Presentation Header (base64url-encoded)

Jones, et al.             Expires 24 April 2025                [Page 26]
Internet-Draft            json-proof-algorithms             October 2024

   When signed with the holder's presentation key, the resulting
   signature are:

   8CdaXdSvF4gt1wIO0P5iUKsNrE-KGEcE-myQsgNSmJ8mShMtbZdtnWvIGtLfImZcht_sC
   LiRMFyrkG-DS3x-eA

   |  Figure: Holder Proof-of-Possession (base64url-encoded)

   Then by applying selective disclosure of only the given name and age
   claims (family name and email hidden), we get the following presented
   JPT:

Jones, et al.             Expires 24 April 2025                [Page 27]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "presentation": "eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaX
          BpZW50LmV4YW1wbGUuY29tIiwibm9uY2UiOiJtZXNfQkZ3ajNYYy1UOXI3NGdJ
          bGxqZi05UldSdnQyU1YyTlhJNkhacGpJIn0",
     "issuer": "eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
          Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaW
          x5X25hbWUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292
          ZXJfMjEiXSwicHJvb2Zfa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLC
          J4IjoiVVVJVGRZdVlHRGVQOTdUa2swOHFmUmJHdWhvUjNMZW1RQ1JyV3psUy1E
          byIsInkiOiJJSnhWbVR4Q0lWZU55Q21rNnNIOENlTzd6UnJKMWs2SFFFUFNYS1
          k2SDNjIiwiZCI6ImV0X2ZIdjVDZmd6WWFrcHpIaWJtWDJVNzVvSV9KeEVwQlN2
          emM1UG9EUFEifSwicHJlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydi
          I6IlAtMjU2IiwieCI6Ink5d25JN3pZWXJrY1hwZDVqOU8zcWlSRE14bWhQZE5m
          YlB6SHRMSUxfSDAiLCJ5IjoiQTJBSlhpQVlybFNHZndPTmdmZlhXYU5uVFh4LU
          1YSVNQRlJpd1hNcEVrZyIsImQiOiJaSmNvMnU2aDN5NGc3TTVvdGlWaFRiZkFF
          VVNETVRraVNrNzZVUmkwNDVjIn19",
     "payloads": [
       "MTcxNDUyMTYwMA",
       "MTcxNzE5OTk5OQ",
       "IkRvZSI",
       "IkpheSI",
       "ImpheWRvZUBleGFtcGxlLm9yZyI",
       "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
          VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
          kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
          ImNvdW50cnkiOiJVU0EifQ",
       "dHJ1ZQ",
       null,
       null
     ],
     "proof": [
       "37RhnitI5rt3skZ9oRDpeGyxSynhvPxbhxe2_NDm4tQ8audwHH4nV7Qt7wN_vfNv
          HZ_P3gkiNdrElSMBZcu1Xg",
       "8CdaXdSvF4gt1wIO0P5iUKsNrE-KGEcE-myQsgNSmJ8mShMtbZdtnWvIGtLfImZc
          ht_sCLiRMFyrkG-DS3x-eA",
       "IIpR1uezrjhTgnVU4LY5KIdZOjayjRHFP6-ULHDv2ctMVSFTprkTpjvUwkgk1T2v
          q6IHO5ptkISaglrWLur8vQ",
       "sBFFXFVZKVuIoB2SiuyDCBSnC6Zkk10nWfsOn-I1CKAI0NC2QBxloc7gzxG4m4EN
          SMKKpa9FKvyOtoBZi4YK2Q",
       "svvidNTTnZU7D5Kze_SKBRhN3vJiUzs1bPQlK8_PIhqQrFhpKRiOI89Qqz6zqGdi
          a1s8IfMYwNPoYJYIlYeNlw",
       "yecfskC44VxcKWgZvUTWOXtp4EZ3kVYKAq1f_vCdPsxRkOrEsx7ADTXQtB0ksDhu
          sEbwrqNP8ouNMSaHtKNucw",
       "nMQ5lVAojfiJhzYYdKvL7kW35gXuquxrwAwntdjoNzfn7h6do63seUuSx8FUckdK
          pDGODhWSCQtM6S38oc4Rcw"
     ]
   }

Jones, et al.             Expires 24 April 2025                [Page 28]
Internet-Draft            json-proof-algorithms             October 2024

   |  Figure: Final Presentation in JSON Serialization

   And also in compact serialization:

   eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiJtZXNfQkZ3ajNYYy1UOXI3NGdJbGxqZi05UldSdnQyU1YyTlhJNk
   hacGpJIn0.eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
   vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUi
   LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJvb
   2Zfa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ4IjoiVVVJVGRZdVlHRGVQOT
   dUa2swOHFmUmJHdWhvUjNMZW1RQ1JyV3psUy1EbyIsInkiOiJJSnhWbVR4Q0lWZU55Q21
   rNnNIOENlTzd6UnJKMWs2SFFFUFNYS1k2SDNjIiwiZCI6ImV0X2ZIdjVDZmd6WWFrcHpI
   aWJtWDJVNzVvSV9KeEVwQlN2emM1UG9EUFEifSwicHJlc2VudGF0aW9uX2tleSI6eyJrd
   HkiOiJFQyIsImNydiI6IlAtMjU2IiwieCI6Ink5d25JN3pZWXJrY1hwZDVqOU8zcWlSRE
   14bWhQZE5mYlB6SHRMSUxfSDAiLCJ5IjoiQTJBSlhpQVlybFNHZndPTmdmZlhXYU5uVFh
   4LU1YSVNQRlJpd1hNcEVrZyIsImQiOiJaSmNvMnU2aDN5NGc3TTVvdGlWaFRiZkFFVVNE
   TVRraVNrNzZVUmkwNDVjIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheS
   I~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5
   Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4g
   U3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZ
   SI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ~~.37RhnitI5rt3skZ9oRDpeGyxSy
   nhvPxbhxe2_NDm4tQ8audwHH4nV7Qt7wN_vfNvHZ_P3gkiNdrElSMBZcu1Xg~8CdaXdSv
   F4gt1wIO0P5iUKsNrE-KGEcE-myQsgNSmJ8mShMtbZdtnWvIGtLfImZcht_sCLiRMFyrk
   G-DS3x-eA~IIpR1uezrjhTgnVU4LY5KIdZOjayjRHFP6-ULHDv2ctMVSFTprkTpjvUwkg
   k1T2vq6IHO5ptkISaglrWLur8vQ~sBFFXFVZKVuIoB2SiuyDCBSnC6Zkk10nWfsOn-I1C
   KAI0NC2QBxloc7gzxG4m4ENSMKKpa9FKvyOtoBZi4YK2Q~svvidNTTnZU7D5Kze_SKBRh
   N3vJiUzs1bPQlK8_PIhqQrFhpKRiOI89Qqz6zqGdia1s8IfMYwNPoYJYIlYeNlw~yecfs
   kC44VxcKWgZvUTWOXtp4EZ3kVYKAq1f_vCdPsxRkOrEsx7ADTXQtB0ksDhusEbwrqNP8o
   uNMSaHtKNucw~nMQ5lVAojfiJhzYYdKvL7kW35gXuquxrwAwntdjoNzfn7h6do63seUuS
   x8FUckdKpDGODhWSCQtM6S38oc4Rcw

   |  Figure: Final Presentation in Compact Serialization

A.2.  Example BBS JWP

   The following example uses the BBS algorithm.

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

Jones, et al.             Expires 24 April 2025                [Page 29]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "kty": "EC2",
     "alg": "BBS",
     "use": "proof",
     "crv": "BLS12381G2",
     "x": "CWEcZ-KBjqkcW9Kc1Hn3A7w5qKNpeenbz83LGWxZWOEIHzhdk7ZM1sBSlEcvQ
          yS5EqSnJB6NHQQIsNPtBgehU9UlC3X-Bx-Y26YkIf4ZkTYrlE6TOUhsqxiIthn
          149O8",
     "y": "Ad9MtgXw9dUP26zjRrYZUiMGwP7RedzizTU16xQRF6mwHhduGVISfn5LvxfCJ
          1JpAHbuN3_0bIhCaNTBLDsYBpDPT4YiV6ZfRyT76kMvkMPlIxxqmIG_jtaWzP8
          sFR2p",
     "d": "aeAX6WgqPjlQ_Jpp58jF-NNCCc7M9WGlQx20RUGWEJk"
   }

                  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

   [
       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 12: Example issuer payloads (as members of a JSON array)

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

Jones, et al.             Expires 24 April 2025                [Page 30]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "issuer": "eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRu
          RXhSMERValU4IiwiYWxnIjoiQkJTIn0",
     "payloads": [
       "MTcxNDUyMTYwMA",
       "MTcxNzE5OTk5OQ",
       "IkRvZSI",
       "IkpheSI",
       "ImpheWRvZUBleGFtcGxlLm9yZyI",
       "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
          VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
          kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
          ImNvdW50cnkiOiJVU0EifQ",
       "dHJ1ZQ"
     ],
     "proof": [
       "gPypYJaCrnUwYPrPwRtD47Zk_KKaPc9FcUBs--XzmOF9xoUfQzANn1FdWZWd_1aT
          Zt5l-jSaOtMARFhQrRkMIK-fz1bni7oBBquAEQcU3U8"
     ]
   }

                 Figure 13: Issued JWP (JSON serialization)

   eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRuRXhSMERValU4I
   iwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~Imph
   eWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b
   3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIi
   wibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTI
   zNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.gPypYJaCrnUwYPrPwRtD47Zk_KKaPc9FcU
   Bs--XzmOF9xoUfQzANn1FdWZWd_1aTZt5l-jSaOtMARFhQrRkMIK-fz1bni7oBBquAEQc
   U3U8

               Figure 14: Issued JWP (compact serialization)

   For a presentation with the following presentation header:

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

                   Figure 15: 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 serializations:

Jones, et al.             Expires 24 April 2025                [Page 31]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "presentation": "eyJhbGciOiJCQlMiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC
          5leGFtcGxlLmNvbSIsIm5vbmNlIjoid3JtQlJrS3RYalEifQ",
     "issuer": "eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRu
          RXhSMERValU4IiwiYWxnIjoiQkJTIn0",
     "payloads": [
       "MTcxNDUyMTYwMA",
       "MTcxNzE5OTk5OQ",
       "IkRvZSI",
       "IkpheSI",
       null,
       null,
       null
     ],
     "proof": [
       "iJG8Vt5P9LYtHStXxWF9lbxGi5x3lJ19MsGdrek-66i5ycvEFm1amYe5kjIaZHhg
          iO0H2I1uQlhsyp88-lNLpGOM_XDzZwYqf4HTkLzorpGR5UVJrYLzP4HYAbdPCh
          G8tfv9VxWarRRstGlNleoIf8qkUjvhbHWevX14Hjj102lif5aG4jEh71pYkifm
          UxARJARKboAv2YWO8rCuzSy4NejsK81X6W93KJW8A_Om9z9myaqflqRP0Jp70z
          4r2tYDBVDaOLCMd5DadMR6cfFkKDQMx-qCtb6rqxWRXwupEfie3PmRGHtOtJFN
          7RZAv-TcQFREFqMnc80VYJFJhsbzaPjsSDcfyP-omMbr9bIg4F4wTFHrAtlFVY
          Y_YdG_07DczJcTv35A6EdIaTpy9q_NCGlTj_wdRh0p3uNjZAKDG7as9dyQCzRA
          LwiheQL03gtiTx4USV8yo2UXdsG-5hba4EYMs3YN2iwStQh91ZfzXRw"
     ]
   }

              Figure 16: Presentation JWP (JSON serialization)

   eyJhbGciOiJCQlMiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC5leGFtcGxlLmNvbSIsI
   m5vbmNlIjoid3JtQlJrS3RYalEifQ.eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJ
   UOVJiYm5yb2JwdGRuRXhSMERValU4IiwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxN
   zE5OTk5OQ~IkRvZSI~IkpheSI~~~.iJG8Vt5P9LYtHStXxWF9lbxGi5x3lJ19MsGdrek-
   66i5ycvEFm1amYe5kjIaZHhgiO0H2I1uQlhsyp88-lNLpGOM_XDzZwYqf4HTkLzorpGR5
   UVJrYLzP4HYAbdPChG8tfv9VxWarRRstGlNleoIf8qkUjvhbHWevX14Hjj102lif5aG4j
   Eh71pYkifmUxARJARKboAv2YWO8rCuzSy4NejsK81X6W93KJW8A_Om9z9myaqflqRP0Jp
   70z4r2tYDBVDaOLCMd5DadMR6cfFkKDQMx-qCtb6rqxWRXwupEfie3PmRGHtOtJFN7RZA
   v-TcQFREFqMnc80VYJFJhsbzaPjsSDcfyP-omMbr9bIg4F4wTFHrAtlFVYY_YdG_07Dcz
   JcTv35A6EdIaTpy9q_NCGlTj_wdRh0p3uNjZAKDG7as9dyQCzRALwiheQL03gtiTx4USV
   8yo2UXdsG-5hba4EYMs3YN2iwStQh91ZfzXRw

            Figure 17: Presentation JWP (compact serialization)

A.3.  Example MAC JWP

   The following example uses the MAC-H256 algorithm.

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

Jones, et al.             Expires 24 April 2025                [Page 32]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "rljcEFI0caNXx29jNkyLXtbPti5qHkokC6PWy9XYAeM",
     "y": "I6OlSc34yeKQMvXvq4aV6M12ESAK9RkdArMIeAWi70M",
     "d": "xa0e8RpopMldqZCT7g9-2gDlWM1PrHz1N-qoQOcXU6U"
   }

                       Figure 18: Issuer private key

   This is the Issuer's ephemerally generated shared secret:

   "SFTuoixBgWpEjVC5SoNeklAanEpeRV5fHb2YmKBQ5yM"

                          Figure 19: Shared Secret

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

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "y9wnI7zYYrkcXpd5j9O3qiRDMxmhPdNfbPzHtLIL_H0",
     "y": "A2AJXiAYrlSGfwONgffXWaNnTXx-MXISPFRiwXMpEkg",
     "d": "ZJco2u6h3y4g7M5otiVhTbfAEUSDMTkiSk76URi045c"
   }

                       Figure 20: Holder private key

   For the following protected header and array of payloads:

Jones, et al.             Expires 24 April 2025                [Page 33]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "alg": "MAC-H256",
     "typ": "JPT",
     "iss": "https://issuer.example",
     "claims": [
       "iat",
       "exp",
       "family_name",
       "given_name",
       "email",
       "address",
       "age_over_21"
     ],
     "presentation_key": {
       "kty": "EC",
       "crv": "P-256",
       "use": "sign",
       "x": "y9wnI7zYYrkcXpd5j9O3qiRDMxmhPdNfbPzHtLIL_H0",
       "y": "A2AJXiAYrlSGfwONgffXWaNnTXx-MXISPFRiwXMpEkg"
     }
   }

                 Figure 21: Example issuer protected 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 22: Example issuer payloads (as members of a JSON array)

   The first MAC is generated using the key issuer_header and a value of
   the issuer protected header as a UTF-8 encoded octet string.  This
   results in the following MAC:

   GelNfHfj1MvbSqvtMLLrax2EWZa8Vk-kx3DvPU7yo6M

Jones, et al.             Expires 24 April 2025                [Page 34]
Internet-Draft            json-proof-algorithms             October 2024

       Figure 23: Issuer MAC of protected header (base64url-encoded)

   The issuer generates an array of derived keys with one for each
   payload by using the shared secret as the key, and the index of the
   payload (as payload_{n} in UTF-8 encoded octets) as the input in a
   HMAC operation.  This results in the following set of derived keys:

   [
     "YCXErQ0PO-_xVqoUJXU1GpBkLiKLUnRSPq9VNTGf3oo",
     "fv76c2D2DkSVuV-wgzeNqt3mZTgJx_20K53LwRLbZPM",
     "lloGHG190wV9wb3AC5rwbgR4qboSKHLG8dj63S4fYCA",
     "UweEuEuHjhIL7Ot_S9R6qavLB3aUb7iwm3_Lr9aCpIg",
     "DVGt1Km7Ff5KSHlgm-dK2ZVx9QwReBS5TyFa_QwYGdM",
     "EBpCbeRdjPUqE3ikQJpEbwI3cd2SbL0Ygs61worKOzY",
     "7qLtlKgAc6PZKZPKzhZStaMB-0HfEdcQdlofpf2gyy4"
   ]

            Figure 24: 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:

   [
     "1YXUWZyWBUppXWc5ORe-4qHT-UHm4HGJtf_M3kAeWDo",
     "Im8KqIkA1jLM05jWHCVgM_x2NBgiFl1UwV6e5VmEu6g",
     "MVcytkCkQQCbtKorAAcFJ7ykGJhXwUo28WUjt5WPLjM",
     "J4opViBopeg3w9lWjqU1VDe-aeEObjM9RgGdPa7Qido",
     "T8TA_7VIvggxX6awElx5zsBIdnSMMHxJj3VnlEwOC3E",
     "k1V5j6UGQRGIqHfzPdGSqCyPimLmUkVcizwRx7ZwArs",
     "kNNUdBSfbsJI0fQENUejx7dfMDyvSr7HlhlzBnUD6oo"
   ]

             Figure 25: Payload MAC values (base64url-encoded)

   The issuer protected header MAC and the payload MAC octet strings are
   concatenated into a single value known as the combined 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.

   [
     "4XWYLmnuc-J8PESgWfVMhcECJaLHuAohKymCfdc0pfMIqGYjDNqMQCJFU2nzltRk6K
   E31ELCI8iUW2MV4eHPfA",
     "oYLUf--sI9Ej2nDp-DiAMXe98MQEMMXSASw2zHUjETE"
   ]

Jones, et al.             Expires 24 April 2025                [Page 35]
Internet-Draft            json-proof-algorithms             October 2024

                Figure 26: Issued Proof (base64url-encoded)

   The final issued JWP in JSON serialization is:

   {
     "issuer": "eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
   Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hb
   WUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicH
   Jlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2l
   nbiIsIngiOiJ5OXduSTd6WVlya2NYcGQ1ajlPM3FpUkRNeG1oUGROZmJQekh0TElMX0gw
   IiwieSI6IkEyQUpYaUFZcmxTR2Z3T05nZmZYV2FOblRYeC1NWElTUEZSaXdYTXBFa2cif
   X0",
     "payloads": [
       "MTcxNDUyMTYwMA",
       "MTcxNzE5OTk5OQ",
       "IkRvZSI",
       "IkpheSI",
       "ImpheWRvZUBleGFtcGxlLm9yZyI",
       "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
   VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBb
   nl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOi
   JVU0EifQ",
       "dHJ1ZQ"
     ],
     "proof": [
       "4XWYLmnuc-J8PESgWfVMhcECJaLHuAohKymCfdc0pfMIqGYjDNqMQCJFU2nzltRk
   6KE31ELCI8iUW2MV4eHPfA",
       "oYLUf--sI9Ej2nDp-DiAMXe98MQEMMXSASw2zHUjETE"
     ]
   }

               Figure 27: Issued JWP (in JSON serialization)

   The same JWP in compact serialization:

   eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
   mV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUiLCJnaXZlbl
   9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJlc2VudGF0aW9
   uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2lnbiIsIngiOiJ5
   OXduSTd6WVlya2NYcGQ1ajlPM3FpUkRNeG1oUGROZmJQekh0TElMX0gwIiwieSI6IkEyQ
   UpYaUFZcmxTR2Z3T05nZmZYV2FOblRYeC1NWElTUEZSaXdYTXBFa2cifX0.MTcxNDUyMT
   YwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb
   3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3
   RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiw
   icmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~d
   HJ1ZQ.4XWYLmnuc-J8PESgWfVMhcECJaLHuAohKymCfdc0pfMIqGYjDNqMQCJFU2nzltR
   k6KE31ELCI8iUW2MV4eHPfA~oYLUf--sI9Ej2nDp-DiAMXe98MQEMMXSASw2zHUjETE

Jones, et al.             Expires 24 April 2025                [Page 36]
Internet-Draft            json-proof-algorithms             October 2024

              Figure 28: Issued JWP (in compact serialization)

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

   For presentation with the following presentation protected header:

   {
     "alg": "MAC-H256",
     "aud": "https://recipient.example.com",
     "nonce": "mes_BFwj3Xc-T9r74gIlljf-9RWRvt2SV2NXI6HZpjI"
   }

                  Figure 29: 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 the disclosed payloads, the holder will provide the corresponding
   derived key.  For the non-disclosed payloads, 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:

   [
     "bC1SXUSv9lVozHrbaYI2FtMgT1CjPySTee8LE261p_fRyxqFuF4b8eTMSkGsFxBS00
   vtxeUK_vqySxUo2e6VeA",
     "4XWYLmnuc-J8PESgWfVMhcECJaLHuAohKymCfdc0pfMIqGYjDNqMQCJFU2nzltRk6K
   E31ELCI8iUW2MV4eHPfA",
     "YCXErQ0PO-_xVqoUJXU1GpBkLiKLUnRSPq9VNTGf3oo",
     "fv76c2D2DkSVuV-wgzeNqt3mZTgJx_20K53LwRLbZPM",
     "lloGHG190wV9wb3AC5rwbgR4qboSKHLG8dj63S4fYCA",
     "UweEuEuHjhIL7Ot_S9R6qavLB3aUb7iwm3_Lr9aCpIg",
     "T8TA_7VIvggxX6awElx5zsBIdnSMMHxJj3VnlEwOC3E",
     "k1V5j6UGQRGIqHfzPdGSqCyPimLmUkVcizwRx7ZwArs",
     "kNNUdBSfbsJI0fQENUejx7dfMDyvSr7HlhlzBnUD6oo"
   ]

             Figure 30: Presentation proof (base64url-encoded)

   The final presented JWP in JSON serialization is:

Jones, et al.             Expires 24 April 2025                [Page 37]
Internet-Draft            json-proof-algorithms             October 2024

   {
     "presentation": "eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaX
   BpZW50LmV4YW1wbGUuY29tIiwibm9uY2UiOiJtZXNfQkZ3ajNYYy1UOXI3NGdJbGxqZi0
   5UldSdnQyU1YyTlhJNkhacGpJIn0",
     "issuer": "eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
   Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hb
   WUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicH
   Jlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2l
   nbiIsIngiOiJ5OXduSTd6WVlya2NYcGQ1ajlPM3FpUkRNeG1oUGROZmJQekh0TElMX0gw
   IiwieSI6IkEyQUpYaUFZcmxTR2Z3T05nZmZYV2FOblRYeC1NWElTUEZSaXdYTXBFa2cif
   X0",
     "payloads": [
       "MTcxNDUyMTYwMA",
       "MTcxNzE5OTk5OQ",
       "IkRvZSI",
       "IkpheSI",
       null,
       null,
       null
     ],
     "proof": [
       "bC1SXUSv9lVozHrbaYI2FtMgT1CjPySTee8LE261p_fRyxqFuF4b8eTMSkGsFxBS
   00vtxeUK_vqySxUo2e6VeA",
       "4XWYLmnuc-J8PESgWfVMhcECJaLHuAohKymCfdc0pfMIqGYjDNqMQCJFU2nzltRk
   6KE31ELCI8iUW2MV4eHPfA",
       "YCXErQ0PO-_xVqoUJXU1GpBkLiKLUnRSPq9VNTGf3oo",
       "fv76c2D2DkSVuV-wgzeNqt3mZTgJx_20K53LwRLbZPM",
       "lloGHG190wV9wb3AC5rwbgR4qboSKHLG8dj63S4fYCA",
       "UweEuEuHjhIL7Ot_S9R6qavLB3aUb7iwm3_Lr9aCpIg",
       "T8TA_7VIvggxX6awElx5zsBIdnSMMHxJj3VnlEwOC3E",
       "k1V5j6UGQRGIqHfzPdGSqCyPimLmUkVcizwRx7ZwArs",
       "kNNUdBSfbsJI0fQENUejx7dfMDyvSr7HlhlzBnUD6oo"
     ]
   }

              Figure 31: Presented JWP (in JSON serialization)

   The same JWP in compact serialization:

Jones, et al.             Expires 24 April 2025                [Page 38]
Internet-Draft            json-proof-algorithms             October 2024

   eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
   29tIiwibm9uY2UiOiJtZXNfQkZ3ajNYYy1UOXI3NGdJbGxqZi05UldSdnQyU1YyTlhJNk
   hacGpJIn0.eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
   vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUi
   LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJlc
   2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2lnbi
   IsIngiOiJ5OXduSTd6WVlya2NYcGQ1ajlPM3FpUkRNeG1oUGROZmJQekh0TElMX0gwIiw
   ieSI6IkEyQUpYaUFZcmxTR2Z3T05nZmZYV2FOblRYeC1NWElTUEZSaXdYTXBFa2cifX0.
   MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.bC1SXUSv9lVozHrbaYI2
   FtMgT1CjPySTee8LE261p_fRyxqFuF4b8eTMSkGsFxBS00vtxeUK_vqySxUo2e6VeA~4X
   WYLmnuc-J8PESgWfVMhcECJaLHuAohKymCfdc0pfMIqGYjDNqMQCJFU2nzltRk6KE31EL
   CI8iUW2MV4eHPfA~YCXErQ0PO-_xVqoUJXU1GpBkLiKLUnRSPq9VNTGf3oo~fv76c2D2D
   kSVuV-wgzeNqt3mZTgJx_20K53LwRLbZPM~lloGHG190wV9wb3AC5rwbgR4qboSKHLG8d
   j63S4fYCA~UweEuEuHjhIL7Ot_S9R6qavLB3aUb7iwm3_Lr9aCpIg~T8TA_7VIvggxX6a
   wElx5zsBIdnSMMHxJj3VnlEwOC3E~k1V5j6UGQRGIqHfzPdGSqCyPimLmUkVcizwRx7Zw
   Ars~kNNUdBSfbsJI0fQENUejx7dfMDyvSr7HlhlzBnUD6oo

            Figure 32: Presented JWP (in 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 ]]

   -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.

Jones, et al.             Expires 24 April 2025                [Page 39]
Internet-Draft            json-proof-algorithms             October 2024

   *  Moved the registry for proof_key and presentation_key to JWP where
      they are defined.  Consolidated usage, purpose and requirements
      from algorith musage 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

   *  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.

Jones, et al.             Expires 24 April 2025                [Page 40]
Internet-Draft            json-proof-algorithms             October 2024

   -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

   Jeremie Miller
   Ping Identity
   Email: jmiller@pingidentity.com

Jones, et al.             Expires 24 April 2025                [Page 41]