JSON Proof Algorithms

Internet-Draft	json-proof-algorithms	July 2025
Jones, et al.	Expires 8 January 2026	[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 uses multiple signing keys to protect the protected header as well as individual payloads of an Issued JWP. The issuer uses a stable public key to sign each protected header, and a per-JWP ephemeral key (conveyed within the protected header) to protect the individual payloads. These signatures are all created using the same Asymmetric Algorithm, with the JOSE and COSE name/label of this algorithm being part of registration for a fully-specified Single Use algorithm identifier.¶

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

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

6.1.2. Holder Setup

In order to support the protection of a presentation by a holder to a verifier, the holder MUST use a 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.¶

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

6.1.3. Issuer Setup

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

6.1.4. Signing Payloads

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

6.1.5. Issuer Protected Header

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

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

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

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

6.1.6. Payloads

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

6.1.7. Proof

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

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

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

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

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

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

6.1.9. Presentation

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

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

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

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

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

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

The issuer's signature over the issuer protected header¶
The payload signature corresponding to the second payload¶
The payload signature corresponding to the fifth payload.¶

The presentation internal representation would be calculated with these three proof components, while the final presentation would have an additional 4th component containing the signature using the holder's private key.¶

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

6.1.10. Verification of Presentation

Verification is performed using the following steps.¶

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

6.1.11. JPA Registration

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

6.2. Presentation Internal Representation

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

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

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

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

0x84 5B¶
The length and octets of the presentation protected header¶
0x5B¶
The length and octets of the issuer protected header¶
0x9B¶
The number of payload slots in the issued message¶
For each payload representation:¶
- If the payload is being ommitted, the value 0xF6¶
- Otherwise:¶
  1. 0x5B¶
  2. The length and octets of the payload¶
0x9B¶
The number of proof components as specified by the algorithm¶
For each proof component, append:¶
1. 0x5B¶
2. The length and octets of the proof component¶

6.3. BBS

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

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

6.3.1. JPA Algorithms

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

6.3.2. Key Format

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

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

6.3.3. Issuance

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

6.3.4. 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.¶

6.3.5. Presentation

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

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

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

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

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

6.3.6. Presentation Verification

Verification of a presentation is done by the verifier using the ProofVerify operation from Section 3.5.4.¶

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

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

6.4. Message Authentication Code

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

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

Like the 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.¶

6.4.1. 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.¶

6.4.2. Issuer Setup

To use the MAC algorithm, the issuer must have a stable public key pair to perform signing. To start the issuance process, a single 32-byte random Shared Secret must first be generated. This value will be shared privately 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.¶

6.4.3. Combined MAC Representation

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

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

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

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

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

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

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

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

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

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

6.4.4. Issuer Protected Header

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

6.4.5. Issuer Proof

The issuer proof consists of two octet strings.¶

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

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

6.4.6. Presentation Protected Header

See the Presentation Protected Header section given for Single Use algorithms.¶

6.4.7. Presentation Proof

The presentation proof is made of multiple components.¶

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

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

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

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

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

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

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

6.4.8. Verification of the Presentation Proof

Verification is performed using the following steps.¶

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

6.4.9. JPA Registration

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

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

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 6.3.1 of this specification¶
Algorithm Analysis Documents(s): n/a¶

8.1.2.5. MAC-H256 Algorithm

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

8.1.2.6. MAC-H384 Algorithm

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

8.1.2.7. MAC-H512 Algorithm

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

8.1.2.8. MAC-K25519 Algorithm

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

8.1.2.9. MAC-K448 Algorithm

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

8.1.2.10. MAC-H256K Algorithm

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

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": "LmADmWZgOf8maoNN_YQVRAKPeBafKuPVe3w4cIquSZ0",
  "y": "ZVVkSFOJvgZipgPCrYmsOZJ0t2Q-QXh4omOzCPXpuWY",
  "d": "KfgeQCNRFDLozldtV-RqlJa-iDFmjLnoKW_Ib3VK15I"
}

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": "GN6dq-WDoVo9PA1GUrYXMsDQS-nUKjwtp-7sGsiUpuI",
  "y": "8XfSfsYb_FzTreaGM2J6z1vKAHeS-HY0Ia88-slh51o",
  "d": "RvVeBXqo4M3IQXsctBn8iuTUh7hMF8BFb5c-DmzrOlI"
}

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": "EkX-Cxc_riJfMIv7j_07rNG6uRX6FCnpezn4iZBu9Dw",
  "y": "eGMYiNrKu9fKv6k1BfNPSQJ3Lp9bWmXotbVuCwG8MYc",
  "d": "jDYFOLZky4nU6CAkGDq6kow2JeLF3-ReFdGAqLCTC6Q"
}

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",
  "hpa": "ES256",
  "claims": [
    "iat",
    "exp",
    "family_name",
    "given_name",
    "email",
    "address",
    "age_over_21"
  ],
  "proof_key": {
    "kty": "EC",
    "crv": "P-256",
    "x": "GN6dq-WDoVo9PA1GUrYXMsDQS-nUKjwtp-7sGsiUpuI",
    "y": "8XfSfsYb_FzTreaGM2J6z1vKAHeS-HY0Ia88-slh51o"
  },
  "presentation_key": {
    "kty": "EC",
    "crv": "P-256",
    "x": "EkX-Cxc_riJfMIv7j_07rNG6uRX6FCnpezn4iZBu9Dw",
    "y": "eGMYiNrKu9fKv6k1BfNPSQJ3Lp9bWmXotbVuCwG8MYc"
  }
}

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~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0I
E1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOi
IxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJ
wb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.PWvT-r5tZm_zvA
E8OSV3pw1uq487uAhHTL-pp5JbAGODNts-YhxTkuK4ACQHkxJxFLHMFIo4MmeVIx1Kdyc
inQ~aMQWuzQcMciC2xSFBAYhrZEOdYH8_2VWZeTWzW2wRaeg9m8dNOq60WNO3Uv4vq8is
fUoY7VDnLVZ8w7lN4J1hQ~o2X1fktRsjOmgCZKEZc7wcn7QHIvSq0wExdeIYbaBJwtpwR
ZWBlejWlnA29XCIlqfsaSYJkV43Xhx5Stf2NWsg~73BkvpGMN_Q-EqPqYLMcO8gFDN3xq
kJLKcZ4LpoZ3UfwsjsthET3VFPGYjguAoR1_1SHgvxjqz2D3HqiqbhbVQ~BzZj2sCug-v
kQROSYmO4XBiSlZIbY3P-f9kU5goqHLlkABqsGoXcchHdL1Ab_yC6oJEPWcMuubMGpOZ5
8YhGSQ~VvHxSIETRCs8BOJwUAgf51SfQg0QE2CqX1l_VCWPXNPG5lXHxXi0JonkA_4my6
API2mInb7OnZs8n8niFmT1Gw~wDkZvdWgNvYlcr5UIJCRoSvtPTWKiZuM32T_VQA2LA9M
5dmokxEfQB-mBGPJyx8aGuhC-nmOmrPqFDLk3K5G7g~rZTU4njxZdcVAp0rIdvlcsd0wC
wUmk1eoiOtimzXHH-I9cA9wvfydcb_ZSJl9YpNL25Fhg1kqzMzdAsXXr7IvQ

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": "IzLqrQVM9yrSBup5bfo6kqmpkEJje_7-9xaEA6XQwe0"
}

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

eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJJekxxclFWTTl5clNCdXA1YmZvNmtxbXBrRUpqZV83LTl4YUVBNl
hRd2UwIn0

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

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

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

eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJJekxxclFWTTl5clNCdXA1YmZvNmtxbXBrRUpqZV83LTl4YUVBNl
hRd2UwIn0.eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8
vaXNzdWVyLmV4YW1wbGUiLCJocGEiOiJFUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAi
LCJmYW1pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb
3Zlcl8yMSJdLCJwcm9vZl9rZXkiOnsia3R5IjoiRUMiLCJjcnYiOiJQLTI1NiIsIngiOi
JHTjZkcS1XRG9WbzlQQTFHVXJZWE1zRFFTLW5VS2p3dHAtN3NHc2lVcHVJIiwieSI6Ijh
YZlNmc1liX0Z6VHJlYUdNMko2ejF2S0FIZVMtSFkwSWE4OC1zbGg1MW8ifSwicHJlc2Vu
dGF0aW9uX2tleSI6eyJrdHkiOiJFQyIsImNydiI6IlAtMjU2IiwieCI6IkVrWC1DeGNfc
mlKZk1JdjdqXzA3ck5HNnVSWDZGQ25wZXpuNGlaQnU5RHciLCJ5IjoiZUdNWWlOckt1OW
ZLdjZrMUJmTlBTUUozTHA5YldtWG90YlZ1Q3dHOE1ZYyJ9fQ.MTcxNDUyMTYwMA~MTcxN
zE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQ
iOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2Fk
ZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uI
joiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ~~.PW
vT-r5tZm_zvAE8OSV3pw1uq487uAhHTL-pp5JbAGODNts-YhxTkuK4ACQHkxJxFLHMFIo
4MmeVIx1KdycinQ~aMQWuzQcMciC2xSFBAYhrZEOdYH8_2VWZeTWzW2wRaeg9m8dNOq60
WNO3Uv4vq8isfUoY7VDnLVZ8w7lN4J1hQ~o2X1fktRsjOmgCZKEZc7wcn7QHIvSq0wExd
eIYbaBJwtpwRZWBlejWlnA29XCIlqfsaSYJkV43Xhx5Stf2NWsg~73BkvpGMN_Q-EqPqY
LMcO8gFDN3xqkJLKcZ4LpoZ3UfwsjsthET3VFPGYjguAoR1_1SHgvxjqz2D3HqiqbhbVQ
~BzZj2sCug-vkQROSYmO4XBiSlZIbY3P-f9kU5goqHLlkABqsGoXcchHdL1Ab_yC6oJEP
WcMuubMGpOZ58YhGSQ~VvHxSIETRCs8BOJwUAgf51SfQg0QE2CqX1l_VCWPXNPG5lXHxX
i0JonkA_4my6API2mInb7OnZs8n8niFmT1Gw~DQvNVhLfLoXHOoFtmLBb9iITWavBeogl
XmJKDoSVnUs6JGK0qDBUZiMr4nBDdLO4BGsZl9merq3_XDh5CdfBRg

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'1245fe0b173fae225f308bfb8ffd3bacd1bab915fa1429e97b39f889' +
        h'906ef43c', / x /
    -3: h'78631888dacabbd7cabfa93505f34f4902772e9f5b5a65e8b5b56e0b' +
        h'01bc3187'  / y /
  },
  9: {      / presentation key /
    1: 2,   / kty: "EC2" /
    -1: 1,  / crv: "P-256" /
    -2: h'18de9dabe583a15a3d3c0d4652b61732c0d04be9d42a3c2da7eeec1a' +
        h'c894a6e2', / x /
    -3: h'f177d27ec61bfc5cd3ade68633627acf5bca007792f8763421af3cfa' +
        h'c961e75a'  / y /
  },
  10: -9    / hpa: "ESP256" (I-D.ietf-jose-fully-specified-algorithms TBD-9) /
}

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'2332eaad054cf72ad206ea796dfa3a92a9a99042637bfefef7168403a5d0c1ed', / 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
6c652e636f6d0758202332eaad054cf72ad206ea796dfa3a92a9a99042637bfe
fef7168403a5d0c1ed58cfa701010314057668747470733a2f2f697373756572
2e6578616d706c650687060418aa18ab18b318bb6b6167655f6f7665725f3231
08a4010220012158201245fe0b173fae225f308bfb8ffd3bacd1bab915fa1429
e97b39f889906ef43c22582078631888dacabbd7cabfa93505f34f4902772e9f
5b5a65e8b5b56e0b01bc318709a40102200121582018de9dabe583a15a3d3c0d
4652b61732c0d04be9d42a3c2da7eeec1ac894a6e2225820f177d27ec61bfc5c
d3ade68633627acf5bca007792f8763421af3cfac961e75a0a28891a0a382700
1a0a3c3d3f63446f65634a6179726a6179646f65406578616d706c652e6f7267
a601782331323334204d61696e2053742e0a416e79746f776e2c204341203132
3334350a555341026d31323334204d61696e2053742e0367416e79746f776e04
624341056539303231300663555341f5f6f6875840004fab271e0961f2508341
3f0fb3de2551a006d7e2a67c47abbc4cee315aed2eba18ffaa4ad7275f5dfdda
6c9983dcbbe8222e0bcfb32e47b5592213c466c41158405e7db3df91649c31bb
fbe03d8e1b22b6cd0a35ab1a8cc2c1b5774397627d239244ad680c64258efe99
df4a3125a684e2955aa5edf69a93ac465f565c36d835de58401092a50b84eea1
d5488bd2e9537eca179c9ffa9990cbabac58aa2b8c076fd9128983fb267bd593
4334782bdfe195d6d9caa618a3477d01c663de9530bd322a8c58406db67036a8
1c2f111606b3508698567dc857550be4aa3c7cae016865c5aeeb9203909adf5c
aa773513121c0146e8ecee0401d9bfef27dee8c3de4a259fc20fc658405fd136
738272b57ec57a0624bdb6938359da2366a6babf0ffbf8e6818e2c2b5fb47afc
9165b1c15cc3e802a7c8510fca98b729085312b5d0c9238d61154e5d9e58405a
81e1d3f89ad4c872f88072560c286828a996066c4271d52c278c1b6e3e19fbd4
802582d57dea90f148315267285e678da2a7eb1e2cf09d657c0d2dfef5c85f58
40f8ee4ace4469a98c17d21e9a4421043bb033a1c09ebee4784019f70f76dd35
a176715ac6c6c4cad0e2be14db877c2827e4f498373dbd1d05c3688bb8fcea18
cc

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": "B661nl3iuEmKuy3ZcLK2veYfaYdgXk4YwoS9kRz2lwiu3zfwOMdSlgVhteAUn
       F9KGRSAdsq_gLmPUPnAsnfOfcmlL8CXJLv9T8du3HTvfaUEGsLJHvkyYvkTDDy
       2iia7",
  "y": "B9LdhWtFb--J72bzFg5aLTLq42ewWkzUaFISjTKBBvCc8Nx65Z0QwN4V668AJ
       FdGFCNh7-sdDBzsLudA85-rvHnaE3okeJpbyMkbEXBj_jO-tTpTwxzJhX3nVOb
       vll8C",
  "d": "P31QamLQtm-nVMneL7ANUKtyAEkx1DxE3ScdzHjK9cA"
}

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.sj9hr-U8TPH21jQnnxVtXkjfHtCIkQos99
TgjtS8dPB9baeYkHnxm6w0UxhPvXM9NKM9x2mKR9lTlDWx7lyBtWPSTZ30mIKbEGrh2ia
CNW0

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~~~.iaRNJVB4Cn_VzQRKJ2F7EMRF5f8XbrB6ROTysDnc
L-6pS7KoPXAfFEHc7lKOtZNLoMmE6VU3BOs5hGWEpzmiKvcAUH1-Gq1ajLKX5O_H5qLqG
mz67gQMYOiC1Xb886hMksAMQKtkjnd8hKvLmP4tHQy-HTG97Wyd8QKtfOFkkukR5hnM3L
0J4pKUpvX6W_zOOFKdee6GFELokiwwEu70Rxcrguvi7oTeFJpeco6wqZoEXbL3mZH-fGK
aF3uOCwBvFJjA6rdCHwiHzzzty9j_HHC4J0UT8UMNwpv7xP-7IjXCsZ1hdYgx4Mjq-5_i
51I4Pq7g2kGPHYPRal-OSQ9kEf1kmekjcU6IncNjdKKnnFAO_G41sCiOXUmdM8mww6d0P
wyxpXFo2b4wEV6JzHoYwSkE0OWYgNZIUflXd1j-eSN-YGGn95___OR39ngGJ2uKJFCIlU
JpFNekpttX26zxapVNCmtOryCu_OUWUGOZCe4

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": "LmADmWZgOf8maoNN_YQVRAKPeBafKuPVe3w4cIquSZ0",
  "y": "ZVVkSFOJvgZipgPCrYmsOZJ0t2Q-QXh4omOzCPXpuWY",
  "d": "KfgeQCNRFDLozldtV-RqlJa-iDFmjLnoKW_Ib3VK15I"
}

Figure 15: Issuer private key

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

"QX5cnAdXS0H1kalISBlQ_9PCNA__6yrLor5uKQafMa0"

Figure 16: Shared Secret

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

{
  "kty": "EC",
  "crv": "P-256",
  "x": "EkX-Cxc_riJfMIv7j_07rNG6uRX6FCnpezn4iZBu9Dw",
  "y": "eGMYiNrKu9fKv6k1BfNPSQJ3Lp9bWmXotbVuCwG8MYc",
  "d": "jDYFOLZky4nU6CAkGDq6kow2JeLF3-ReFdGAqLCTC6Q"
}

Figure 17: Holder private key

For the following protected header and array of payloads:¶

{
  "alg": "MAC-H256",
  "hpa": "ES256",
  "typ": "JPT",
  "iss": "https://issuer.example",
  "claims": [
    "iat",
    "exp",
    "family_name",
    "given_name",
    "email",
    "address",
    "age_over_21"
  ],
  "presentation_key": {
    "kty": "EC",
    "crv": "P-256",
    "use": "sign",
    "x": "EkX-Cxc_riJfMIv7j_07rNG6uRX6FCnpezn4iZBu9Dw",
    "y": "eGMYiNrKu9fKv6k1BfNPSQJ3Lp9bWmXotbVuCwG8MYc"
  }
}

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

This results in the following set of derived keys:¶

[
  "es3kijhQC4j8J3VFPB5iq155k6FY_1qWAwQk8bWVuR0",
  "r4pLHitd8P21XoD386rDO2TI_pC4hHOf5wtgYjF_0mw",
  "vqhs2s7HLNXszH0G4nHv2r3POiATPe-iLbNzsruLiL4",
  "3EmR33Z1-5422A3bX4vhsdVOSMUadh2s5369is59-PQ",
  "PkSbUEML9tK81Wgj1o7nB3QQy6xvIv8Dl8SNSNhapR0",
  "jZ16aBQFueK3Kq3yrfts9VHqJgpC1j14n01JKIA4oQ0",
  "8GOB-_L6ltveWfPdQiQWKyotVYmudyGyazRGXrDLMVo"
]

Figure 20: Derived payload keys (Base64url-Encoded)

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

[
  "IocpHSpCJ4A86iLuKcBHxsTT_VEi3prPsGMtymtp12c",
  "buNIZePkyxvhVkhE-w-5Ae3z5u258i6loKxLW95eUzQ",
  "fcii9R1nX-u0cMyTJdd8sg6lZUumcMICauCgSkUHCJ4",
  "KZq3T3pmSC4QbYBkWRvuHKbjP7VLiafjo3eleSH9qao",
  "7xeJUlpW1tgXs13Nrkm3-IDJHgDfXzTv07j9i92Tl38",
  "YYnQz9reV1m0oI6kP5yjwSt3IreVluEJ1hXleq4kYpY",
  "qSzTOXw7EL3EbCA-t8JQSE670Z0ku1zjMrdicHajr0A"
]

Figure 21: Payload MAC values (Base64url-Encoded)

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

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

[
  "J2d9Pwt4aeSJe1HPsw7ZV2q9IoPsjIPL_Z0iwn0vaLnK9t4UEBm2MQhmDLQqfOsgHR
Bih2kXs14vl35KifBwkg",
  "viTkELowl0XTNCE1-7XGfrHwoTSqUngT6vaSIifAxJc"
]

Figure 22: Issued Proof (Base64url-Encoded)

The final issued JWP in compact serialization is:¶

eyJhbGciOiJNQUMtSDI1NiIsImhwYSI6IkVTMjU2IiwidHlwIjoiSlBUIiwiaXNzIjoia
HR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbH
lfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJ
dLCJwcmVzZW50YXRpb25fa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ1c2Ui
OiJzaWduIiwieCI6IkVrWC1DeGNfcmlKZk1JdjdqXzA3ck5HNnVSWDZGQ25wZXpuNGlaQ
nU5RHciLCJ5IjoiZUdNWWlOckt1OWZLdjZrMUJmTlBTUUozTHA5YldtWG90YlZ1Q3dHOE
1ZYyJ9fQ.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleG
FtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSA
xMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxp
dHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUsImNvd
W50cnkiOiJVU0EifQ~dHJ1ZQ.J2d9Pwt4aeSJe1HPsw7ZV2q9IoPsjIPL_Z0iwn0vaLnK
9t4UEBm2MQhmDLQqfOsgHRBih2kXs14vl35KifBwkg~viTkELowl0XTNCE1-7XGfrHwoT
SqUngT6vaSIifAxJc

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

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

For presentation with the following presentation protected header:¶

{
  "alg": "MAC-H256",
  "aud": "https://recipient.example.com",
  "nonce": "IzLqrQVM9yrSBup5bfo6kqmpkEJje_7-9xaEA6XQwe0"
}

Figure 24: Presentation Protected Header

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

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

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

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

[
  "J2d9Pwt4aeSJe1HPsw7ZV2q9IoPsjIPL_Z0iwn0vaLnK9t4UEBm2MQhmDLQqfOsgHR
Bih2kXs14vl35KifBwkg",
  "es3kijhQC4j8J3VFPB5iq155k6FY_1qWAwQk8bWVuR0",
  "r4pLHitd8P21XoD386rDO2TI_pC4hHOf5wtgYjF_0mw",
  "vqhs2s7HLNXszH0G4nHv2r3POiATPe-iLbNzsruLiL4",
  "3EmR33Z1-5422A3bX4vhsdVOSMUadh2s5369is59-PQ",
  "7xeJUlpW1tgXs13Nrkm3-IDJHgDfXzTv07j9i92Tl38",
  "YYnQz9reV1m0oI6kP5yjwSt3IreVluEJ1hXleq4kYpY",
  "qSzTOXw7EL3EbCA-t8JQSE670Z0ku1zjMrdicHajr0A",
  "rOnqp69ruW7FN4Nw-icmTxiXlOWpuccrK25yWazSXhQFppnBVFSl6ST415aj2i71pr
nisIwi5xYYZcWPk8Pg2Q"
]

Figure 25: Presentation proof (Base64url-Encoded)

The final presented JWP in compact serialization is:¶

eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJJekxxclFWTTl5clNCdXA1YmZvNmtxbXBrRUpqZV83LTl4YUVBNl
hRd2UwIn0.eyJhbGciOiJNQUMtSDI1NiIsImhwYSI6IkVTMjU2IiwidHlwIjoiSlBUIiw
iaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsImNsYWltcyI6WyJpYXQiLCJleHAi
LCJmYW1pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb
3Zlcl8yMSJdLCJwcmVzZW50YXRpb25fa2V5Ijp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNT
YiLCJ1c2UiOiJzaWduIiwieCI6IkVrWC1DeGNfcmlKZk1JdjdqXzA3ck5HNnVSWDZGQ25
wZXpuNGlaQnU5RHciLCJ5IjoiZUdNWWlOckt1OWZLdjZrMUJmTlBTUUozTHA5YldtWG90
YlZ1Q3dHOE1ZYyJ9fQ.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.J
2d9Pwt4aeSJe1HPsw7ZV2q9IoPsjIPL_Z0iwn0vaLnK9t4UEBm2MQhmDLQqfOsgHRBih2
kXs14vl35KifBwkg~es3kijhQC4j8J3VFPB5iq155k6FY_1qWAwQk8bWVuR0~r4pLHitd
8P21XoD386rDO2TI_pC4hHOf5wtgYjF_0mw~vqhs2s7HLNXszH0G4nHv2r3POiATPe-iL
bNzsruLiL4~3EmR33Z1-5422A3bX4vhsdVOSMUadh2s5369is59-PQ~7xeJUlpW1tgXs1
3Nrkm3-IDJHgDfXzTv07j9i92Tl38~YYnQz9reV1m0oI6kP5yjwSt3IreVluEJ1hXleq4
kYpY~qSzTOXw7EL3EbCA-t8JQSE670Z0ku1zjMrdicHajr0A~rOnqp69ruW7FN4Nw-icm
TxiXlOWpuccrK25yWazSXhQFppnBVFSl6ST415aj2i71prnisIwi5xYYZcWPk8Pg2Q

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

Appendix C. Document History

[[ To be removed from the final specification ]] -10¶

Clarify MAC issuance and presentation using new "payload slot" nomenclature.¶
Define a new binary "Presentation Internal Representation" so that the holder signature protects the entire presentation¶
Leverage the new "Holder Presentation Algorithm" to allow the holder algorithm to be independant from the signature algorithm used by the issuer¶
Redefine computation of the "Combined MAC Representation" to more closely match the new Presentation Internal Representation.¶
Change the MAC algorithm to directly sign the binary Combined MAC Representation rather than convert it to a JWS.¶
Do not unneccessarily hash the issuer protected header inside the Combined MAC Representation, so that it can provide some manner of domain separation.¶
Clarify how verifiers are to generate the Combined MAC Representation from available information.¶
Provider step-by-step instructions for verification of a presentation¶

-09¶

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

-08¶

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

-07¶

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

-06¶

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

-05¶

Update of appendix describing MAC-H256 to now also be generated by the build system from a common set of code and templates.¶
Update single use algorithm to use an array of octet values rather than requiring splitting an octet buffer into parts during generation of a presentation and during verification.¶
Update BBS algorithm description and examples to clarify the proof is an array with a single octet string.¶
Update MAC algorithm to use an array of octet values for the proof, rather than requiring splitting an octet buffer into parts.¶
Add new section on the Combined MAC Representation to clarify operations are serving to recreate this octet string value.¶
Correct reference to the latest BBS draft.¶
SU and MAC families now use raw JWA rather than JWS and synthesized headers¶
Change algorithms to not use base64url-encoding internally. Algorithms are meant to operate on octets, while base64url-encoding is used to represent those octets in JSON and compact serializations.¶

-04¶

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

-03¶

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

-02¶

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

-01¶

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

-00¶

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