| Internet-Draft | json-proof-algorithms | July 2024 |
| Miller, et al. | Expires 9 January 2025 | [Page] |
The JSON Proof Algorithms (JPA) specification registers cryptographic algorithms and identifiers to be used with the JSON Web Proof and JSON Web Key (JWK) specifications. It defines IANA registries for these identifiers.¶
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
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This Internet-Draft will expire on 9 January 2025.¶
Copyright (c) 2024 IETF Trust and the persons identified as the document authors. All rights reserved.¶
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The JSON Web Proof (JWP) [I-D.ietf-jose-json-web-proof] draft establishes a new secure container format that supports selective disclosure and unlinkability using Zero-Knowledge Proofs (ZKPs) or other cryptographic algorithms.¶
Editor's Note: This draft is still early and incomplete. There will be significant changes to the algorithms as currently defined here. Please do not use any of these definitions or examples for anything except personal experimentation and learning. Contributions and feedback are welcomed at https://github.com/json-web-proofs/json-web-proofs.¶
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.¶
The roles of "issuer", "holder", and "verifier" are used as defined by the VC Data Model [VC-DATA-MODEL-2.0]. The term "presentation" is also used as defined by this source, but the term "credential" is avoided in this specification to minimize confusion with other definitions.¶
The terms "JSON Web Signature (JWS)", "Base64url Encoding", "Header Parameter", "JOSE Header", "JWS Payload", "JWS Signature", and "JWS Protected Header" are defined by [RFC7515].¶
The terms "JSON Web Proof (JWP)", "JWP Payload", "JWP Proof", and "JWP Protected Header" are defined by [I-D.ietf-jose-json-web-proof].¶
These terms are defined by this specification:¶
JWP defines a container binding together a protected header, one or more payloads, and a cryptographic proof. It does not define any details about the interactions between an application and the cryptographic libraries that implement proof-supporting algorithms.¶
Due to the nature of ZKPs, this specification also documents the subtle but important differences in proof algorithms versus those defined by the JSON Web Algorithms [RFC7518]. These differences help support more advanced capabilities such as blinded signatures and predicate proofs.¶
The four principal interactions that every proof algorithm MUST support are [issue](#issue), [confirm](#confirm), [present](#present), and [verify](#verify).¶
The JWP is first created as the output of a JPA's issue operation.¶
Every algorithm MUST support a JSON issuer protected header along with one or more octet string payloads. The algorithm MAY support using additional items provided by the holder for issuance such as blinded payloads, keys for replay prevention, etc.¶
All algorithms MUST provide integrity protection for the issuer header and all payloads and MUST specify all digest and/or hash2curve methods used.¶
Performed by the holder to validate that the issued JWP is correctly formed and protected.¶
Each algorithm MAY support using additional input items options, such as those sent to the issuer for issuance. After confirmation, an algorithm MAY return a modified JWP for serialized storage without the local state (such as with blinded payloads now unblinded).¶
The algorithm MUST fully verify the issued proof value against the issuer protected header and all payloads. If given a presented JWP instead of an issued one, the confirm process MUST return an error.¶
Used to apply any selective disclosure choices and perform any unlinkability transformations, as well as to show binding.¶
An algorithm MAY support additional input options from the requesting party, such as for predicate proofs and verifiable computation requests.¶
Every algorithm MUST support the ability to hide any or all payloads. It MUST always include the issuer protected header unmodified in the presentation.¶
The algorithm MUST replace the issued proof value and generate a new presented proof value. It also MUST include a new presentation protected header that provides replay protection.¶
Performed by the verifier to verify the protected headers along with any disclosed payloads and/or assertions about them from the proving party, while also verifying they are the same payloads and ordering as witnessed by the issuer.¶
The algorithm MUST verify the integrity of all disclosed payloads and MUST also verify the integrity of both the issuer and presentation protected headers.¶
If the presented proof contains any assertions about the hidden payloads, the algorithm MUST also verify all of those assertions. It MAY support additional options, such as those sent to the holder to generate the presentation.¶
If given an issued JWP for verification, the algorithm MUST return an error.¶
This section defines how to use specific algorithms for JWPs.¶
Editor's Note: This algorithm may be renamed and slightly refactored.¶
The Single Use (SU) algorithm is based on composing multiple traditional JWS values into a single JWP proof value. 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).¶
The Single Use algorithm is based on using multiple JWS values, all of which are generated with the same JSON Web Algorithm (JWA) for signing. This JWA identifier is included as part of the Single Use identifier for JWP.¶
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.¶
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 easily accomplished by the holder using this key to generate a JWS that signs a value the issuer can verify as unique.¶
To create a Single Use JWP, the issuer first generates a unique Ephemeral Key using the selected JWS algorithm. This key-pair will be used to sign each of the payloads of a single JWP and then discarded.¶
JSON Web Signatures are used to create all of the signature values used by the SU algorithm. This allows an implementation to use an existing JWS library directly for all necessary cryptographic operations without requiring any additional primitives.¶
Each individual JWS uses a fixed protected header containing only the minimum required alg value. Since this JWS protected header itself is the same for every JWS, it SHOULD be a static value in the form of {"alg":"***"} where *** is the JWA asymmetric signing key algorithm identifier being used. This value is recreated by a verifier using the correct JWA algorithm value included in the SU algorithm identifier.¶
If an implementation uses an alternative JWS protected header than this fixed value, a base64url encoded serialized form of the alternate fixed header MUST be included using the jws_header claim in the issuer protected header.¶
The JWK of the issuer's Ephemeral Key MUST be included in the issuer protected header with the property name of proof_jwk and contain only the REQUIRED values to represent the public key.¶
The holder's Presentation Key JWK MUST be included in issuer protected header using the presentation_jwk claim.¶
The final issuer protected header is then used directly as the body of a JWS and signed using the issuer's Stable Key. The resulting JWS signature value unencoded octet string is the first value in the JWP proof.¶
In various examples in this specification, the octet string serialized issuer header is referenced as issuer_header.¶
Each JWP payload is processed in order and signed as a JWS body using the issuer's Ephemeral Key. The resulting JWS signature value unencoded octet string is appended to the JWP proof.¶
The proof value as an octet string will have a total length that is the sum of the fixed length of the issuer protected header signature plus the fixed length of each of the payload Ephemeral Key signatures. For example, the signature for the ES256 algorithm is 64 octets and for a JWP with five payloads the total proof value length would be 64 * (1 + 5) = 384 octets).¶
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 claim 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 claims SHOULD NOT contain values that are common across multiple presentations and SHOULD be unique to a single presentation and verifier.¶
In various examples in this specification, the octet string serialized presentation header is referenced as presentation_header.¶
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 value when presenting it to a verifier. 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 value is always the holder's Presentation Key signature of the presentation protected header, constructed identically to the issuer protected header by using the serialized JSON value octet string as the JWS body. 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.¶
The two header signatures are then followed by only the issuer's Ephemeral Key signatures for each payload that is disclosed. The order of the payload signatures is preserved and MUST be in the same order as the included disclosed payloads in the presented JWP. Non-disclosed payloads will NOT have a signature value included. For example, if the second and fifth payloads are hidden then the holder's derived proof value would be of the length 64 * (1 + 1 + the 1st, 2nd, and 4th payload signatures) = 320 octets.¶
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.¶
The verifier MUST verify the issuer protected header against the first matching JWS signature part in the proof value using the issuer's Stable Key. It MUST also verify the presentation protected header against the second JWS signature part in the proof value using the holder's Presentation Key as provided in the presentation_jwk claim in the issuer protected header.¶
With the headers verified, the issuer's Ephemeral Key as given in the issuer protected header proof_jwk claim can then be used to verify each of the disclosed payload signatures.¶
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".¶
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.¶
The BBS alg parameter value in the issuance protected header corresponds to a ciphersuite identifier of BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_.¶
The BBS-PROOF alg parameter value in the presentation protected header corresponds to the same ciphersuite, but used in presentation form.¶
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 form of this key is an OKP type with a curve of BLS12381G2, with x being the BASE64URL-encoded form of the output of point_to_octets_E2. The use of this curve is described in [I-D.ietf-cose-bls-key-representations].¶
There is no additional holder key necessary for presentation proofs.¶
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 the issuance proof, to be used along with the protected header and payloads to serialize the JWP.¶
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.¶
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.¶
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.¶
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.¶
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 JWS-based JPA, 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.¶
Prior to the issuer creating a new JWP, it must have presentation binding information provided by the holder. This enables the holder to perform replay prevention while presenting the JWP.¶
The presentation key used by the holder must be transferred to the issuer and verified, likely through a challenge and self-signing mechanism. If the holder requires unlinkability, it must also generate a new key that is verified and bound to each new JWP.¶
How these holder presentation keys are transferred and verified is out of scope of this specification. Protocols such as OpenID Connect can be used to accomplish this. What is required by this definition is that the holder's presentation key MUST be included in the issuer's protected header using the pjwk claim with a JWK as the value.¶
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.¶
The holder's presentation key JWK MUST be included in the issuer protected header using the pjwk claim. The issuer MUST validate that the holder has possession of this key through a trusted mechanism such as verifying the signature of a unique nonce value from the holder.¶
For consistency, the issuer header is also protected by a MAC by using the fixed value "issuer_header" as the input key. The issuer header JSON is serialized using UTF-8 and encoded with base64url into an octet array. The final issuer header MAC is generated from the octet array and the fixed key, and the resulting value becomes the first input into the larger octet array that will be signed by the issuer.¶
A unique key is generated for each payload using the MAC with the Shared Secret as the key and the values "payload_X" where "X" is replaced by the zero-based array index of the payload, for example "payload_0", "payload_1", etc.¶
Each payload is serialized using UTF-8 and encoded with base64url into an octet array. The generated key for that payload based on its index is used to generate the MAC for the payload's encoded octet array. The resulting value is appended to the larger octet array that will be signed by the issuer.¶
The issuer proof consists of two items appended together: the issuer's signature of the appended array of MACs and the Shared Secret used to generate the set of payload keys.¶
To generate the signature, the array containing the final MAC of the issuer protected header followed by all of the payload MACs appended in order is used as the input to a new JWS.¶
jws_payload = [issuer_header_mac, payload_mac_1, ... payload_mac_n]¶
The issuer signs the JWS using its stable public key and a fixed header containing the alg associated with MAC algorithm in use.¶
jws_header = '{"alg":"ES256"}'¶
The resulting signature is decoded and used as the first item in the issuer proof value. The octet array of the Shared Secret is appended, resulting in the final issuer proof value.¶
issuer_proof = [jws_signature, shared_secret]¶
See the JWS Presentation Protected Header section.¶
Editor's Note: The current definition here is incomplete, the holder's signature needs to also incorporate the presented proof.¶
The presentation proof is constructed as a large octet array containing multiple appended items similar to the issuer proof value. The first item is the JWS decoded signature value generated when the holder uses the presentation key to sign the presentation header. The second item is the issuer signature from the issuer's proof value.¶
These two signatures are then followed by a MAC value for each payload. The MAC values used will depend on whether that payload has been disclosed or is hidden. Disclosed payloads will include the MAC key input, and hidden payloads will include only their final MAC value.¶
presentation_proof = [presentation_signature, issuer_signature,
disclosed_key_0, hidden_mac_1, hidden_mac_2,
... disclosed_key_n]
¶
The size of this value will depend on the underlying cryptographic algorithms. For example, MAC-H256 uses the ES256 JWS with a decoded signature of 64 octets, and for a JWP with five payloads using HMAC-SHA256 the total presentation proof value length would be 64 + 64 + (5 * 32) = 288 octets.¶
To verify that the presentation was protected from replay attacks, the verifier must be able to validate the presentation protected header. This involves the following steps:¶
nonce claim¶
pjwk claim¶
alg value and the presentation header as the body¶
presentation_signature from the beginning of the presentation_proof octet array¶
pjwk claim and the presentation_signature value¶
Next, the verifier must validate all of the disclosed payloads using the following steps:¶
kid using a trusted mechanism to obtain the correct issuer JWK¶
issuer_signature from the beginning of the remaining presentation_proof octet array (after the presentation_signature was removed)¶
issuer_header value using the "issuer_header" value as the input key¶
jws_payload octet array¶
Iterate on each presented payload (disclosed or hidden)¶
presentation_proof octet array¶
jws_payload octet array¶
jws_payload octet array¶
alg parameter along with the generated jws_payload value as the payload¶
issuer_signature value¶
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¶
Editor's Note: This will follow once the algorithms defined here have become more stable.¶
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.¶
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.¶
Issued or Presented. Other values may be used with the approval of a Designated Expert.¶
SU-ES256¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: SU-ES384¶
Algorithm Description: Single-Use JWP using ES384¶
Algorithm Usage Location(s): Issued, Presented¶
JWP Implementation Requirements: Optional¶
Change Controller: IETF¶
Specification Document(s): Section 6.1.10 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: SU-ES512¶
Algorithm Description: Single-Use JWP using ES512¶
Algorithm Usage Location(s): Issued, Presented¶
JWP Implementation Requirements: Optional¶
Change Controller: IETF¶
Specification Document(s): Section 6.1.10 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: BBS¶
Algorithm Description: Corresponds to a ciphersuite identifier of BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_H2G_HM2S_¶
Algorithm Usage Location(s): Issued¶
JWP Implementation Requirements: Required¶
Change Controller: IETF¶
Specification Document(s): Section 6.2.1 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: BBS-PROOF¶
Algorithm Description: Corresponds to a ciphersuite identifier of BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_H2G_HM2S_¶
Algorithm Usage Location(s): Presented¶
JWP Implementation Requirements: Required¶
Change Controller: IETF¶
Specification Document(s): Section 6.2.1 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: MAC-H256¶
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 6.3.9 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: MAC-H384¶
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 6.3.9 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: MAC-H512¶
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 6.3.9 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: MAC-K25519¶
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 6.3.9 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: MAC-K448¶
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 6.3.9 of this specification¶
Algorithm Analysis Documents(s): n/a¶
Algorithm Name: MAC-H256K¶
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 6.3.9 of this specification¶
Algorithm Analysis Documents(s): n/a¶
This section registers the following Header Parameter names defined by this specification in the IANA "JSON Web Proof Header Parameters" registry established by [I-D.ietf-jose-json-web-proof].¶
proof_jwk¶
Specification Document(s): Section 6.1.5 of this specification¶
Header Parameter Name: presentation_jwk¶
Header Parameter Description: Holder's Presentation Key¶
Header Parameter Usage Location(s): Issued¶
Change Controller: IETF¶
Specification Document(s): Section 6.1.5 of this specification¶
The following examples use algorithms defined in JSON Proof Algorithms and also contain the keys used, so that implementations can validate these samples.¶
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": "VkXZyg2WWjdUKVBA4yOzz90txc5kx7sWqLT9S8FQuLk",
"y": "hRaew6pjLBwetqErF3ohct8TNqAk9jrTtPbHvb47ZnI",
"d": "dLCfKVGT7RMcnV-kBi2OacF28dDBoHQ1uJlW_l2C-GQ"
}
This is the ephemeral private key used in this example in the JWK format:¶
{
"kty": "EC",
"crv": "P-256",
"x": "rMo0sZWv2-Qx7CcjLg-PagmPmR_XLNj5WWSg8QhC34w",
"y": "367xmsgSBX3RT_rplwwVNrLVGEtaBqNhUzFGbM2jaF8",
"d": "h9jv7uKIxpE84VaPRjiOhPpOwzlrLHByn6sI5oZCdS0"
}
This is the Holder's presentation private key used in this example in the JWK format:¶
{
"kty": "EC",
"crv": "P-256",
"x": "UcihXPGqIEA9e_SXVRGNpV7mOaQwU9rLKVgPpbSz8ko",
"y": "gHXjB6UeP8Qqt4pdmqPxySJKRd_AaBjo_9onbsE76yk",
"d": "Rxl8R-FImuqjMJrnpPrFmUYIxDjRNM7NtwEhym_iGf0"
}
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_jwk": {
"kty": "EC",
"crv": "P-256",
"x": "rMo0sZWv2-Qx7CcjLg-PagmPmR_XLNj5WWSg8QhC34w",
"y": "367xmsgSBX3RT_rplwwVNrLVGEtaBqNhUzFGbM2jaF8",
"d": "h9jv7uKIxpE84VaPRjiOhPpOwzlrLHByn6sI5oZCdS0"
},
"presentation_jwk": {
"kty": "EC",
"crv": "P-256",
"x": "UcihXPGqIEA9e_SXVRGNpV7mOaQwU9rLKVgPpbSz8ko",
"y": "gHXjB6UeP8Qqt4pdmqPxySJKRd_AaBjo_9onbsE76yk",
"d": "Rxl8R-FImuqjMJrnpPrFmUYIxDjRNM7NtwEhym_iGf0"
}
}
The JWP Protected Header is serialized (without the above whitespace added for readability) into UTF-8, then BASE64URL-encoded. This gives:¶
eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL mV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUiLCJnaXZlbl 9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJvb2ZfandrIjp 7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ4Ijoick1vMHNaV3YyLVF4N0NjakxnLVBh Z21QbVJfWExOajVXV1NnOFFoQzM0dyIsInkiOiIzNjd4bXNnU0JYM1JUX3JwbHd3Vk5yT FZHRXRhQnFOaFV6RkdiTTJqYUY4IiwiZCI6Img5anY3dUtJeHBFODRWYVBSamlPaFBwT3 d6bHJMSEJ5bjZzSTVvWkNkUzAifSwicHJlc2VudGF0aW9uX2p3ayI6eyJrdHkiOiJFQyI sImNydiI6IlAtMjU2IiwieCI6IlVjaWhYUEdxSUVBOWVfU1hWUkdOcFY3bU9hUXdVOXJM S1ZnUHBiU3o4a28iLCJ5IjoiZ0hYakI2VWVQOFFxdDRwZG1xUHh5U0pLUmRfQWFCam9fO W9uYnNFNzZ5ayIsImQiOiJSeGw4Ui1GSW11cWpNSnJucFByRm1VWUl4RGpSTk03TnR3RW h5bV9pR2YwIn19
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"}. The JWS payload for each varies and the resulting signature value is used in its unencoded form (the octet string, not the base64url-encoded form).¶
The final Proof value from the Issuer is the concatenated array of the header signature followed by all of the payload signatures, then base64url encoded.¶
The resulting JSON serialized JPT using the above examples is:¶
{
"issuer": "eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz
Oi8vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaW
x5X25hbWUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292
ZXJfMjEiXSwicHJvb2ZfandrIjp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLC
J4Ijoick1vMHNaV3YyLVF4N0NjakxnLVBhZ21QbVJfWExOajVXV1NnOFFoQzM0
dyIsInkiOiIzNjd4bXNnU0JYM1JUX3JwbHd3Vk5yTFZHRXRhQnFOaFV6RkdiTT
JqYUY4IiwiZCI6Img5anY3dUtJeHBFODRWYVBSamlPaFBwT3d6bHJMSEJ5bjZz
STVvWkNkUzAifSwicHJlc2VudGF0aW9uX2p3ayI6eyJrdHkiOiJFQyIsImNydi
I6IlAtMjU2IiwieCI6IlVjaWhYUEdxSUVBOWVfU1hWUkdOcFY3bU9hUXdVOXJM
S1ZnUHBiU3o4a28iLCJ5IjoiZ0hYakI2VWVQOFFxdDRwZG1xUHh5U0pLUmRfQW
FCam9fOW9uYnNFNzZ5ayIsImQiOiJSeGw4Ui1GSW11cWpNSnJucFByRm1VWUl4
RGpSTk03TnR3RWh5bV9pR2YwIn19",
"payloads": [
"MTcxNDUyMTYwMA",
"MTcxNzE5OTk5OQ",
"IkRvZSI",
"IkpheSI",
"ImpheWRvZUBleGFtcGxlLm9yZyI",
"eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
ImNvdW50cnkiOiJVU0EifQ",
"dHJ1ZQ"
],
"proof": "ocCREex2_WCO24zJKPKrTXVDwJ2bZELf4b1ltrEdg80joqXWQKsUXLaO0
-JtUdZaXdHSOyMZawLIX9zLOz587AmQIdkBwvfBxghU8_YLQlptnf4iGVQnanz
1Kf73HMI7ooGTkq1JXKm3KoZQGu7oTDPbg4_jjBrf2JJKLJg1K88j_1j6Mv8yN
0Hmdc0royndgHmFH4KNxDhrzwyS_KihV9bUgH0ytesfW5CVXXux9r5mnNlTLK9
FJiVPpP66sMrxewXpxQz7wMUFXLAcJBgM40Rjoc2x-lPA2IiYKWkGcCAKpVS92
71JNAJyaKGMxKH3awrnzAM3Z1g7UpGe3PgvvjtQkMRypQSVwv7rP0GoVB8sm_g
pswQ8FSmcrAxw16xYKFzcju23hxwkC2m_fY9uHBRdU-gfhyrRjAZR6k9yH6Ujo
0ST4P78AQgxEj4U7jMGwnR5gJ_iVh22nGTGRzA6w-Eg8niiQ0PKcPajpvHRhwk
yqiuEeEsgWWpKnDDD-hc14RTraEeIJCLgxFRPx_o7pCGW8J-L758IG3P2UwVzW
TmYzCwX7NLaEcenZXMOzPMd7SFtlzgIZZ1IHWd8-p6exV_kddPRqqDH4tQevQN
q_Ai9glKAU963uTp3PKRkYlhEENLKxfLzOFHVahYiCBReGME-NCV55mdOwk8pW
JLvr1Y"
}
The compact serialization of the same JPT is:¶
eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8vaXNzdWVyL mV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUiLCJnaXZlbl 9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJvb2ZfandrIjp 7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ4Ijoick1vMHNaV3YyLVF4N0NjakxnLVBh Z21QbVJfWExOajVXV1NnOFFoQzM0dyIsInkiOiIzNjd4bXNnU0JYM1JUX3JwbHd3Vk5yT FZHRXRhQnFOaFV6RkdiTTJqYUY4IiwiZCI6Img5anY3dUtJeHBFODRWYVBSamlPaFBwT3 d6bHJMSEJ5bjZzSTVvWkNkUzAifSwicHJlc2VudGF0aW9uX2p3ayI6eyJrdHkiOiJFQyI sImNydiI6IlAtMjU2IiwieCI6IlVjaWhYUEdxSUVBOWVfU1hWUkdOcFY3bU9hUXdVOXJM S1ZnUHBiU3o4a28iLCJ5IjoiZ0hYakI2VWVQOFFxdDRwZG1xUHh5U0pLUmRfQWFCam9fO W9uYnNFNzZ5ayIsImQiOiJSeGw4Ui1GSW11cWpNSnJucFByRm1VWUl4RGpSTk03TnR3RW h5bV9pR2YwIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRv ZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duL CBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG 9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDU sImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.ocCREex2_WCO24zJKPKrTXVDwJ2bZELf4b1ltr Edg80joqXWQKsUXLaO0-JtUdZaXdHSOyMZawLIX9zLOz587AmQIdkBwvfBxghU8_YLQlp tnf4iGVQnanz1Kf73HMI7ooGTkq1JXKm3KoZQGu7oTDPbg4_jjBrf2JJKLJg1K88j_1j6 Mv8yN0Hmdc0royndgHmFH4KNxDhrzwyS_KihV9bUgH0ytesfW5CVXXux9r5mnNlTLK9FJ iVPpP66sMrxewXpxQz7wMUFXLAcJBgM40Rjoc2x-lPA2IiYKWkGcCAKpVS9271JNAJyaK GMxKH3awrnzAM3Z1g7UpGe3PgvvjtQkMRypQSVwv7rP0GoVB8sm_gpswQ8FSmcrAxw16x YKFzcju23hxwkC2m_fY9uHBRdU-gfhyrRjAZR6k9yH6Ujo0ST4P78AQgxEj4U7jMGwnR5 gJ_iVh22nGTGRzA6w-Eg8niiQ0PKcPajpvHRhwkyqiuEeEsgWWpKnDDD-hc14RTraEeIJ CLgxFRPx_o7pCGW8J-L758IG3P2UwVzWTmYzCwX7NLaEcenZXMOzPMd7SFtlzgIZZ1IHW d8-p6exV_kddPRqqDH4tQevQNq_Ai9glKAU963uTp3PKRkYlhEENLKxfLzOFHVahYiCBR eGME-NCV55mdOwk8pWJLvr1Y
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": "wcCjytIDLGL8tLfbTqo_d8DRZSj-FAYLwTyiXwM5ljE"
}
When serialized without formatting and BASE64URL-encoded, this results in the string:¶
eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY 29tIiwibm9uY2UiOiJ3Y0NqeXRJRExHTDh0TGZiVHFvX2Q4RFJaU2otRkFZTHdUeWlYd0 01bGpFIn0
When signed with the holder's presentation key, the resulting signature are:¶
bm9RdTFQczRJMDBzdTJ5VFNidEhhNkJTMURkSGxUV2lLR25WeFdpLW15eUlfRkpKeUhES XhfeFFoUnZIU0tqeG9mMzRnRU50Q0ZPOHR3YVRoMGMydHc¶
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
BpZW50LmV4YW1wbGUuY29tIiwibm9uY2UiOiJ3Y0NqeXRJRExHTDh0TGZiVHFv
X2Q4RFJaU2otRkFZTHdUeWlYd001bGpFIn0",
"issuer": "eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBz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",
"payloads": [
"MTcxNDUyMTYwMA",
"MTcxNzE5OTk5OQ",
"IkRvZSI",
"IkpheSI",
"ImpheWRvZUBleGFtcGxlLm9yZyI",
"eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b3duLCBDQSAxMjM0NVxu
VVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIiwibG9jYWxpdH
kiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTIzNDUs
ImNvdW50cnkiOiJVU0EifQ",
"dHJ1ZQ",
null,
null
],
"proof": "b2NDUkVleDJfV0NPMjR6SktQS3JUWFZEd0oyYlpFTGY0YjFsdHJFZGc4M
GpvcVhXUUtzVVhMYU8wLUp0VWRaYVhkSFNPeU1aYXdMSVg5ekxPejU4N0o2RUx
0VDdPQ05OTEx0c2swbTdSMnVnVXRRM1I1VTFvaWhwMWNWb3Zwc3NpUHhTU2Nod
3lNZjhVSVVieDBpbzhhSDktSUJEYlFoVHZMY0drNGRITnJjSmtDSFpBY0wzd2N
ZSVZQUDJDMEphYlozLUlobFVKMnA4OVNuLTl4ekNPNktCazVLdFNWeXB0eXFHV
UJydTZFd3oyNE9QNDR3YTM5aVNTaXlZTlN2UElfOVktakxfTWpkQjVuWE5LNk1
wM1lCNWhSLUNqY1E0YTg4TWt2eW9vVmZXMUlCOU1yWHJIMXVRbFYxN3NmYS1ac
HpaVXl5dlJTWWxUNlQtdXJESzhYc0Y2Y1VNLThERkJWeXdIQ1FZRE9ORVk2SE5
zZnBUd05pSW1DbHBCbkFnQ3FWVXZkdTlTVFFDY21paGpNU2g5MnNLNTh3RE4yZ
FlPMUtSbnR6NEw3NDdVSkRFY3FVRWxjTC02ejlCcUZRZkxKdjRLYk1FUEJVcG5
Ld01jTmVzV0NoYzNJN3R0NGNjSkF0cHYzMlBiaHdVWFZQb0g0Y3EwWXdHVWVwU
GNoLWxJNk5Fay1ELV9BRUlNUkktRk80ekJzSjBlWUNmNGxZZHRweGt4a2N3T3N
QaElQSjRva05EeW5EMm82YngwWWNKTXFvcmhIaExJRmxxU3B3d3dfb1hOUQ"
}
¶
Figure: Final Presentation in JSON Serialization¶
And also in compact serialization:¶
eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY 29tIiwibm9uY2UiOiJ3Y0NqeXRJRExHTDh0TGZiVHFvX2Q4RFJaU2otRkFZTHdUeWlYd0 01bGpFIn0.eyJhbGciOiJTVS1FUzI1NiIsInR5cCI6IkpQVCIsImlzcyI6Imh0dHBzOi8 vaXNzdWVyLmV4YW1wbGUiLCJjbGFpbXMiOlsiaWF0IiwiZXhwIiwiZmFtaWx5X25hbWUi LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZGRyZXNzIiwiYWdlX292ZXJfMjEiXSwicHJvb 2ZfandrIjp7Imt0eSI6IkVDIiwiY3J2IjoiUC0yNTYiLCJ4Ijoick1vMHNaV3YyLVF4N0 NjakxnLVBhZ21QbVJfWExOajVXV1NnOFFoQzM0dyIsInkiOiIzNjd4bXNnU0JYM1JUX3J wbHd3Vk5yTFZHRXRhQnFOaFV6RkdiTTJqYUY4IiwiZCI6Img5anY3dUtJeHBFODRWYVBS amlPaFBwT3d6bHJMSEJ5bjZzSTVvWkNkUzAifSwicHJlc2VudGF0aW9uX2p3ayI6eyJrd HkiOiJFQyIsImNydiI6IlAtMjU2IiwieCI6IlVjaWhYUEdxSUVBOWVfU1hWUkdOcFY3bU 9hUXdVOXJMS1ZnUHBiU3o4a28iLCJ5IjoiZ0hYakI2VWVQOFFxdDRwZG1xUHh5U0pLUmR fQWFCam9fOW9uYnNFNzZ5ayIsImQiOiJSeGw4Ui1GSW11cWpNSnJucFByRm1VWUl4RGpS Tk03TnR3RWh5bV9pR2YwIn19.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheS I~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5 Bbnl0b3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4g U3QuIiwibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZ SI6MTIzNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ~~.b2NDUkVleDJfV0NPMjR6SktQS3 JUWFZEd0oyYlpFTGY0YjFsdHJFZGc4MGpvcVhXUUtzVVhMYU8wLUp0VWRaYVhkSFNPeU1 aYXdMSVg5ekxPejU4N0o2RUx0VDdPQ05OTEx0c2swbTdSMnVnVXRRM1I1VTFvaWhwMWNW b3Zwc3NpUHhTU2Nod3lNZjhVSVVieDBpbzhhSDktSUJEYlFoVHZMY0drNGRITnJjSmtDS FpBY0wzd2NZSVZQUDJDMEphYlozLUlobFVKMnA4OVNuLTl4ekNPNktCazVLdFNWeXB0eX FHVUJydTZFd3oyNE9QNDR3YTM5aVNTaXlZTlN2UElfOVktakxfTWpkQjVuWE5LNk1wM1l CNWhSLUNqY1E0YTg4TWt2eW9vVmZXMUlCOU1yWHJIMXVRbFYxN3NmYS1acHpaVXl5dlJT WWxUNlQtdXJESzhYc0Y2Y1VNLThERkJWeXdIQ1FZRE9ORVk2SE5zZnBUd05pSW1DbHBCb kFnQ3FWVXZkdTlTVFFDY21paGpNU2g5MnNLNTh3RE4yZFlPMUtSbnR6NEw3NDdVSkRFY3 FVRWxjTC02ejlCcUZRZkxKdjRLYk1FUEJVcG5Ld01jTmVzV0NoYzNJN3R0NGNjSkF0cHY zMlBiaHdVWFZQb0g0Y3EwWXdHVWVwUGNoLWxJNk5Fay1ELV9BRUlNUkktRk80ekJzSjBl WUNmNGxZZHRweGt4a2N3T3NQaElQSjRva05EeW5EMm82YngwWWNKTXFvcmhIaExJRmxxU 3B3d3dfb1hOUQ¶
Figure: Final Presentation in Compact Serialization¶
The following example uses the BBS algorithm.¶
This is the Signer's stable private key in the JWK format:¶
{
"kty": "EC2",
"alg": "BBS",
"use": "proof",
"crv": "BLS12381G2",
"x": "EXjk9Z3gSYpTQPNkwbbrlbkyyewAqF1dSq3JAB8ure9qIHn2ntHd8A0JZwkzt
K6_GW3y_CBGsenon94QcWbeBhk2L25GGDCfe9OnHTGhKT63c5ly2g3p9DLYbAs
PigAX",
"y": "Dm9cwrYygzEaim535XHZ3WSfjkJUPzluwEWsltiEbKPq43rApsLjNXotBGywr
kHAFVn-YjYT31Bw2Ey39pdtK6rtz9wcTeh0Xlwu1cM0vr95CxyTdo1hJpRapLR
WSI7v",
"d": "GrxJZxt8ejFPn2HcN3bMZjlx3UNh6trylgKCInEXLQw"
}
There is no additional holder key necessary for presentation proofs.¶
For the following protected header and array of payloads:¶
{
"kid": "HjfcpyjuZQ-O8Ye2hQnNbT9RbbnrobptdnExR0DUjU8",
"alg": "BBS"
}
[
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
]
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": "gc1DypkHNTDp9d4brKngswYHhnYepJrW2txnZXDRPdgtjph-X1CmiepoW
C_H5_IhValvNE7DjkJt15ovoLrXJzbqAV5MfMIa_5t6J3Mn1Dk"
}
eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRuRXhSMERValU4I iwiYWxnIjoiQkJTIn0.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~Imph eWRvZUBleGFtcGxlLm9yZyI~eyJmb3JtYXR0ZWQiOiIxMjM0IE1haW4gU3QuXG5Bbnl0b 3duLCBDQSAxMjM0NVxuVVNBIiwic3RyZWV0X2FkZHJlc3MiOiIxMjM0IE1haW4gU3QuIi wibG9jYWxpdHkiOiJBbnl0b3duIiwicmVnaW9uIjoiQ0EiLCJwb3N0YWxfY29kZSI6MTI zNDUsImNvdW50cnkiOiJVU0EifQ~dHJ1ZQ.gc1DypkHNTDp9d4brKngswYHhnYepJrW2t xnZXDRPdgtjph-X1CmiepoWC_H5_IhValvNE7DjkJt15ovoLrXJzbqAV5MfMIa_5t6J3M n1Dk
For a presentation with the following presentation header:¶
{
"alg": "BBS-PROOF",
"aud": "https://recipient.example.com",
"nonce": "wrmBRkKtXjQ"
}
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": "eyJhbGciOiJCQlMtUFJPT0YiLCJhdWQiOiJodHRwczovL3JlY2
lwaWVudC5leGFtcGxlLmNvbSIsIm5vbmNlIjoid3JtQlJrS3RYalEifQ",
"issuer": "eyJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRu
RXhSMERValU4IiwiYWxnIjoiQkJTIn0",
"payloads": [
"MTcxNDUyMTYwMA",
"MTcxNzE5OTk5OQ",
"IkRvZSI",
"IkpheSI",
null,
null,
null
],
"proof": "q4wPYiFH2L4HlfYZhyBENT2fvgIkc78kgN5R1hR5kkDRET60ropZZtjhr
yYGj9XMkxAlb8G1oYWBLHfxNmGpBXSAE0tqg1lr64YtouG8xghzgJAwLRLMXdH
ElCITvRKpl2SjP5m27xwknU3wPaMVoWMP4JMwV8eFm1Ry-hm3EQ4fOqU7CvIk_
EA2nlM0RMLiU27m4P4Uw8Bdit9wskvvExbsMJ40BqwoAfec4qARLeEtAEBwgix
1hJBkMcMmodhGo-RmWYGwO-lN-r4b0NFRoQWbiMG_xcEh_ZbY1GTelA2zq6IaN
kR1QEt-5R7dB32_Fm1Jt70m8SwQYexuWgGsRE8aor8mZmUnFibuH7KLOBME3I5
98L1cVAUSDkrU1FxoCUII2_W_Kx4ExE-s8F5iUwUaPQMv05bjSWWgdBvudmD2C
mHEE39aaCg4kE8_vnTQNuXEEYgfOv7toxYs8yb5MjXRtuoXlEP5z2zjHSwiAkE
"
}
eyJhbGciOiJCQlMtUFJPT0YiLCJhdWQiOiJodHRwczovL3JlY2lwaWVudC5leGFtcGxlL mNvbSIsIm5vbmNlIjoid3JtQlJrS3RYalEifQ.eyJraWQiOiJIamZjcHlqdVpRLU84WWU yaFFuTmJUOVJiYm5yb2JwdGRuRXhSMERValU4IiwiYWxnIjoiQkJTIn0.MTcxNDUyMTYw MA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.q4wPYiFH2L4HlfYZhyBENT2fvgIkc78k gN5R1hR5kkDRET60ropZZtjhryYGj9XMkxAlb8G1oYWBLHfxNmGpBXSAE0tqg1lr64Yto uG8xghzgJAwLRLMXdHElCITvRKpl2SjP5m27xwknU3wPaMVoWMP4JMwV8eFm1Ry-hm3EQ 4fOqU7CvIk_EA2nlM0RMLiU27m4P4Uw8Bdit9wskvvExbsMJ40BqwoAfec4qARLeEtAEB wgix1hJBkMcMmodhGo-RmWYGwO-lN-r4b0NFRoQWbiMG_xcEh_ZbY1GTelA2zq6IaNkR1 QEt-5R7dB32_Fm1Jt70m8SwQYexuWgGsRE8aor8mZmUnFibuH7KLOBME3I598L1cVAUSD krU1FxoCUII2_W_Kx4ExE-s8F5iUwUaPQMv05bjSWWgdBvudmD2CmHEE39aaCg4kE8_vn TQNuXEEYgfOv7toxYs8yb5MjXRtuoXlEP5z2zjHSwiAkE
The following example uses the MAC-H256 algorithm.¶
This is the Signer's stable private key in the JWK format:¶
{
"crv": "P-256",
"kty": "EC",
"x": "ONebN43-G5DOwZX6jCVpEYEe0bYd5WDybXAG0sL3iDA",
"y": "b0MHuYfSxu3Pj4DAyDXabAc0mPjpB1worEpr3yyrft4",
"d": "jnE0-9YvxQtLJEKcyUHU6HQ3Y9nSDnh0NstYJFn7RuI"
}
This is the Signer's generated Shared Secret:¶
[100, 109, 91, 184, 139, 20, 107, 86, 1, 252, 86, 159, 126, 251, 228, 4, 35, 177, 75, 96, 11, 205, 144, 189, 42, 95, 135, 170, 107, 58, 99, 142]
This is the Holder's presentation private key in the JWK format:¶
{
"crv": "P-256",
"kty": "EC",
"x": "oB1TPrE_QJIL61fUOOK5DpKgd8j2zbZJtqpILDTJX6I",
"y": "3JqnrkucLobkdRuOqZXOP9MMlbFyenFOLyGlG-FPACM",
"d": "AvyDPl1I4xwjrI2iEOi6DxM9ipJe_h_VUN5OvoKvvW8"
}
The first MAC is generated using the key issuer_header and the base64url-encoded issuer protected header, resulting in this octet array:¶
[140, 88, 59, 30, 127, 113, 27, 237, 78, 200, 182, 114, 94, 123, 198, 128, 102, 232, 178, 88, 252, 248, 57, 2, 231, 19, 145, 8, 160, 197, 66, 166]
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 the input:¶
[ [180, 129, 55, 94, 125, 158, 179, 245, 30, 199, 148, 60, 184, 28, 197, 123, 231, 232, 95, 91, 65, 74, 38, 242, 253, 96, 67, 44, 40, 220, 250, 4], [143, 172, 182, 156, 184, 138, 228, 172, 215, 26, 175, 137, 137, 25, 159, 141, 213, 12, 214, 29, 231, 200, 13, 94, 116, 22, 41, 115, 72, 214, 57, 98], [144, 73, 77, 66, 230, 187, 217, 186, 246, 41, 138, 25, 39, 203, 101, 76, 156, 161, 244, 130, 203, 166, 184, 154, 7, 4, 218, 84, 168, 199, 36, 245], [70, 55, 182, 105, 101, 130, 254, 234, 68, 224, 219, 97, 119, 98, 244, 33, 43, 55, 148, 238, 225, 177, 101, 160, 49, 246, 109, 155, 242, 236, 21, 138] ]
The first payload is the string "Doe" with the octet sequence of [ 34, 68, 111, 101, 34 ] and base64url-encoded as IkRvZSI.¶
The second payload is the string "Jay" with the octet sequence of [ 34, 74, 97, 121, 34 ] and base64url-encoded as IkpheSI.¶
The third payload is the string "jaydoe@example.org" with the octet sequence of [ 34, 106, 97, 121, 100, 111, 101, 64, 101, 120, 97, 109, 112, 108, 101, 46, 111, 114, 103, 34 ] and base64url-encoded as ImpheWRvZUBleGFtcGxlLm9yZyI.¶
The fourth payload is the string 42 with the octet sequence of [ 52, 50 ] and base64url-encoded as NDI.¶
A MAC is generated for each payload using the generated key for its given index, resulting in an array of MACs:¶
[ [156, 53, 90, 125, 139, 226, 60, 168, 100, 220, 79, 255, 8, 87, 28, 220, 237, 112, 161, 91, 39, 68, 137, 203, 92, 243, 16, 116, 64, 129, 61, 172], [239, 17, 12, 35, 111, 129, 51, 87, 43, 86, 234, 38, 89, 149, 169, 157, 33, 104, 81, 246, 190, 154, 74, 195, 194, 158, 50, 208, 203, 203, 249, 237], [162, 174, 12, 27, 190, 250, 112, 1, 139, 177, 49, 124, 110, 201, 83, 233, 14, 109, 60, 253, 121, 184, 126, 121, 26, 138, 5, 214, 97, 96, 216, 80], [61, 109, 78, 172, 255, 189, 67, 83, 247, 65, 234, 128, 30, 47, 145, 70, 129, 26, 41, 41, 78, 4, 151, 230, 232, 127, 135, 230, 14, 208, 178, 50] ]
Concatenating the issuer protected header MAC with the array of payload MACs produces a single octet array that is signed using the issuer's stable key, resulting in the following signature:¶
[120, 172, 15, 230, 138, 230, 150, 139, 241, 196, 79, 134, 122, 43, 149, 11, 253, 104, 58, 199, 49, 87, 32, 64, 237, 50, 86, 155, 153, 58, 63, 116, 245, 130, 136, 197, 164, 207, 232, 238, 106, 171, 246, 98, 149, 254, 22, 1, 114, 187, 233, 168, 116, 173, 211, 208, 234, 245, 76, 238, 143, 157, 83, 202]
The original shared secret octet string is then concatenated to the end of the issuer signature octet string and the result is base64url-encoded as the issuer's proof value.¶
The final issued JWP in JSON serialization is:¶
{
"payloads": [
"IkRvZSI",
"IkpheSI",
"ImpheWRvZUBleGFtcGxlLm9yZyI",
"NDI"
],
"issuer": "eyJpc3MiOiJodHRwczovL2lzc3Vlci50bGQiLCJjbGFpbXMiOlsiZmF
taWx5X25hbWUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZ2UiXSwidHlwIjoiSlBUI
iwicGp3ayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwieCI6Im9CMVRQckVfUUp
JTDYxZlVPT0s1RHBLZ2Q4ajJ6YlpKdHFwSUxEVEpYNkkiLCJ5IjoiM0pxbnJrdWNMb
2JrZFJ1T3FaWE9QOU1NbGJGeWVuRk9MeUdsRy1GUEFDTSJ9LCJhbGciOiJNQUMtSDI
1NiJ9",
"proof": [
"eKwP5ormlovxxE-GeiuVC_1oOscxVyBA7TJWm5k6P3T1gojFpM_o7mqr9mKV_hYB
crvpqHSt09Dq9Uzuj51TymRtW7iLFGtWAfxWn3775AQjsUtgC82QvSpfh6prOmOO"
]
}
The same JWP in compact serialization:¶
eyJpc3MiOiJodHRwczovL2lzc3Vlci50bGQiLCJjbGFpbXMiOlsiZmFtaWx5X25hbWUi LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZ2UiXSwidHlwIjoiSlBUIiwicGp3ayI6eyJj cnYiOiJQLTI1NiIsImt0eSI6IkVDIiwieCI6Im9CMVRQckVfUUpJTDYxZlVPT0s1RHBL Z2Q4ajJ6YlpKdHFwSUxEVEpYNkkiLCJ5IjoiM0pxbnJrdWNMb2JrZFJ1T3FaWE9QOU1N bGJGeWVuRk9MeUdsRy1GUEFDTSJ9LCJhbGciOiJNQUMtSDI1NiJ9.IkRvZSI~IkpheSI ~ImpheWRvZUBleGFtcGxlLm9yZyI~NDI.eKwP5ormlovxxE-GeiuVC_1oOscxVyBA7TJ Wm5k6P3T1gojFpM_o7mqr9mKV_hYBcrvpqHSt09Dq9Uzuj51TymRtW7iLFGtWAfxWn37 75AQjsUtgC82QvSpfh6prOmOO
Next, we show the presentation of the JWP with selective disclosure.¶
We start with this presentation header using a nonce provided by the Verifier:¶
{
"nonce": "uTEB371l1pzWJl7afB0wi0HWUNk1Le-bComFLxa8K-s"
}
When signed with the holder's presentation key, the resulting signature octets are:¶
[126, 134, 175, 2, 165, 12, 103, 11, 116, 72, 94, 228, 240, 142, 107, 195, 198, 238, 218, 203, 63, 198, 105, 175, 1, 69, 182, 5, 204, 239, 35, 149, 85, 55, 4, 169, 109, 243, 88, 213, 12, 1, 167, 235, 222, 17, 232, 118, 110, 111, 47, 165, 102, 142, 0, 1, 226, 117, 143, 125, 132, 62, 231, 145]
Then by applying selective disclosure of only the given name and age claims (family name and email hidden, payload array indexes 0 and 2), the holder builds a mixed array of either the payload key (if disclosed) or MAC (if hidden):¶
[ [156, 53, 90, 125, 139, 226, 60, 168, 100, 220, 79, 255, 8, 87, 28, 220, 237, 112, 161, 91, 39, 68, 137, 203, 92, 243, 16, 116, 64, 129, 61, 172], [143, 172, 182, 156, 184, 138, 228, 172, 215, 26, 175, 137, 137, 25, 159, 141, 213, 12, 214, 29, 231, 200, 13, 94, 116, 22, 41, 115, 72, 214, 57, 98], [162, 174, 12, 27, 190, 250, 112, 1, 139, 177, 49, 124, 110, 201, 83, 233, 14, 109, 60, 253, 121, 184, 126, 121, 26, 138, 5, 214, 97, 96, 216, 80], [70, 55, 182, 105, 101, 130, 254, 234, 68, 224, 219, 97, 119, 98, 244, 33, 43, 55, 148, 238, 225, 177, 101, 160, 49, 246, 109, 155, 242, 236, 21, 138] ]
The final presented proof value is generated by concatenating first the presentation header signature octet string, followed by the issuer signature octet string, then followed by the mixed array of keys and MACs:¶
[126, 134, 175, 2, 165, 12, 103, 11, 116, 72, 94, 228, 240, 142, 107, 195, 198, 238, 218, 203, 63, 198, 105, 175, 1, 69, 182, 5, 204, 239, 35, 149, 85, 55, 4, 169, 109, 243, 88, 213, 12, 1, 167, 235, 222, 17, 232, 118, 110, 111, 47, 165, 102, 142, 0, 1, 226, 117, 143, 125, 132, 62, 231, 145, 120, 172, 15, 230, 138, 230, 150, 139, 241, 196, 79, 134, 122, 43, 149, 11, 253, 104, 58, 199, 49, 87, 32, 64, 237, 50, 86, 155, 153, 58, 63, 116, 245, 130, 136, 197, 164, 207, 232, 238, 106, 171, 246, 98, 149, 254, 22, 1, 114, 187, 233, 168, 116, 173, 211, 208, 234, 245, 76, 238, 143, 157, 83, 202, 156, 53, 90, 125, 139, 226, 60, 168, 100, 220, 79, 255, 8, 87, 28, 220, 237, 112, 161, 91, 39, 68, 137, 203, 92, 243, 16, 116, 64, 129, 61, 172, 143, 172, 182, 156, 184, 138, 228, 172, 215, 26, 175, 137, 137, 25, 159, 141, 213, 12, 214, 29, 231, 200, 13, 94, 116, 22, 41, 115, 72, 214, 57, 98, 162, 174, 12, 27, 190, 250, 112, 1, 139, 177, 49, 124, 110, 201, 83, 233, 14, 109, 60, 253, 121, 184, 126, 121, 26, 138, 5, 214, 97, 96, 216, 80, 70, 55, 182, 105, 101, 130, 254, 234, 68, 224, 219, 97, 119, 98, 244, 33, 43, 55, 148, 238, 225, 177, 101, 160, 49, 246, 109, 155, 242, 236, 21, 138]
The resulting presented JWP in JSON serialization is:¶
{
"payloads": [
null,
"IkpheSI",
null,
"NDI"
],
"issuer": "eyJpc3MiOiJodHRwczovL2lzc3Vlci50bGQiLCJjbGFpbXMiOlsiZmF
taWx5X25hbWUiLCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZ2UiXSwidHlwIjoiSlBUI
iwicGp3ayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwieCI6Im9CMVRQckVfUUp
JTDYxZlVPT0s1RHBLZ2Q4ajJ6YlpKdHFwSUxEVEpYNkkiLCJ5IjoiM0pxbnJrdWNMb
2JrZFJ1T3FaWE9QOU1NbGJGeWVuRk9MeUdsRy1GUEFDTSJ9LCJhbGciOiJNQUMtSDI
1NiJ9",
"proof": [
"foavAqUMZwt0SF7k8I5rw8bu2ss_xmmvAUW2BczvI5VVNwSpbfNY1QwBp-veEeh2
bm8vpWaOAAHidY99hD7nkXisD-aK5paL8cRPhnorlQv9aDrHMVcgQO0yVpuZOj909
YKIxaTP6O5qq_Zilf4WAXK76ah0rdPQ6vVM7o-dU8qcNVp9i-I8qGTcT_8IVxzc7X
ChWydEictc8xB0QIE9rI-stpy4iuSs1xqviYkZn43VDNYd58gNXnQWKXNI1jlioq4
MG776cAGLsTF8bslT6Q5tPP15uH55GooF1mFg2FBGN7ZpZYL-6kTg22F3YvQhKzeU
7uGxZaAx9m2b8uwVig"
],
"presentation": "eyJub25jZSI6InVURUIzNzFsMXB6V0psN2FmQjB3aTBIV1VOaz
FMZS1iQ29tRkx4YThLLXMifQ"
}
The same JWP in compact serialization:¶
eyJpc3MiOiJodHRwczovL2lzc3Vlci50bGQiLCJjbGFpbXMiOlsiZmFtaWx5X25hbWUi LCJnaXZlbl9uYW1lIiwiZW1haWwiLCJhZ2UiXSwidHlwIjoiSlBUIiwicGp3ayI6eyJj cnYiOiJQLTI1NiIsImt0eSI6IkVDIiwieCI6Im9CMVRQckVfUUpJTDYxZlVPT0s1RHBL Z2Q4ajJ6YlpKdHFwSUxEVEpYNkkiLCJ5IjoiM0pxbnJrdWNMb2JrZFJ1T3FaWE9QOU1N bGJGeWVuRk9MeUdsRy1GUEFDTSJ9LCJhbGciOiJNQUMtSDI1NiJ9.eyJub25jZSI6InV URUIzNzFsMXB6V0psN2FmQjB3aTBIV1VOazFMZS1iQ29tRkx4YThLLXMifQ.~IkpheSI ~~NDI.foavAqUMZwt0SF7k8I5rw8bu2ss_xmmvAUW2BczvI5VVNwSpbfNY1QwBp-veEe h2bm8vpWaOAAHidY99hD7nkXisD-aK5paL8cRPhnorlQv9aDrHMVcgQO0yVpuZOj909Y KIxaTP6O5qq_Zilf4WAXK76ah0rdPQ6vVM7o-dU8qcNVp9i-I8qGTcT_8IVxzc7XChWy dEictc8xB0QIE9rI-stpy4iuSs1xqviYkZn43VDNYd58gNXnQWKXNI1jlioq4MG776cA GLsTF8bslT6Q5tPP15uH55GooF1mFg2FBGN7ZpZYL-6kTg22F3YvQhKzeU7uGxZaAx9m 2b8uwVig
This work was incubated in the DIF Applied Cryptography Working Group.¶
We would like to thank Alberto Solavagione for his valuable contributions to this specification.¶
The BBS examples were generated using the library at https://github.com/mattrglobal/pairing_crypto .¶
[[ To be removed from the final specification ]]¶
-04¶
BBS-DRAFT-5 to BBS, and from BBS-PROOF-DRAFT-5 to BBS-PROOF¶
BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_¶
-03¶
-02¶
BBS-DRAFT-3 and BBS-PROOF-DRAFT-3 algorithms based on draft-irtf-cfrg-bbs-signatures-03.¶
BBS-X algorithm based on a particular implementation of earlier drafts.¶
-01¶
issuer_header and presentation_header¶
-00¶