JSON Proof Algorithms

Internet-Draft	json-proof-algorithms	June 2025
Jones, et al.	Expires 26 December 2025	[Page]

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.¶

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.¶

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.¶

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.¶

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.¶

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 CBOR serialization and a zero-length string in compact serialization.¶

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. 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.¶

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"}'¶

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 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:¶

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¶

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. 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 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.¶
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¶
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¶
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¶

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": "kw7CK-13yQbSt2p_3DfSyDKmJAxWP1Pp_qiimQUq-F0",
  "y": "aniIEfntdBfQOg44T-K5avCbnlox4pDdSvR6BMypGyU",
  "d": "T46FFrH_nuXB-YvePX-pWETDs6vWEHFq0tu4P6RQZKg"
}

Figure 1: Issuer Private Key (ES256 in JWK)

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

{
  "kty": "EC",
  "crv": "P-256",
  "x": "CRQFJy8WHeMBc0HPiFCDKqH9Kk-IZqlCQnJlUBAbowA",
  "y": "8GWfF7FCey3rW8D8bX_hEu8sLOx_doYP9YqFwXJqqXI",
  "d": "7rkepzBCL8J_f4ymgHMOUjRXwVkDlsCmejMGkcKfT1M"
}

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": "2teBV-VnJKlSpP5C-KAsZh0Zb9Jd42SDoceEQ2pCwlI",
  "y": "y_pejqcHIyjmYRBhjWfYfkw3l6uhot0PgkvFZb6iPqo",
  "d": "DnsdE-IwGr2CwMJ641MpNwyN_hjxih0ehd9aBJwjlMg"
}

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

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

{
  "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": "CRQFJy8WHeMBc0HPiFCDKqH9Kk-IZqlCQnJlUBAbowA",
    "y": "8GWfF7FCey3rW8D8bX_hEu8sLOx_doYP9YqFwXJqqXI"
  },
  "presentation_key": {
    "kty": "EC",
    "crv": "P-256",
    "x": "2teBV-VnJKlSpP5C-KAsZh0Zb9Jd42SDoceEQ2pCwlI",
    "y": "y_pejqcHIyjmYRBhjWfYfkw3l6uhot0PgkvFZb6iPqo"
  }
}

Figure 4: Issuer Protected header (SU-ES256, JSON)
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Figure 5: Encoded Issuer Protected Header (SU-ES256, JSON, encoded)

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

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

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

Figure 6: Issuer payloads (JSON, as array)

The compact serialization of the same JPT is:¶
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.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~Imp
heWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0
b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuI
iwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MT
IzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.md1l5L-nqREhiCtCKvNKQ82S2L0JoGpbt
fKrqaZteWLkvb_JOzKaB2fUfJuS1dmW9FYusLSmUVxSJ2-ROfB8aA~BgyVqKmdYmL72Ag
CBW1ZDVrk5aPjPrWTxHC7er0pBO4os4mrmsIE7D4cmrNwJgskAZo7w7TaGNqo1l2EICz0
7g~mg0yddhxclixHsI8vDxTGWiwXCDG7I8tTNk3JYqi05vvR1hVv0fWv5ex9Sgnv7TgVj
XcuWLBijQQd6OfRDZR3A~Jmtw7gvFtv4He_oA0YACQ8NaZkhETxGeMPSD578YVDcf1dbi
XPC7qmZtLTMT9KvThmEYU4Rj4-3u6HZibYcYfw~vur0A2vW9zoqHQpF4lAsleiY-tMA09
t7BfuAS7FMk-qnXgvuqLwI9usA5AmmVDGgN4gXnhglvyFN4Cn_GIFhEg~zVUPdGT4DPfS
OSM9EZevEbUGx-qmBhYIAOwIEYqIJxfe7AWBTRVw408HF-V6_hBFGWzeDmBigzcBc6i96
baHkw~dX9XWaz8m1k9xjRKGBr-T3sBosUUvtRkXbGWnd4FelfDX83rwUD1igYulLm5lXz
xBWXZkDQlTqdFOZHPt85umQ~0r9el-N4yGmGaKjez2ZQE7xqGHahXM23ZLdu1dEnGyX8Y
7PxZFPrKCkV41Esa7Mn4EEh7MWVBnQPCu0EI5Gkeg

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": "C72Q0mJLp-WjNn2veaakrzf7kUEsbOAH_NNPWtm_BTY"
}

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

eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJDNzJRMG1KTHAtV2pObjJ2ZWFha3J6ZjdrVUVzYk9BSF9OTlBXdG
1fQlRZIn0

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

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

XRtOXRpQ8UjFM8FCZucn_kg0bDUVM98DO_FH-uufWMiNv2BHaJWPry0QY7R4311FBSslZ
U2czKvAMyYalu7eDg

Figure: Holder Proof-of-Possession (SU-ES256, JSON)¶

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

eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJDNzJRMG1KTHAtV2pObjJ2ZWFha3J6ZjdrVUVzYk9BSF9OTlBXdG
1fQlRZIn0.eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUi
LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJvb
2Zfa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ4IjoiQ1JRRkp5OFdIZU1CYz
BIUGlGQ0RLcUg5S2stSVpxbENRbkpsVUJBYm93QSIsInkiOiI4R1dmRjdGQ2V5M3JXOEQ
4YlhfaEV1OHNMT3hfZG9ZUDlZcUZ3WEpxcVhJIn0sInByZXNlbnRhdGlvbl9rZXkiOnsi
a3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOiIydGVCVi1WbkpLbFNwUDVDLUtBc1poM
FpiOUpkNDJTRG9jZUVRMnBDd2xJIiwieSI6InlfcGVqcWNISXlqbVlSQmhqV2ZZZmt3M2
w2dWhvdDBQZ2t2RlpiNmlQcW8ifX0.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~I
kpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3
QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1
haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxf
Y29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ~~.md1l5L-nqREhiCtCKvNKQ
82S2L0JoGpbtfKrqaZteWLkvb_JOzKaB2fUfJuS1dmW9FYusLSmUVxSJ2-ROfB8aA~XRt
OXRpQ8UjFM8FCZucn_kg0bDUVM98DO_FH-uufWMiNv2BHaJWPry0QY7R4311FBSslZU2c
zKvAMyYalu7eDg~BgyVqKmdYmL72AgCBW1ZDVrk5aPjPrWTxHC7er0pBO4os4mrmsIE7D
4cmrNwJgskAZo7w7TaGNqo1l2EICz07g~mg0yddhxclixHsI8vDxTGWiwXCDG7I8tTNk3
JYqi05vvR1hVv0fWv5ex9Sgnv7TgVjXcuWLBijQQd6OfRDZR3A~Jmtw7gvFtv4He_oA0Y
ACQ8NaZkhETxGeMPSD578YVDcf1dbiXPC7qmZtLTMT9KvThmEYU4Rj4-3u6HZibYcYfw~
vur0A2vW9zoqHQpF4lAsleiY-tMA09t7BfuAS7FMk-qnXgvuqLwI9usA5AmmVDGgN4gXn
hglvyFN4Cn_GIFhEg~zVUPdGT4DPfSOSM9EZevEbUGx-qmBhYIAOwIEYqIJxfe7AWBTRV
w408HF-V6_hBFGWzeDmBigzcBc6i96baHkw

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 and claims from [I-D.maldant-spice-oidc-cwt], illustrated using [I-D.ietf-cbor-edn-literals] (EDN).¶

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

{          / 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: {      / proof key /
    1: 2,   / kty : "EC2" /
    -1: 1,  / crv: "P-256" /
    -2: h'dad78157e56724a952a4fe42f8a02c661d196fd25de36483a1c78443' +
        h'6a42c252', / x /
    -3: h'cbfa5e8ea7072328e66110618d67d87e4c3797aba1a2dd0f824bc565' +
        h'bea23eaa'  / y /
  },
  9: {      / presentation key /
    1: 2,   / kty: "EC2" /
    -1: 1,  / crv: "P-256" /
    -2: h'091405272f161de3017341cf8850832aa1fd2a4f8866a94242726550' +
        h'101ba300', / x /
    -3: h'f0659f17b1427b2deb5bc0fc6d7fe112ef2c2cec7f76860ff58a85c1' +
        h'726aa972'  / y /
  }
}

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

[ / 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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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'0bbd90d2624ba7e5a3367daf79a6a4af37fb91412c6ce007fcd34f5ad9bf0536', / nonce /
}

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

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

845846a3010106781d68747470733a2f2f726563697069656e742e6578616d70
6c652e636f6d0758200bbd90d2624ba7e5a3367daf79a6a4af37fb91412c6ce0
07fcd34f5ad9bf053658cda601010314057668747470733a2f2f697373756572
2e6578616d706c650687060418aa18ab18b318bb6b6167655f6f7665725f3231
08a401022001215820dad78157e56724a952a4fe42f8a02c661d196fd25de364
83a1c784436a42c252225820cbfa5e8ea7072328e66110618d67d87e4c3797ab
a1a2dd0f824bc565bea23eaa09a401022001215820091405272f161de3017341
cf8850832aa1fd2a4f8866a94242726550101ba300225820f0659f17b1427b2d
eb5bc0fc6d7fe112ef2c2cec7f76860ff58a85c1726aa972891a0a3827001a0a
3c3d3f63446f65634a6179726a6179646f65406578616d706c652e6f7267a601
782331323334204d61696e2053742e0a416e79746f776e2c2043412031323334
350a555341026d31323334204d61696e2053742e0367416e79746f776e046243
41056539303231300663555341f5f6f6875840046ab128f3c69d5f6b0b2b6475
37642e4252d1acde4b4d35a325f25ec34504d80895c6296648c6a511fe632a55
f96917ec36001f1c29b91e6320b102b8c4a4bb5840ad70c9b5c5e3e80ddd31d9
e120dcacbcd015b7a48f36fad0d3a8f3a4b435ba26d6e71c4e31ca39cd1c7458
8334e210242c653aa252ead4a0bb4f466c200d764d5840b9d325b5950c3e6127
2db91880c707ffdbf8ac073eb1bb42af3480cfbf13150b9e7d1b9c40670267af
b5fb9095f66eb5b179992123daebc374a31fafa7dae70b5840f7f1e39f9de08a
4c39502cc6143dff08564a0ee895fc107c1fc030bf6827507cd6043a9d95c22f
2b19d258ccf880c368aeaba294f1b0b8446f57855a2777af945840d1ac2ca536
942d02254bc44122d526932570636294be5709b392c6f2aa9892ffdbe78c3070
14316ef3b8bde7ff5087e99d4d1b7de3163e10bc4b06e4a1ac1e0b584065a220
4795fcfb6057813fef1ce8e66776fb5205cc0d0b303121fe32a3925c6c04fb29
dc1b05304548a2ac556ad533a223a4e199b54cc94f44b4f324fb05ae76584063
e0e92898def91c84f5334e152ea613b0de4d8dc903735b6cbeaf75699461c09d
c8f334ef3cd959217e5fcfc62c03a55b1bee621791969d48626610dda277b4

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": "EC2",
  "alg": "BBS",
  "use": "proof",
  "crv": "BLS12381G2",
  "x": "EXAG-811fOsWJDfKGN12Jai0TGRQ_Kaj4cJbhfXJAt02_AIlGtYe4K-fu5trY
       jcVC1P1c2LZy1ZKNozK6qe7evV_bg2NrGz_C6AmBLMYVL_S7P4fFO9NavagMB3
       xYqbE",
  "y": "DOvLqADzpd8zqIM7flLMr7vkxMC0NX_J0rzYEIidZgWDMgBvhn0gTusFaqESW
       ChWD9O5IswTDi6kysz3f-Qk6Zu3MaUHQb7rz3jPSCxOpdTy5njfisal2w2SPwQ
       3gPw3",
  "d": "A8GWUlnRPH2IVCjMJFIzxcr_0SBcCSvvPaQNj0MqexA"
}

Figure 10: BBS private key in JWK format

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

For the following protected header and array of payloads:¶

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

Figure 11: Example issuer protected header

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

eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRuRXhSMERValU4I
iwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~Imph
eWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b
3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIi
wibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTI
zNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.mYaetEmrtu4kJ03CAPudFYdTEpBMckiHlj
UezOyE9cuSV0axBC7mKIizFL9WWVOZH--kYwEpVlsBGrQpNr8gdybTnLQ5SmYFr5ou25K
pGRk

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: Holder Presentation Header

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

eyJhbGciOiJCQlMiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC5leGFtcGxlLmNvbSIsI
m5vbmNlIjoid3JtQlJrS3RYalEifQ.eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJ
UOVJiYm5yb2JwdGRuRXhSMERValU4IiwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxN
zE5OTk5OQ~IkRvZSI~IkpheSI~~~.jR6PxUS_11_7F66QmFSuzQijwMSL4Gk2DDtj5xMs
j6XA-cAqEr0SEMJJmrBBPco9mGUcuN3fz4QDKxMbim9i4oNqyHtFZy9GHVN0y3Idwa82S
mHf8g_72gImYabs97i6lxDkUnPpWy0NHbBqxfo4SN3QCQqu1r1ig2sEr5CYWeQ11qkAvK
JJd0kZAI-MZLMLSD_PntHeTdjg7vm8Ct4QVEMoGonIO8K3NtfvzLAnPcZEJrtXhBx7iOi
wxTKQQTPD1JvQGtYwq9DDn8_EpLdSQDZx48cReJL6wgZ6K09scClMa_x11nRJz3VUJRuw
vu97BbVS2GaMYHPe2frPNKvjUa58p7Z2DaqAUD3JsKh63qA_VKD3bCvwqBbNLYLph3KMU
V_eqK31GEPff2x3v3gzECEH_U7tc2tT59Xf0oQFLu6Kf4OawYgAq_970LDnR76wDy0RvE
djAeW2I-h8yUy1z-H5Fhde6vI4Efzank4NpHs

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": "kw7CK-13yQbSt2p_3DfSyDKmJAxWP1Pp_qiimQUq-F0",
  "y": "aniIEfntdBfQOg44T-K5avCbnlox4pDdSvR6BMypGyU",
  "d": "T46FFrH_nuXB-YvePX-pWETDs6vWEHFq0tu4P6RQZKg"
}

Figure 15: Issuer private key

This is the Issuer's ephemerally generated shared secret:¶

"z3WkWLK0YtIPIt4tAgNqVeOdTXhEj0NR9r6kgxBom2M"

Figure 16: Shared Secret

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

{
  "kty": "EC",
  "crv": "P-256",
  "x": "2teBV-VnJKlSpP5C-KAsZh0Zb9Jd42SDoceEQ2pCwlI",
  "y": "y_pejqcHIyjmYRBhjWfYfkw3l6uhot0PgkvFZb6iPqo",
  "d": "DnsdE-IwGr2CwMJ641MpNwyN_hjxih0ehd9aBJwjlMg"
}

Figure 17: Holder private key

For the following protected header and array of payloads:¶

{
  "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": "2teBV-VnJKlSpP5C-KAsZh0Zb9Jd42SDoceEQ2pCwlI",
    "y": "y_pejqcHIyjmYRBhjWfYfkw3l6uhot0PgkvFZb6iPqo"
  }
}

Figure 18: 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 19: 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:¶

QNUPgVtyjcY4wxozUBVqGkP-2Bt1MEuYCn5yLGKLkJs

Figure 20: 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:¶

[
  "UwE0lIrRVoVsqa9ZS5k4-_ksLkglCFCyeh_HAsTbJdQ",
  "9tMg4rLdxKMZfFqx48YKrJKB-oAWI8yQoPQV_l_UbwQ",
  "HBucl_LdtJTGfYYF04Zm8GOBOJ8DIADKTooCLh9xuqc",
  "NBu9SlenuXk1dp-tIhXbQdCM31wvrjWvcBogMdG41oM",
  "wUL-U6CKuhKg2bc7F3WDBDUuc8fUUcxbdxAKMHe-aRc",
  "aqQWYIvK4yCSl7KUwjTpJijEJ5spSj-NU4hzfqHv9kE",
  "2mw_9qV-vyaJexHoZlIARBL_nMEaXWNS0uZvpUZVKEg"
]

Figure 21: 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:¶

[
  "iluKO6JqSf7qI6zNM0v4Dnj3Ma6vNm45AtvIHLpqD1M",
  "u6t2bzpdDxdn3iB65K__uPyDx9hIJgnfxKANx9VK_84",
  "NLaGCdtu2sUbasvx1b9awr3KMb6IIOFrrRsQ7ACwnqk",
  "Xg0ZYslhSFdVRa_ZwMsZTKSUKeZ2o9EGYG7ddsEROvg",
  "Uv3kljpVk9AyhdaOj-C8_f_-LmIcjqz-OBUwHZXBgdw",
  "tKmKszO_hDXchIAGs14G6AZkpmbaymLtQImYyTv2hio",
  "jUqqNZ4eaYjaJS8bjYX0rCRSiPIRIKuTjcMtvk9OYiA"
]

Figure 22: 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.¶

[
  "XnsOUfStHyF8IQpA0lk6olECRZweuSqJd0tWQ5Y8C1k0_MGvz7WoOsDcFGkjK0IOYT
FJ5io6TwA3HHvUQpvrgw",
  "kpugfqcVmNBM14oa4ClFlOdPg68wdzz6izfUGSJgtyk"
]

Figure 23: Issued Proof (Base64url-Encoded)

The final issued JWP in compact serialization is:¶

eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
mV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUiLCJnaXZlbl
9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJlc2VudGF0aW9
uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2lnbiIsIngiOiIy
dGVCVi1WbkpLbFNwUDVDLUtBc1poMFpiOUpkNDJTRG9jZUVRMnBDd2xJIiwieSI6Inlfc
GVqcWNISXlqbVlSQmhqV2ZZZmt3M2w2dWhvdDBQZ2t2RlpiNmlQcW8ifX0.MTcxNDUyMT
YwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb
3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3
RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiw
icmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~d
HJ1ZQ.XnsOUfStHyF8IQpA0lk6olECRZweuSqJd0tWQ5Y8C1k0_MGvz7WoOsDcFGkjK0I
OYTFJ5io6TwA3HHvUQpvrgw~kpugfqcVmNBM14oa4ClFlOdPg68wdzz6izfUGSJgtyk

Figure 24: Issued JWP (MAC-H256, JSON, Compact Serialization)

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

For presentation with the following presentation protected header:¶

{
  "alg": "MAC-H256",
  "aud": "https://recipient.example.com",
  "nonce": "C72Q0mJLp-WjNn2veaakrzf7kUEsbOAH_NNPWtm_BTY"
}

Figure 25: 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:¶

[
  "LV3RC7dxjG6FC3O0MrCYtwBZWIrGabT4rjVIABBBN0zpkUma9VlLXjy4wsx21YfyN5
U1nObaEsBLM49gKefbBw",
  "XnsOUfStHyF8IQpA0lk6olECRZweuSqJd0tWQ5Y8C1k0_MGvz7WoOsDcFGkjK0IOYT
FJ5io6TwA3HHvUQpvrgw",
  "UwE0lIrRVoVsqa9ZS5k4-_ksLkglCFCyeh_HAsTbJdQ",
  "9tMg4rLdxKMZfFqx48YKrJKB-oAWI8yQoPQV_l_UbwQ",
  "HBucl_LdtJTGfYYF04Zm8GOBOJ8DIADKTooCLh9xuqc",
  "NBu9SlenuXk1dp-tIhXbQdCM31wvrjWvcBogMdG41oM",
  "Uv3kljpVk9AyhdaOj-C8_f_-LmIcjqz-OBUwHZXBgdw",
  "tKmKszO_hDXchIAGs14G6AZkpmbaymLtQImYyTv2hio",
  "jUqqNZ4eaYjaJS8bjYX0rCRSiPIRIKuTjcMtvk9OYiA"
]

Figure 26: Presentation proof (Base64url-Encoded)

The final presented JWP in compact serialization is:¶

eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJDNzJRMG1KTHAtV2pObjJ2ZWFha3J6ZjdrVUVzYk9BSF9OTlBXdG
1fQlRZIn0.eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUi
LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJlc
2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2lnbi
IsIngiOiIydGVCVi1WbkpLbFNwUDVDLUtBc1poMFpiOUpkNDJTRG9jZUVRMnBDd2xJIiw
ieSI6InlfcGVqcWNISXlqbVlSQmhqV2ZZZmt3M2w2dWhvdDBQZ2t2RlpiNmlQcW8ifX0.
MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.LV3RC7dxjG6FC3O0MrCY
twBZWIrGabT4rjVIABBBN0zpkUma9VlLXjy4wsx21YfyN5U1nObaEsBLM49gKefbBw~Xn
sOUfStHyF8IQpA0lk6olECRZweuSqJd0tWQ5Y8C1k0_MGvz7WoOsDcFGkjK0IOYTFJ5io
6TwA3HHvUQpvrgw~UwE0lIrRVoVsqa9ZS5k4-_ksLkglCFCyeh_HAsTbJdQ~9tMg4rLdx
KMZfFqx48YKrJKB-oAWI8yQoPQV_l_UbwQ~HBucl_LdtJTGfYYF04Zm8GOBOJ8DIADKTo
oCLh9xuqc~NBu9SlenuXk1dp-tIhXbQdCM31wvrjWvcBogMdG41oM~Uv3kljpVk9Ayhda
Oj-C8_f_-LmIcjqz-OBUwHZXBgdw~tKmKszO_hDXchIAGs14G6AZkpmbaymLtQImYyTv2
hio~jUqqNZ4eaYjaJS8bjYX0rCRSiPIRIKuTjcMtvk9OYiA

Figure 27: Presented JWP (MAC-H256, JSON, Compact Serialization)