JSON Proof Algorithms

Internet-Draft	json-proof-algorithms	October 2024
Jones, et al.	Expires 24 April 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 JSON 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 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": "V3cpRRv0e44j0E2BU6l9oHJnl7HIpx41PlgjKC2YSNA",
  "y": "4A6HnHEDNGM2F78EJKf6rUSKv4PwAmpyEnTGfd5jItA",
  "d": "NUvs3P54TNwgR2E3Fyx9seQMpXnzatk8c-yle19v5ag"
}

Figure 1: Issuer Private Key (es256)

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

{
  "kty": "EC",
  "crv": "P-256",
  "x": "g2KXbIrYPC52I5WJ15LOP6hVP45Vk0h3boa_P1zfT1s",
  "y": "3if3zLCcYnrBBFPpLJg6Zuhx256id-iEEHGKGu0Veuk",
  "d": "hNe9bqQ647m_j47UtXRkvQcOqTKllqugs3UtPjEA8Nc"
}

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": "unzH-53o7drh9mld3lt2mDpvhwtQX7QAjrRr6uG5OK0",
  "y": "KsBDYp_mQ5wkfx-oeuAEbjN454dK4e_XfDk71Ny6FP0",
  "d": "pdDAcSP_P62zA2HXUdo4rUcqbL9MHwY1q83OlVrHQzA"
}

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.¶

{
  "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": "g2KXbIrYPC52I5WJ15LOP6hVP45Vk0h3boa_P1zfT1s",
    "y": "3if3zLCcYnrBBFPpLJg6Zuhx256id-iEEHGKGu0Veuk",
    "d": "hNe9bqQ647m_j47UtXRkvQcOqTKllqugs3UtPjEA8Nc"
  },
  "presentation_key": {
    "kty": "EC",
    "crv": "P-256",
    "x": "unzH-53o7drh9mld3lt2mDpvhwtQX7QAjrRr6uG5OK0",
    "y": "KsBDYp_mQ5wkfx-oeuAEbjN454dK4e_XfDk71Ny6FP0",
    "d": "pdDAcSP_P62zA2HXUdo4rUcqbL9MHwY1q83OlVrHQzA"
  }
}

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:¶
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Figure 5: Encoded Issuer Protected Header (es256, base64url-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.¶

The resulting JSON serialized JPT using the above examples is:¶

{
  "issuer": "eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
       Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaW
       x5X25hbWUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292
       ZXJfMjEiXSwicHJvb2Zfa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLC
       J4IjoiZzJLWGJJcllQQzUySTVXSjE1TE9QNmhWUDQ1VmswaDNib2FfUDF6ZlQx
       cyIsInkiOiIzaWYzekxDY1luckJCRlBwTEpnNlp1aHgyNTZpZC1pRUVIR0tHdT
       BWZXVrIiwiZCI6ImhOZTlicVE2NDdtX2o0N1V0WFJrdlFjT3FUS2xscXVnczNV
       dFBqRUE4TmMifSwicHJlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydi
       I6IlAtMjU2IiwieCI6InVuekgtNTNvN2RyaDltbGQzbHQybURwdmh3dFFYN1FB
       anJScjZ1RzVPSzAiLCJ5IjoiS3NCRFlwX21RNXdrZngtb2V1QUViak40NTRkSz
       RlX1hmRGs3MU55NkZQMCIsImQiOiJwZERBY1NQX1A2MnpBMkhYVWRvNHJVY3Fi
       TDlNSHdZMXE4M09sVnJIUXpBIn19",
  "payloads": [
    "MTcxNDUyMTYwMA",
    "MTcxNzE5OTk5OQ",
    "IkRvZSI",
    "IkpheSI",
    "ImpheWRvZUBleGFtcGxlLm9yZyI",
    "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
       VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
       kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
       ImNvdW50cnkiOiJVU0EifQ",
    "dHJ1ZQ"
  ],
  "proof": [
    "d-eAYTJo1jnPD4N-v-uyihYgaaU-mjVgg4ddy9h8T5-FOwxtcWstIz18P70mwgdw
       uOKjFnjEKCsodZveIOIbfQ",
    "w83ALg6i8zQgyMV3tl_mWJ3KYFQluLAgqT50lMTubImqyrxW_9EvuqrWvJemTV1m
       c1Du3jYi1TTkS9c8Ssy3fA",
    "H5mwIimFSDUoo53jr0pCu3v4BNNSKy2XQrweRsL0Gj9fhM3EKhOziPIN58JQVW5V
       FSX0ROSBjysbOGYSoXEw2w",
    "YQkRk3pRK5F_ohbCejJI8TiIIyRPD5TWjtMzoPvZhyA6PUQOwJU75eOmRjdSyD8Y
       TrF0F3SkNnnOHA2UFxo05w",
    "vICusMnKwsaRd7zQBZxgvyUx4FVupqGdXDPTh3DQSc3I0B8ZdB4WwuIQsi6gRgQU
       VKyCLuMYpPZTHwrqWXdH2w",
    "vR5d3At6Iag0eG2a2zqAp0hIkazCLLBB3KXB53Duj2Mg77FECyJTKltZnW8ccjSB
       JjyTahV3le5u3BU7jcJN7w",
    "IoKeFllRBJcVHSclcDmgUnJiz4OsB27u1rKuMv2kF54PDLiKfhV90bnf2H0hzqaj
       -EGKQPx-xRiIShMxvTGD2g",
    "QeMrl0bQkFE6qQzahagbyS7DCY382Zf4ROAzbSoeRakE4tIfUOVXmqN_ZSXZ-7y8
       gultyZTzCXw5qEwaC6OrBQ"
  ]
}

Figure 6: Issued JWP in JSON Serialization (es256)

The compact serialization of the same JPT is:¶
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.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRv
ZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duL
CBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG
9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDU
sImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.d-eAYTJo1jnPD4N-v-uyihYgaaU-mjVgg4ddy9
h8T5-FOwxtcWstIz18P70mwgdwuOKjFnjEKCsodZveIOIbfQ~w83ALg6i8zQgyMV3tl_m
WJ3KYFQluLAgqT50lMTubImqyrxW_9EvuqrWvJemTV1mc1Du3jYi1TTkS9c8Ssy3fA~H5
mwIimFSDUoo53jr0pCu3v4BNNSKy2XQrweRsL0Gj9fhM3EKhOziPIN58JQVW5VFSX0ROS
BjysbOGYSoXEw2w~YQkRk3pRK5F_ohbCejJI8TiIIyRPD5TWjtMzoPvZhyA6PUQOwJU75
eOmRjdSyD8YTrF0F3SkNnnOHA2UFxo05w~vICusMnKwsaRd7zQBZxgvyUx4FVupqGdXDP
Th3DQSc3I0B8ZdB4WwuIQsi6gRgQUVKyCLuMYpPZTHwrqWXdH2w~vR5d3At6Iag0eG2a2
zqAp0hIkazCLLBB3KXB53Duj2Mg77FECyJTKltZnW8ccjSBJjyTahV3le5u3BU7jcJN7w
~IoKeFllRBJcVHSclcDmgUnJiz4OsB27u1rKuMv2kF54PDLiKfhV90bnf2H0hzqaj-EGK
QPx-xRiIShMxvTGD2g~QeMrl0bQkFE6qQzahagbyS7DCY382Zf4ROAzbSoeRakE4tIfUO
VXmqN_ZSXZ-7y8gultyZTzCXw5qEwaC6OrBQ

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": "VOFYAMINJnBle9LCkUCQfYus8r4h-vHLHHWRED9c41A"
}

Figure 8: Presentation Header

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

eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJWT0ZZQU1JTkpuQmxlOUxDa1VDUWZZdXM4cjRoLXZITEhIV1JFRD
ljNDFBIn0

Figure 9: Presentation Header (base64url-encoded)

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

9c6U4q83dX31kqxgByb1xmkjqiPXcZ13smGVfmACwKMvrvpN-lRNd8_r-lSoO7baDeo6f
pwb-L6xUqdH2uEYAw

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:¶

{
  "presentation": "eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaX
       BpZW50LmV4YW1wbGUuY29tIiwibm9uY2UiOiJWT0ZZQU1JTkpuQmxlOUxDa1VD
       UWZZdXM4cjRoLXZITEhIV1JFRDljNDFBIn0",
  "issuer": "eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
       Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaW
       x5X25hbWUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292
       ZXJfMjEiXSwicHJvb2Zfa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLC
       J4IjoiZzJLWGJJcllQQzUySTVXSjE1TE9QNmhWUDQ1VmswaDNib2FfUDF6ZlQx
       cyIsInkiOiIzaWYzekxDY1luckJCRlBwTEpnNlp1aHgyNTZpZC1pRUVIR0tHdT
       BWZXVrIiwiZCI6ImhOZTlicVE2NDdtX2o0N1V0WFJrdlFjT3FUS2xscXVnczNV
       dFBqRUE4TmMifSwicHJlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydi
       I6IlAtMjU2IiwieCI6InVuekgtNTNvN2RyaDltbGQzbHQybURwdmh3dFFYN1FB
       anJScjZ1RzVPSzAiLCJ5IjoiS3NCRFlwX21RNXdrZngtb2V1QUViak40NTRkSz
       RlX1hmRGs3MU55NkZQMCIsImQiOiJwZERBY1NQX1A2MnpBMkhYVWRvNHJVY3Fi
       TDlNSHdZMXE4M09sVnJIUXpBIn19",
  "payloads": [
    "MTcxNDUyMTYwMA",
    "MTcxNzE5OTk5OQ",
    "IkRvZSI",
    "IkpheSI",
    "ImpheWRvZUBleGFtcGxlLm9yZyI",
    "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
       VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
       kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
       ImNvdW50cnkiOiJVU0EifQ",
    "dHJ1ZQ",
    null,
    null
  ],
  "proof": [
    "d-eAYTJo1jnPD4N-v-uyihYgaaU-mjVgg4ddy9h8T5-FOwxtcWstIz18P70mwgdw
       uOKjFnjEKCsodZveIOIbfQ",
    "9c6U4q83dX31kqxgByb1xmkjqiPXcZ13smGVfmACwKMvrvpN-lRNd8_r-lSoO7ba
       Deo6fpwb-L6xUqdH2uEYAw",
    "w83ALg6i8zQgyMV3tl_mWJ3KYFQluLAgqT50lMTubImqyrxW_9EvuqrWvJemTV1m
       c1Du3jYi1TTkS9c8Ssy3fA",
    "H5mwIimFSDUoo53jr0pCu3v4BNNSKy2XQrweRsL0Gj9fhM3EKhOziPIN58JQVW5V
       FSX0ROSBjysbOGYSoXEw2w",
    "YQkRk3pRK5F_ohbCejJI8TiIIyRPD5TWjtMzoPvZhyA6PUQOwJU75eOmRjdSyD8Y
       TrF0F3SkNnnOHA2UFxo05w",
    "vICusMnKwsaRd7zQBZxgvyUx4FVupqGdXDPTh3DQSc3I0B8ZdB4WwuIQsi6gRgQU
       VKyCLuMYpPZTHwrqWXdH2w",
    "vR5d3At6Iag0eG2a2zqAp0hIkazCLLBB3KXB53Duj2Mg77FECyJTKltZnW8ccjSB
       JjyTahV3le5u3BU7jcJN7w"
  ]
}

Figure: Final Presentation in JSON Serialization¶

And also in compact serialization:¶

eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJWT0ZZQU1JTkpuQmxlOUxDa1VDUWZZdXM4cjRoLXZITEhIV1JFRD
ljNDFBIn0.eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8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.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheS
I~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5
Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4g
U3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZ
SI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ~~.d-eAYTJo1jnPD4N-v-uyihYgaa
U-mjVgg4ddy9h8T5-FOwxtcWstIz18P70mwgdwuOKjFnjEKCsodZveIOIbfQ~9c6U4q83
dX31kqxgByb1xmkjqiPXcZ13smGVfmACwKMvrvpN-lRNd8_r-lSoO7baDeo6fpwb-L6xU
qdH2uEYAw~w83ALg6i8zQgyMV3tl_mWJ3KYFQluLAgqT50lMTubImqyrxW_9EvuqrWvJe
mTV1mc1Du3jYi1TTkS9c8Ssy3fA~H5mwIimFSDUoo53jr0pCu3v4BNNSKy2XQrweRsL0G
j9fhM3EKhOziPIN58JQVW5VFSX0ROSBjysbOGYSoXEw2w~YQkRk3pRK5F_ohbCejJI8Ti
IIyRPD5TWjtMzoPvZhyA6PUQOwJU75eOmRjdSyD8YTrF0F3SkNnnOHA2UFxo05w~vICus
MnKwsaRd7zQBZxgvyUx4FVupqGdXDPTh3DQSc3I0B8ZdB4WwuIQsi6gRgQUVKyCLuMYpP
ZTHwrqWXdH2w~vR5d3At6Iag0eG2a2zqAp0hIkazCLLBB3KXB53Duj2Mg77FECyJTKltZ
nW8ccjSBJjyTahV3le5u3BU7jcJN7w

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:¶

{
  "kty": "EC2",
  "alg": "BBS",
  "use": "proof",
  "crv": "BLS12381G2",
  "x": "AuT8_mUzlzoNE20eDDrekSNgOLjOqw2vuDAibs8RWY1I_A3NB6LfnrwvlqP0Y
       f6DDzjjOG29JLEccyHgJSUMa-r_BS1gMzcCjox3adtmhet-9sGNBdupJeLwNuW
       dESyJ",
  "y": "FCQ4ubUHnZVkVs4yPueCBzbKGKvyDK_iaQLP7oce0FX1j92SSo-yJbzuXpORh
       tyFEZZ-Kvy30_i2I91lyd97Y-x2On2pQUrxcAhfx2Y8GnmKX2CEHwMCIUbm3Rp
       sx47v",
  "d": "KaNjIWeOc4RG1uHm-xl-ET6ogF9c4BJdYQvCo6w08No"
}

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:¶

{
  "issuer": "eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRu
       RXhSMERValU4IiwiYWxnIjoiQkJTIn0",
  "payloads": [
    "MTcxNDUyMTYwMA",
    "MTcxNzE5OTk5OQ",
    "IkRvZSI",
    "IkpheSI",
    "ImpheWRvZUBleGFtcGxlLm9yZyI",
    "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
       VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
       kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
       ImNvdW50cnkiOiJVU0EifQ",
    "dHJ1ZQ"
  ],
  "proof": [
    "hd6qXoswL7hAGRbibein4_s6A_TmRDh9yIkjKyfW9tK0GXoqN9S6aMh5qTds47Gc
       JkpMVbgHxLGohNzlL9S7ZGFSIJAZDd_aYXH-Mr6peCg"
  ]
}

Figure 13: Issued JWP (JSON serialization)

eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRuRXhSMERValU4I
iwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~Imph
eWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b
3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIi
wibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTI
zNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.hd6qXoswL7hAGRbibein4_s6A_TmRDh9yI
kjKyfW9tK0GXoqN9S6aMh5qTds47GcJkpMVbgHxLGohNzlL9S7ZGFSIJAZDd_aYXH-Mr6
peCg

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:¶

{
  "presentation": "eyJhbGciOiJCQlMiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC
       5leGFtcGxlLmNvbSIsIm5vbmNlIjoid3JtQlJrS3RYalEifQ",
  "issuer": "eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRu
       RXhSMERValU4IiwiYWxnIjoiQkJTIn0",
  "payloads": [
    "MTcxNDUyMTYwMA",
    "MTcxNzE5OTk5OQ",
    "IkRvZSI",
    "IkpheSI",
    null,
    null,
    null
  ],
  "proof": [
    "iY1vpokISeH5ucw5hDU02zB3gOxBtkwi3Yuwsm45ppwOyEutajRAIj21vzONp09p
       ib1irzoM3ZByPSmrLmh-47bCndG9GXukBBTYazD8LCRSLYX6jeto59Il2VJxkg
       hQh2pRgJMuksEzgudO8OyMWBeHj8KrKMhTnvUW-2mj6aHHoAEIJwBx2LLHTZpN
       Rs7gS0omW4JDwSh3vQOuoLbEQQGrL573NF-eMQ8f0beH6yJW0y53zW1HBBw686
       rqfiFC8BH-6zvki16Lr1GtRyZc2T76UAMr1WA-Yukd0g4c8JyiORDh7FmF47dI
       xMf2AAcwE4ZrHmm0NV__BtLF1KWCTopxkOre9lzNyVPXgcAnYbxSkdYazFVscl
       QQjN4E587ImuF0qlQvzwvCxMiZXthS_kIKDi80XzoNzOmB6UKjX-eklEXjAN2C
       H7GZdIbpRtvyELNk-gImb75dHaztdLEncGgt9htkTQIqBvo7Z2Dfl3g"
  ]
}

Figure 16: Presentation JWP (JSON serialization)

eyJhbGciOiJCQlMiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC5leGFtcGxlLmNvbSIsI
m5vbmNlIjoid3JtQlJrS3RYalEifQ.eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJ
UOVJiYm5yb2JwdGRuRXhSMERValU4IiwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxN
zE5OTk5OQ~IkRvZSI~IkpheSI~~~.iY1vpokISeH5ucw5hDU02zB3gOxBtkwi3Yuwsm45
ppwOyEutajRAIj21vzONp09pib1irzoM3ZByPSmrLmh-47bCndG9GXukBBTYazD8LCRSL
YX6jeto59Il2VJxkghQh2pRgJMuksEzgudO8OyMWBeHj8KrKMhTnvUW-2mj6aHHoAEIJw
Bx2LLHTZpNRs7gS0omW4JDwSh3vQOuoLbEQQGrL573NF-eMQ8f0beH6yJW0y53zW1HBBw
686rqfiFC8BH-6zvki16Lr1GtRyZc2T76UAMr1WA-Yukd0g4c8JyiORDh7FmF47dIxMf2
AAcwE4ZrHmm0NV__BtLF1KWCTopxkOre9lzNyVPXgcAnYbxSkdYazFVsclQQjN4E587Im
uF0qlQvzwvCxMiZXthS_kIKDi80XzoNzOmB6UKjX-eklEXjAN2CH7GZdIbpRtvyELNk-g
Imb75dHaztdLEncGgt9htkTQIqBvo7Z2Dfl3g

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:¶

{
  "kty": "EC",
  "crv": "P-256",
  "x": "V3cpRRv0e44j0E2BU6l9oHJnl7HIpx41PlgjKC2YSNA",
  "y": "4A6HnHEDNGM2F78EJKf6rUSKv4PwAmpyEnTGfd5jItA",
  "d": "NUvs3P54TNwgR2E3Fyx9seQMpXnzatk8c-yle19v5ag"
}

Figure 18: Issuer private key

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

"QhOnOP0E60GLqiOugBW-o6YyAlqWwMXzjQdNZOcnoP0"

Figure 19: Shared Secret

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

{
  "kty": "EC",
  "crv": "P-256",
  "x": "unzH-53o7drh9mld3lt2mDpvhwtQX7QAjrRr6uG5OK0",
  "y": "KsBDYp_mQ5wkfx-oeuAEbjN454dK4e_XfDk71Ny6FP0",
  "d": "pdDAcSP_P62zA2HXUdo4rUcqbL9MHwY1q83OlVrHQzA"
}

Figure 20: 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": "unzH-53o7drh9mld3lt2mDpvhwtQX7QAjrRr6uG5OK0",
    "y": "KsBDYp_mQ5wkfx-oeuAEbjN454dK4e_XfDk71Ny6FP0"
  }
}

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:¶

WNtKTmGCcQPLwihuFbbB6EhEyqhMIu049s11wfSFNiw

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:¶

[
  "_H2L_-b4Y2QedjTlSfq_uVsVGEzQx-Jx2xUdUZq281Y",
  "1DeAYUa80nVBf4DCUTvqz1IMtZ1EOv2Z8FB7axMggJc",
  "XvMC_mZpIw7_HuMuUTgP2JfkcCP85ClQw5grT2uMBM8",
  "WSO4VvwrErA0ljNgbgKpOkiO1wcqq5xbWjZZt8e1V44",
  "edGz5BhIVkvzIZK1nKpAPwZm9FI7CMBjujq4tFU8tDs",
  "3YScVRepcpJU4t-ytYeFT9obrPJQMoW22IoXz9Hy9d8",
  "MGQQrgFrMxSBzVQToSsg8Udv0JKCwGPZsIWqHoFy0vw"
]

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:¶

[
  "qGPC5C_JVHxMudI2ed5FKidNYjdb2IEzE-pUOvLwTDc",
  "6IeHKfwtVN7__G6-VyyjYLgAvXKqhE6gxuuuILsXT7g",
  "DYe0BErVeYNL9qY43tHabO2mpwuvnNBvYlNTyTn3VSw",
  "uzsOodxNO_l1gjFUqQhhdvskI-zgMzbQIaoORXCt8-Y",
  "BI-ayaItFb2x3DW2zesurTNCYNSKb1myjIjLiVQZk7k",
  "_-onNWuuR8eDkJMIXs-gMv09n8uxxuA9_RkuFRM2Lwg",
  "qFXyATI4iysSffX7Id3Di500plpNk2GZUj4bYlveyaA"
]

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.¶

[
  "brZ7cnHKZt1k802O2FqPAaWYN9JG3ey6OalnG7wWk1Y4XKQVwFsyoEaqoVYHyJV7J9
YNpmstM4EJTYT_GyQifw",
  "WP5Rhe3IOGigzjG9RSbWwbX1WuPTUXqvlSqooCUr3OI"
]

Figure 26: Issued Proof (base64url-encoded)

The final issued JWP in JSON serialization is:¶

{
  "issuer": "eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hb
WUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicH
Jlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2l
nbiIsIngiOiJ1bnpILTUzbzdkcmg5bWxkM2x0Mm1EcHZod3RRWDdRQWpyUnI2dUc1T0sw
IiwieSI6IktzQkRZcF9tUTV3a2Z4LW9ldUFFYmpONDU0ZEs0ZV9YZkRrNzFOeTZGUDAif
X0",
  "payloads": [
    "MTcxNDUyMTYwMA",
    "MTcxNzE5OTk5OQ",
    "IkRvZSI",
    "IkpheSI",
    "ImpheWRvZUBleGFtcGxlLm9yZyI",
    "eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBb
nl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOi
JVU0EifQ",
    "dHJ1ZQ"
  ],
  "proof": [
    "brZ7cnHKZt1k802O2FqPAaWYN9JG3ey6OalnG7wWk1Y4XKQVwFsyoEaqoVYHyJV7
J9YNpmstM4EJTYT_GyQifw",
    "WP5Rhe3IOGigzjG9RSbWwbX1WuPTUXqvlSqooCUr3OI"
  ]
}

Figure 27: Issued JWP (in JSON serialization)

The same JWP in compact serialization:¶

eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL
mV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUiLCJnaXZlbl
9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJlc2VudGF0aW9
uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2lnbiIsIngiOiJ1
bnpILTUzbzdkcmg5bWxkM2x0Mm1EcHZod3RRWDdRQWpyUnI2dUc1T0swIiwieSI6IktzQ
kRZcF9tUTV3a2Z4LW9ldUFFYmpONDU0ZEs0ZV9YZkRrNzFOeTZGUDAifX0.MTcxNDUyMT
YwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb
3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3
RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiw
icmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~d
HJ1ZQ.brZ7cnHKZt1k802O2FqPAaWYN9JG3ey6OalnG7wWk1Y4XKQVwFsyoEaqoVYHyJV
7J9YNpmstM4EJTYT_GyQifw~WP5Rhe3IOGigzjG9RSbWwbX1WuPTUXqvlSqooCUr3OI

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": "VOFYAMINJnBle9LCkUCQfYus8r4h-vHLHHWRED9c41A"
}

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:¶

[
  "ttaRQXiYH5HTFZPkhlQCKbd_C7AGA_s8dVDiq7PknL2RwO-yyBy9KzAVOOMyMtMldQ
6gMREZqIPZbwhKynrCCg",
  "brZ7cnHKZt1k802O2FqPAaWYN9JG3ey6OalnG7wWk1Y4XKQVwFsyoEaqoVYHyJV7J9
YNpmstM4EJTYT_GyQifw",
  "_H2L_-b4Y2QedjTlSfq_uVsVGEzQx-Jx2xUdUZq281Y",
  "1DeAYUa80nVBf4DCUTvqz1IMtZ1EOv2Z8FB7axMggJc",
  "XvMC_mZpIw7_HuMuUTgP2JfkcCP85ClQw5grT2uMBM8",
  "WSO4VvwrErA0ljNgbgKpOkiO1wcqq5xbWjZZt8e1V44",
  "BI-ayaItFb2x3DW2zesurTNCYNSKb1myjIjLiVQZk7k",
  "_-onNWuuR8eDkJMIXs-gMv09n8uxxuA9_RkuFRM2Lwg",
  "qFXyATI4iysSffX7Id3Di500plpNk2GZUj4bYlveyaA"
]

Figure 30: Presentation proof (base64url-encoded)

The final presented JWP in JSON serialization is:¶

{
  "presentation": "eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaX
BpZW50LmV4YW1wbGUuY29tIiwibm9uY2UiOiJWT0ZZQU1JTkpuQmxlOUxDa1VDUWZZdXM
4cjRoLXZITEhIV1JFRDljNDFBIn0",
  "issuer": "eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hb
WUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicH
Jlc2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2l
nbiIsIngiOiJ1bnpILTUzbzdkcmg5bWxkM2x0Mm1EcHZod3RRWDdRQWpyUnI2dUc1T0sw
IiwieSI6IktzQkRZcF9tUTV3a2Z4LW9ldUFFYmpONDU0ZEs0ZV9YZkRrNzFOeTZGUDAif
X0",
  "payloads": [
    "MTcxNDUyMTYwMA",
    "MTcxNzE5OTk5OQ",
    "IkRvZSI",
    "IkpheSI",
    null,
    null,
    null
  ],
  "proof": [
    "ttaRQXiYH5HTFZPkhlQCKbd_C7AGA_s8dVDiq7PknL2RwO-yyBy9KzAVOOMyMtMl
dQ6gMREZqIPZbwhKynrCCg",
    "brZ7cnHKZt1k802O2FqPAaWYN9JG3ey6OalnG7wWk1Y4XKQVwFsyoEaqoVYHyJV7
J9YNpmstM4EJTYT_GyQifw",
    "_H2L_-b4Y2QedjTlSfq_uVsVGEzQx-Jx2xUdUZq281Y",
    "1DeAYUa80nVBf4DCUTvqz1IMtZ1EOv2Z8FB7axMggJc",
    "XvMC_mZpIw7_HuMuUTgP2JfkcCP85ClQw5grT2uMBM8",
    "WSO4VvwrErA0ljNgbgKpOkiO1wcqq5xbWjZZt8e1V44",
    "BI-ayaItFb2x3DW2zesurTNCYNSKb1myjIjLiVQZk7k",
    "_-onNWuuR8eDkJMIXs-gMv09n8uxxuA9_RkuFRM2Lwg",
    "qFXyATI4iysSffX7Id3Di500plpNk2GZUj4bYlveyaA"
  ]
}

Figure 31: Presented JWP (in JSON serialization)

The same JWP in compact serialization:¶

eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJWT0ZZQU1JTkpuQmxlOUxDa1VDUWZZdXM4cjRoLXZITEhIV1JFRD
ljNDFBIn0.eyJhbGciOiJNQUMtSDI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUi
LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJlc
2VudGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwidXNlIjoic2lnbi
IsIngiOiJ1bnpILTUzbzdkcmg5bWxkM2x0Mm1EcHZod3RRWDdRQWpyUnI2dUc1T0swIiw
ieSI6IktzQkRZcF9tUTV3a2Z4LW9ldUFFYmpONDU0ZEs0ZV9YZkRrNzFOeTZGUDAifX0.
MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.ttaRQXiYH5HTFZPkhlQC
Kbd_C7AGA_s8dVDiq7PknL2RwO-yyBy9KzAVOOMyMtMldQ6gMREZqIPZbwhKynrCCg~br
Z7cnHKZt1k802O2FqPAaWYN9JG3ey6OalnG7wWk1Y4XKQVwFsyoEaqoVYHyJV7J9YNpms
tM4EJTYT_GyQifw~_H2L_-b4Y2QedjTlSfq_uVsVGEzQx-Jx2xUdUZq281Y~1DeAYUa80
nVBf4DCUTvqz1IMtZ1EOv2Z8FB7axMggJc~XvMC_mZpIw7_HuMuUTgP2JfkcCP85ClQw5
grT2uMBM8~WSO4VvwrErA0ljNgbgKpOkiO1wcqq5xbWjZZt8e1V44~BI-ayaItFb2x3DW
2zesurTNCYNSKb1myjIjLiVQZk7k~_-onNWuuR8eDkJMIXs-gMv09n8uxxuA9_RkuFRM2
Lwg~qFXyATI4iysSffX7Id3Di500plpNk2GZUj4bYlveyaA

Figure 32: Presented JWP (in compact serialization)