JSON Proof Algorithms
draft-ietf-jose-json-proof-algorithms-14
| Document | Type | Active Internet-Draft (jose WG) | |
|---|---|---|---|
| Authors | Michael B. Jones , David Waite , Jeremie Miller | ||
| Last updated | 2026-07-20 | ||
| Replaces | draft-jmiller-jose-json-proof-algorithms | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| On agenda | jose at IETF-126 | ||
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-jose-json-proof-algorithms-14
jose M. Jones
Internet-Draft Self-Issued Consulting
Intended status: Standards Track D. Waite
Expires: 21 January 2027 J. Miller
Ping Identity
20 July 2026
JSON Proof Algorithms
draft-ietf-jose-json-proof-algorithms-14
Abstract
The JSON Proof Algorithms (JPA) specification registers cryptographic
algorithms and identifiers to be used with the JSON Web Proof, JSON
Web Key (JWK), and COSE specifications. It defines IANA registries
for these identifiers.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 21 January 2027.
Copyright Notice
Copyright (c) 2026 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Background . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Algorithm Basics . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Issue . . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2. Confirm . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.3. Present . . . . . . . . . . . . . . . . . . . . . . . . . 5
5.4. Verify . . . . . . . . . . . . . . . . . . . . . . . . . 6
6. JWK and COSE_Key Parameters . . . . . . . . . . . . . . . . . 6
6.1. The "proof_alg" JWK/COSE_Key Parameter . . . . . . . . . 7
7. Algorithm Specifications . . . . . . . . . . . . . . . . . . 7
7.1. Single Use . . . . . . . . . . . . . . . . . . . . . . . 7
7.1.1. JWS Algorithm . . . . . . . . . . . . . . . . . . . . 7
7.1.2. Holder Setup . . . . . . . . . . . . . . . . . . . . 8
7.1.3. Issuer Setup . . . . . . . . . . . . . . . . . . . . 8
7.1.4. Signing Payloads . . . . . . . . . . . . . . . . . . 8
7.1.5. Issuer Header . . . . . . . . . . . . . . . . . . . . 8
7.1.6. Payloads . . . . . . . . . . . . . . . . . . . . . . 9
7.1.7. Proof . . . . . . . . . . . . . . . . . . . . . . . . 9
7.1.8. Presentation Header #{presentation-header} . . . . . 9
7.1.9. Presentation . . . . . . . . . . . . . . . . . . . . 10
7.1.10. Verification of Presentation . . . . . . . . . . . . 10
7.1.11. JPA Registration . . . . . . . . . . . . . . . . . . 11
7.2. Presentation Internal Representation . . . . . . . . . . 11
7.3. BBS . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.3.1. JPA Algorithms . . . . . . . . . . . . . . . . . . . 12
7.3.2. Key Format . . . . . . . . . . . . . . . . . . . . . 13
7.3.3. Issuance . . . . . . . . . . . . . . . . . . . . . . 13
7.3.4. Issuance Proof Verification . . . . . . . . . . . . . 13
7.3.5. Presentation . . . . . . . . . . . . . . . . . . . . 13
7.3.6. Presentation Verification . . . . . . . . . . . . . . 14
7.4. Message Authentication Code . . . . . . . . . . . . . . . 14
7.4.1. Holder Setup . . . . . . . . . . . . . . . . . . . . 15
7.4.2. Issuer Setup . . . . . . . . . . . . . . . . . . . . 15
7.4.3. Combined MAC Representation . . . . . . . . . . . . . 16
7.4.4. Issuer Header . . . . . . . . . . . . . . . . . . . . 17
7.4.5. Issuer Proof . . . . . . . . . . . . . . . . . . . . 17
7.4.6. Presentation Header . . . . . . . . . . . . . . . . . 17
7.4.7. Presentation Proof . . . . . . . . . . . . . . . . . 17
7.4.8. Verification of the Presentation Proof . . . . . . . 18
7.4.9. JPA Registration . . . . . . . . . . . . . . . . . . 19
8. Security Considerations . . . . . . . . . . . . . . . . . . . 19
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
9.1. JSON Web Proof Algorithms Registry . . . . . . . . . . . 20
9.1.1. Registration Template . . . . . . . . . . . . . . . . 21
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9.1.2. Initial Registry Contents . . . . . . . . . . . . . . 22
9.1.2.1. Single-Use JWP using ES256 Algorithm . . . . . . 22
9.1.2.2. Single-Use JWP using ES384 Algorithm . . . . . . 22
9.1.2.3. Single-Use JWP using ES512 Algorithm . . . . . . 22
9.1.2.4. BBS using SHA-256 Algorithm . . . . . . . . . . . 22
9.1.2.5. MAC-H256 Algorithm . . . . . . . . . . . . . . . 23
9.1.2.6. MAC-H384 Algorithm . . . . . . . . . . . . . . . 23
9.1.2.7. MAC-H512 Algorithm . . . . . . . . . . . . . . . 23
9.1.2.8. MAC-K25519 Algorithm . . . . . . . . . . . . . . 24
9.1.2.9. MAC-K448 Algorithm . . . . . . . . . . . . . . . 24
9.1.2.10. MAC-H256K Algorithm . . . . . . . . . . . . . . . 24
9.2. JSON Web Key Parameters Registry . . . . . . . . . . . . 24
9.2.1. Registry Contents . . . . . . . . . . . . . . . . . . 24
9.3. COSE Key Common Parameters Registry . . . . . . . . . . . 25
9.3.1. Registry Contents . . . . . . . . . . . . . . . . . . 25
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
10.1. Normative References . . . . . . . . . . . . . . . . . . 25
10.2. Informative References . . . . . . . . . . . . . . . . . 26
Appendix A. JWP Examples . . . . . . . . . . . . . . . . . . . . 27
A.1. Example JSON-Serialized Single-Use JWP . . . . . . . . . 27
A.2. Example CBOR-Serialized Single-Use CPT . . . . . . . . . 32
A.3. Example BBS JWP . . . . . . . . . . . . . . . . . . . . . 36
A.4. Example MAC JWP . . . . . . . . . . . . . . . . . . . . . 38
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 42
Appendix C. Document History . . . . . . . . . . . . . . . . . . 43
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46
1. Introduction
The JSON Web Proof (JWP) [I-D.ietf-jose-json-web-proof] draft
establishes a new secure container format that supports selective
disclosure and unlinkability using Zero-Knowledge Proofs (ZKPs) or
other cryptographic algorithms.
| Editor's Note: This draft is still early and incomplete. There
| will be significant changes to the algorithms as currently defined
| here. Please do not use any of these definitions or examples for
| anything except personal experimentation and learning.
| Contributions and feedback are welcomed at https://github.com/
| ietf-wg-jose/json-web-proof (https://github.com/ietf-wg-jose/json-
| web-proof).
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2. Conventions and Definitions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
The roles of "issuer", "holder", and "verifier" are used as defined
by the VC Data Model [VC-DATA-MODEL-2.0]. The term "presentation" is
also used as defined by this source, but the term "credential" is
avoided in this specification to minimize confusion with other
definitions.
3. Terminology
The terms "JSON Web Signature (JWS)", "Base64url Encoding", "Header
Parameter", "JOSE Header", "JWS Payload", "JWS Signature", and "JWS
Protected Header" are defined by Section 2 of [RFC7515].
The terms "JSON Web Proof (JWP)", "JWP Payload", "JWP Proof", and
"JWP Header" are defined by [I-D.ietf-jose-json-web-proof].
These terms are defined by this specification:
Stable Key: An asymmetric key-pair used by an issuer that is also
shared via an out-of-band mechanism to a verifier to validate the
signature.
Issuer Ephemeral Key: An asymmetric key-pair that is generated for
one-time use by an issuer and never stored or used again outside
of the creation of a single JWP.
Holder Presentation Key: An asymmetric key-pair that is generated by
a holder and used to ensure that a presentation is not able to be
replayed by any other party.
4. Background
JWP defines a container binding together a 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.
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5. Algorithm Basics
The four principal interactions that every proof algorithm MUST
support are issue (#issue), confirm (#confirm), present (#present),
and verify (#verify).
5.1. Issue
The JWP is first created as the output of a JPA's issue operation.
Every algorithm MUST support a JSON issuer 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.
5.2. Confirm
Performed by the holder to validate that the issued JWP is correctly
formed and protected.
Each algorithm MAY support using additional input items options, such
as those sent to the issuer for issuance. After confirmation, an
algorithm MAY return a modified JWP for serialized storage without
the local state (such as with blinded payloads now unblinded).
The algorithm MUST fully verify the issued proof value against the
Issuer Header and all payloads. If given a presented JWP instead of
an issued one, the confirm process MUST return an error.
5.3. Present
Used to apply any selective disclosure choices and perform any
unlinkability transformations, as well as to show binding.
An algorithm MAY support additional input options from the requesting
party, such as for predicate proofs and verifiable computation
requests.
Every algorithm MUST support the ability to hide any or all payloads.
It MUST always include the Issuer Header unmodified in the
presentation.
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The algorithm MUST replace the issued proof value and generate a new
presented proof value. It also MUST include a new Presentation
Header that provides replay protection.
5.4. Verify
Performed by the verifier to verify the 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
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.
6. JWK and COSE_Key Parameters
For JSON Web Keys, the optional alg (algorithm) parameter identifies
the algorithm intended for use. This can reference the IANA "JSON
Web Signature and Encryption Algorithms" registry [IANA.JOSE], or be
a collision-resistant name.
To avoid the risk of collision with algorithms registered in the
"JSON Web Proof Algorithms" registry, this specification defines the
proof_alg key parameter.
For COSE_Key values, a proof_alg key parameter is likewise defined to
avoid collisions with the IANA "COSE Algorithms" registry
[IANA.COSE].
Implementations SHOULD NOT specify proof algorithms using the alg key
parameter.
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6.1. The "proof_alg" JWK/COSE_Key Parameter
The proof_alg (Proof Algorithm) key parameter is used to restrict the
algorithm that is used with the key. If this parameter is present in
the key structure, the application MUST verify that this algorithm
matches the algorithm for which the key is being used. If the
algorithms do not match, then this key object MUST NOT be used to
perform the cryptographic operation.
As a JWK parameter, the proof_alg value is a case-sensitive ASCII
string containing a StringOrURI value. The value MUST be a name
registered in the IANA "JSON Web Proof Algorithms" registry
established by this specification, or be a collision-resistant name
for a JSON Web Proof Algorithm.
As a CWK parameter, this value may also be an integer value. The
integer CBOR Label from the "JSON Web Proof Algorithms" registry
SHOULD be used when one is available.
When proof_alg is present, the alg key parameter SHOULD NOT be used.
Use of this key parameter is OPTIONAL.
7. Algorithm Specifications
This section defines how to use specific algorithms for JWPs.
7.1. 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).
7.1.1. JWS Algorithm
The Single Use algorithm uses multiple signing keys to protect the
Header as well as individual payloads of an Issued JWP. The issuer
uses a stable public key to sign each Header, and a per-JWP ephemeral
key (conveyed within the 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.
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The Issuer 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.
Issuers and holders MUST choose asymmetric signing algorithms, so
each signature can be verified without sharing secrets between the
parties.
7.1.2. Holder Setup
To support the protection of a presentation by a holder to a
verifier, the holder MUST use a Holder Presentation Key during the
issuance and the presentation of every Single Use JWP. This Holder
Presentation Key MUST be generated and used for only one JWP if
unlinkability is desired.
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 determine an appropriate holder presentation
algorithm corresponding to the holder presentation key. If the
holder and verifier cannot be assumed to know this algorithm is the
appropriate choice for a given holder presentation key, this value
MUST be conveyed in the hpa Issuer Header Parameter.
7.1.3. 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.
7.1.4. Signing Payloads
Each individual payload is signed using the selected internal
algorithm using the Ephemeral Key.
7.1.5. Issuer Header
The Issuer's Ephemeral Key MUST be included via the Issuer Ephemeral
Key Header Parameter.
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The Holder's Presentation Key MUST be included via the Holder
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 Header is signed using the appropriate internal signing
algorithm for the given fully-specified single use algorithm, using
the issuer's Stable Key.
7.1.6. Payloads
Each JWP payload is processed in order and signed using the given JWA
using the issuer's Ephemeral Key.
7.1.7. Proof
The proof value is an octet string array. The first entry is the
octet string of the Issuer Header signature, with an additional entry
for each payload signature.
7.1.8. Presentation Header #{presentation-header}
To generate a new presentation, the holder first creates a
Presentation 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 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 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 Header MUST contain the same alg Header Parameter
value as the Issuer Header. It MUST NOT contain the hpa Header
Parameter.
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7.1.9. Presentation
The holder derives a new proof as part of presentation. The holder
will also use these components to generate a presentation internal
representation (#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
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 Presentation Header, Issuer 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:
1. The issuer's signature over the Issuer Header
2. The payload signature corresponding to the second payload
3. 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 fourth 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.
7.1.10. Verification of Presentation
Verification is performed using the following steps.
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1. Check that the number of proof components is appropriate for the
number of disclosed payloads. There MUST be two more proof
components than disclosed payloads.
2. Verify the first proof component is a valid signature over Issuer
Header octets, using the issuer's stable key.
3. Extract the holder presentation key and holder presentation
algorithm (if present) from the Issuer Header.
4. Omitting the final payload component, calculate the presentation
internal representation (#presentation-internal-representation).
5. 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. For each remaining proof component, verify they form a valid
signature over each disclosed payload in sequence, using the
issuer's ephemeral key.
7.1.11. 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".
7.2. 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:
1. 0x84 5B
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2. The length and octets of the Presentation Header
3. 0x5B
4. The length and octets of the Issuer Header
5. 0x9B
6. The number of payload slots in the issued message
7. For each payload representation:
* If the payload is being omitted, the value 0xF6
* Otherwise:
1. 0x5B
2. The length and octets of the payload
8. 0x9B
9. The number of proof components as specified by the algorithm
10. For each proof component, append:
1. 0x5B
2. The length and octets of the proof component
7.3. 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.
7.3.1. JPA Algorithms
The BBS algorithm corresponds to a cipher suite identifier of
BBS_BLS12381G1_XMD:SHA-256_SSWU_RO_.
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7.3.2. 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 of [I-D.irtf-cfrg-bbs-signatures]. 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.
7.3.3. 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 Header octets
as header, and the array of payload octet string as messages.
The octets resulting from this operation form a single octet string
in the issuance proof array, to be used along with the Header and
payloads to serialize the JWP.
7.3.4. 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 Header octets as header and the array of payload
octets as messages.
7.3.5. 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
Header as header, the issuance proof as signature, the issuance
payloads as messages, and the holder's Presentation 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.
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The output of this operation is the presentation proof, as a single
octet string.
Presentation serialization leverages the two Headers and presentation
proof, along with the disclosed payloads. Encoding of disclosed and
omitted payload slots follows the JWP serialization rules defined in
[I-D.ietf-jose-json-web-proof].
7.3.6. Presentation Verification
Verification of a presentation is done by the verifier using the
ProofVerify operation from Section 3.5.4 of
[I-D.irtf-cfrg-bbs-signatures].
This operation utilizes the issuer's public key as PK, the Issuer
Header as header, the issuance proof as signature, the holder's
Presentation 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.
If ProofVerify returns false, the presented JWP is invalid and the
verifier rejects it.
7.4. Message Authentication Code
The Message Authentication Code (MAC) JPA uses a MAC to both generate
ephemeral 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 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 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
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cryptographic MAC method such as HMAC [RFC2104] or KMAC
(https://nvlpubs.nist.gov/nistpubs/SpecialPublications/
NIST.SP.800-185.pdf). It uses traditional public key-based
signatures to verify the authenticity of the issuer and holder.
7.4.1. Holder Setup
To support the protection of a presentation by a holder to a
verifier, the holder MUST use a Holder Presentation Key during the
issuance and the presentation of every MAC JWP. This Holder
Presentation Key MUST be generated and used for only one JWP if
unlinkability is desired.
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 holder's presentation key MUST be included in the Issuer Header
using the Holder Presentation Key Header Parameter.
The issuer MUST determine an appropriate holder presentation
algorithm corresponding to the holder presentation key. If the
holder and verifier cannot be assumed to know this algorithm is the
appropriate choice for a given holder presentation key, this value
MUST be conveyed in the hpa Issuer Header Parameter.
7.4.2. 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 with 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.
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7.4.3. Combined MAC Representation
The combined MAC representation is a single octet string representing
the MAC values of the Issuer 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 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 derive 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:
1. 0x82 67 70 61 79 6C 6F 61 64 1B
2. 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 MAC Presentation Proof (#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.
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The binary representation is created by appending data into a single
octet string in the following order:
1. 0x82 5B
2. The length and octets of the Issuer Header
3. 0x9B
4. The number of payload slots in the issued JWP
5. For each payload representation:
1. 0x5B
2. The length and value of the per payload MAC
7.4.4. Issuer Header
The Holder's Presentation Key MUST be included via the Holder
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.
7.4.5. 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.
7.4.6. Presentation Header
See the Presentation Header (#presentation-header) section given for
Single Use algorithms.
7.4.7. 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.
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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 (#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 Presentation Header, Issuer Header, payload slots (distinguishing
which are being disclosed) and above proof components are inputs to
determine the presentation internal representation (#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.
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.
7.4.8. Verification of the Presentation Proof
Verification is performed using the following steps.
1. Check the number of proof components is appropriate for the
number of disclosed payloads. There MUST be two more proof
components than disclosed payloads.
2. Using the fully-specified MAC algorithm in use, use the Issuer
Header, disclosed payloads, and the proof components
corresponding to the payloads to regenerate the Combined MAC
Representation.
3. Verify the first proof component is a valid signature over the
Issuer Header octets, using the issuer's stable key.
4. Extract the holder presentation key and holder presentation
algorithm (if present) from the Issuer Header.
5. Omitting the final payload component, calculate the presentation
internal representation (#presentation-internal-representation).
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6. 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.
7.4.9. 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. Security Considerations
| Editor's Note: This will follow once the algorithms defined here
| have become more stable.
* Data minimization of the proof value
* Unlinkability of the Header contents
9. IANA Considerations
The following registration procedure is used for all the registries
established by this specification.
Values are registered on a Specification Required [RFC8126] basis
after a three-week review period on the jose-reg-review@ietf.org
(mailto: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").
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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 (mailto: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, 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.
9.1. JSON Web Proof Algorithms Registry
This specification establishes the IANA "JSON Web Proof Algorithms"
registry, under the "JSON Object Signing and Encryption (JOSE)"
registry group. The registry records values of the JWP alg
(algorithm) Header Parameter. 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.
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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.
9.1.1. 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 of 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 IETF Stream 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
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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.
9.1.2. Initial Registry Contents
9.1.2.1. 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 7.1.11 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.2. 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 7.1.11 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.3. 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 7.1.11 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.4. BBS using SHA-256 Algorithm
* Algorithm Name: BBS using SHA-256
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* Algorithm JSON Label: BBS
* Algorithm CBOR Label: 4
* Algorithm Description: Corresponds to a cipher suite 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 7.3.1 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.5. 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 7.4.9 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.6. 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 7.4.9 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.7. 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 7.4.9 of this specification
* Algorithm Analysis Documents(s): n/a
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9.1.2.8. 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 7.4.9 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.9. 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 7.4.9 of this specification
* Algorithm Analysis Documents(s): n/a
9.1.2.10. 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 7.4.9 of this specification
* Algorithm Analysis Documents(s): n/a
9.2. JSON Web Key Parameters Registry
This section registers the following JWK parameter in the IANA "JSON
Web Key Parameters" registry [IANA.JOSE] established by Section 8.1
of [RFC7517].
9.2.1. Registry Contents
* Parameter Name: proof_alg
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* Parameter Description: JSON Web Proof algorithm associated with
the key
* Used with "kty" Value(s): *
* Parameter Information Class: Public
* Change Controller: IESG
* Specification Document(s): Section 6.1 of this specification
9.3. COSE Key Common Parameters Registry
This section registers the following COSE_Key parameter in the IANA
"COSE Key Common Parameters" registry [IANA.COSE] established by
Section 11.2 of [RFC9052].
9.3.1. Registry Contents
* Name: proof_alg
* Label: TBD (requested assignment 7)
* CBOR Type: int / tstr
* Value Registry: JSON Web Proof Algorithms
* Description: JSON Web Proof algorithm associated with the key
* Reference: Section 6.1 of this specification
[RFC-EDITOR: The temporary development label for this COSE_Key
parameter is 7CPA, following [I-D.bormann-cbor-draft-numbers].
Please replace 7CPA with the final assigned value and remove this
note before publication.]
10. References
10.1. Normative References
[I-D.ietf-cose-bls-key-representations]
Looker, T. and M. B. Jones, "Barreto-Lynn-Scott Elliptic
Curve Key Representations for JOSE and COSE", Work in
Progress, Internet-Draft, draft-ietf-cose-bls-key-
representations-08, 4 November 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-cose-
bls-key-representations-08>.
[I-D.ietf-jose-json-web-proof]
Waite, D., Jones, M. B., and J. Miller, "JSON Web Proof",
Work in Progress, Internet-Draft, draft-ietf-jose-json-
web-proof-latest, <https://datatracker.ietf.org/doc/html/
draft-ietf-jose-json-web-proof>.
[I-D.irtf-cfrg-bbs-signatures]
Looker, T., Kalos, V., Whitehead, A., and M. Lodder, "The
BBS Signature Scheme", Work in Progress, Internet-Draft,
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draft-irtf-cfrg-bbs-signatures-10, 8 January 2026,
<https://datatracker.ietf.org/doc/html/draft-irtf-cfrg-
bbs-signatures-10>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7515] Jones, M., Bradley, J., and N. Sakimura, "JSON Web
Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
2015, <https://www.rfc-editor.org/info/rfc7515>.
[RFC7517] Jones, M., "JSON Web Key (JWK)", RFC 7517,
DOI 10.17487/RFC7517, May 2015,
<https://www.rfc-editor.org/info/rfc7517>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9052] Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", STD 96, RFC 9052,
DOI 10.17487/RFC9052, August 2022,
<https://www.rfc-editor.org/info/rfc9052>.
[VC-DATA-MODEL-2.0]
Sporny, M., Jr, T. T., Herman, I., Cohen, G., and M. B.
Jones, "Verifiable Credentials Data Model v2.0", 15 May
2025, <https://www.w3.org/TR/vc-data-model-2.0>.
10.2. Informative References
[I-D.bormann-cbor-draft-numbers]
Bormann, C., "CBOR: Code Point Allocation and Assigned
Numbers", Work in Progress, Internet-Draft, draft-bormann-
cbor-draft-numbers-latest,
<https://datatracker.ietf.org/doc/html/draft-bormann-cbor-
draft-numbers>.
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[I-D.ietf-cbor-edn-literals]
Bormann, C., "Concise Diagnostic Notation (CDN)", Work in
Progress, Internet-Draft, draft-ietf-cbor-edn-literals-27,
20 July 2026, <https://datatracker.ietf.org/doc/html/
draft-ietf-cbor-edn-literals-27>.
[I-D.ietf-spice-oidc-cwt]
Maldant, B. and M. B. Jones, "OpenID Connect Standard
Claims Registration for CBOR Web Tokens", Work in
Progress, Internet-Draft, draft-ietf-spice-oidc-cwt-05, 2
March 2026, <https://datatracker.ietf.org/doc/html/draft-
ietf-spice-oidc-cwt-05>.
[IANA.COSE]
IANA, "CBOR Object Signing and Encryption",
<https://www.iana.org/assignments/cose>.
[IANA.JOSE]
IANA, "JSON Object Signing and Encryption",
<https://www.iana.org/assignments/jose>.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997,
<https://www.rfc-editor.org/info/rfc2104>.
[RFC7518] Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
DOI 10.17487/RFC7518, May 2015,
<https://www.rfc-editor.org/info/rfc7518>.
[RFC8392] Jones, M., Wahlstroem, E., Erdtman, S., and H. Tschofenig,
"CBOR Web Token (CWT)", RFC 8392, DOI 10.17487/RFC8392,
May 2018, <https://www.rfc-editor.org/info/rfc8392>.
Appendix A. JWP Examples
This section provides several sample JWPs, using algorithms defined
above. The private keys are also included 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.
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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:
{
"crv": "P-256",
"d": "DK-sovUBcervl5QDJKW6Ujwq51ICSfkSSRdcd6fSpOE",
"kty": "EC",
"x": "xs_KueKqEaJbGljUbyYH76P5Z94HOkafqrD1BGKnijU",
"y": "BHbl5x2yWAOufTsB5EHetmBGl_c1TjzbtoTL3TZgvPk"
}
Figure 1: Issuer Private Key (ES256 in JWK)
This is the ephemeral private key used in this example in the JWK
format:
{
"crv": "P-256",
"d": "kK_tJMtwmY15FvJfAJBceewzYibZhh1Uz9jQWUHEDfc",
"kty": "EC",
"x": "9zZSaMP_X_NFOm1Dinx_Ek0JQCi1Q62wyJYW_4Ge8J0",
"y": "niWuxuD82iGuZ9fHHtvaruTuwebTqlPoiltsLNcv5LM"
}
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:
{
"crv": "P-256",
"d": "sYGORNvEEUbzbOUsPVAxYPK0Nh-Pt86ToMGp-GNA4Rg",
"kty": "EC",
"x": "xP_7tI1acMDwEVxUp-XtCVxNTkzfPKUXYH-1w8YsfnU",
"y": "PkCV1HmrruCRjM44DAbdb_1opv03xAEMZeKbih_CEJQ"
}
Figure 3: Holder Presentation Private Key (ES256 in JWK)
The 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.
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{
"alg": "SU-ES256",
"claims": [
"iat",
"exp",
"family_name",
"given_name",
"email",
"address",
"age_over_21"
],
"hpa": "ES256",
"hpk": {
"crv": "P-256",
"kty": "EC",
"x": "xP_7tI1acMDwEVxUp-XtCVxNTkzfPKUXYH-1w8YsfnU",
"y": "PkCV1HmrruCRjM44DAbdb_1opv03xAEMZeKbih_CEJQ"
},
"iek": {
"crv": "P-256",
"kty": "EC",
"x": "9zZSaMP_X_NFOm1Dinx_Ek0JQCi1Q62wyJYW_4Ge8J0",
"y": "niWuxuD82iGuZ9fHHtvaruTuwebTqlPoiltsLNcv5LM"
},
"iss": "https://issuer.example",
"typ": "JPT"
}
Figure 4: Issuer Header (SU-ES256, JSON)
eyJhbGciOiJTVS1FUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbHlfbmFtZ
SIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJdLCJocG
EiOiJFUzI1NiIsImhwayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwieCI6InhQXzd
0STFhY01Ed0VWeFVwLVh0Q1Z4TlRremZQS1VYWUgtMXc4WXNmblUiLCJ5IjoiUGtDVjFI
bXJydUNSak00NERBYmRiXzFvcHYwM3hBRU1aZUtiaWhfQ0VKUSJ9LCJpZWsiOnsiY3J2I
joiUC0yNTYiLCJrdHkiOiJFQyIsIngiOiI5elpTYU1QX1hfTkZPbTFEaW54X0VrMEpRQ2
kxUTYyd3lKWVdfNEdlOEowIiwieSI6Im5pV3V4dUQ4MmlHdVo5ZkhIdHZhcnVUdXdlYlR
xbFBvaWx0c0xOY3Y1TE0ifSwiaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsInR5
cCI6IkpQVCJ9
Figure 5: Encoded Issuer Header (SU-ES256, JSON, encoded)
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The Single Use algorithm utilizes multiple individual JWS Signatures.
Each signature value is generated by creating a JWS with a single
Header with the associated alg value. In this example, the fixed
Header used for each JWS is the serialized JSON Object
{"alg":"ES256"}. This 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",
{
"country": "USA",
"formatted": "1234 Main St.\nAnytown, CA 12345\nUSA",
"locality": "Anytown",
"postal_code": 12345,
"region": "CA",
"street_address": "1234 Main St."
},
true
]
Figure 6: Issuer payloads (JSON, as array)
The compact serialization of the same JPT is:
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eyJhbGciOiJTVS1FUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbHlfbmFtZ
SIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJdLCJocG
EiOiJFUzI1NiIsImhwayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwieCI6InhQXzd
0STFhY01Ed0VWeFVwLVh0Q1Z4TlRremZQS1VYWUgtMXc4WXNmblUiLCJ5IjoiUGtDVjFI
bXJydUNSak00NERBYmRiXzFvcHYwM3hBRU1aZUtiaWhfQ0VKUSJ9LCJpZWsiOnsiY3J2I
joiUC0yNTYiLCJrdHkiOiJFQyIsIngiOiI5elpTYU1QX1hfTkZPbTFEaW54X0VrMEpRQ2
kxUTYyd3lKWVdfNEdlOEowIiwieSI6Im5pV3V4dUQ4MmlHdVo5ZkhIdHZhcnVUdXdlYlR
xbFBvaWx0c0xOY3Y1TE0ifSwiaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsInR5
cCI6IkpQVCJ9.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZU
BleGFtcGxlLm9yZyI~eyJjb3VudHJ5IjoiVVNBIiwiZm9ybWF0dGVkIjoiMTIzNCBNYWl
uIFN0LlxuQW55dG93biwgQ0EgMTIzNDVcblVTQSIsImxvY2FsaXR5IjoiQW55dG93biIs
InBvc3RhbF9jb2RlIjoxMjM0NSwicmVnaW9uIjoiQ0EiLCJzdHJlZXRfYWRkcmVzcyI6I
jEyMzQgTWFpbiBTdC4ifQ~dHJ1ZQ.2hSttoVIGlLP727_737J5Srtkr8w5P4zG1QihW2J
uvob4EkqDiJ319D5TdQczv3bAqBeWtxuDOHWOhiIrYaGTw~KuiMmRW7h-2OqDCZ6R8Zn3
XQ_8youcBFxEmmXWMJyiceg6mZtEPcDTTN3l6HOE-5jzZ-G2cDl5gMjilbhGDxeQ~RSTl
0mFdKoQYMAcAzt7_3XV6lCkxVRR0rJQtgGFFujxZXFAAyGRR02Cuu7T6Fn0c8IGmySw7T
NIzcxeyEyYTlQ~1l9iFb7xjMiRjUCrnyH12Gf99LSjEOKW_Spguex4mkNdwdpET7qRZq1
siO2tWKB_Z6nIX2cTOZRhmzzjGF_m4Q~TXc80HAXqHvTUOyg990ihSMCCV8aLRyn_gyaX
6mnkHRIbjDaV-CAMLx3RhmdC3YkthnyEnaXFF5HZtmkIxGLEA~eA9uT8m3CTYttNl0_dd
XKhhh1RnVnIOE4rbMfLq7jw8PAUBXZ7o1y26gV5g7Kpghmt2Fd0N9oK2imQvtFn9bUA~b
YGxg3HjwR7O406Ne2U1O207QdOm6kF2g-N9NQtkaTFwGaEz_1U5uonRPylkR1xlmvKvt2
rMTqiYf-_-pSYdmg~nMkClCSY1g-U5YMW473p2UKm7TFYs3bpjWUrAFCcaC0U958yRXmH
S0nY0iFIfqVkTUxqhrvq55VV4r8xKsp6fQ
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": "Kbyx9Mlh-XUgbOdam1vR-dl4WK13Ltn6y7nfvFUQKKM"
}
Figure 8: Presentation Header (SU-ES256, JSON)
eyJhbGciOiJTVS1FUzI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJLYnl4OU1saC1YVWdiT2RhbTF2Ui1kbDRXSzEzTHRuNnk3bmZ2Rl
VRS0tNIn0
Figure 9: Presentation Header (SU-ES256, JSON, Base64url-Encoded)
We apply selective disclosure of only the given name and age_over_21
claims (family name, email, and address hidden), and remove the proof
components corresponding to these entries.
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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
29tIiwibm9uY2UiOiJLYnl4OU1saC1YVWdiT2RhbTF2Ui1kbDRXSzEzTHRuNnk3bmZ2Rl
VRS0tNIn0.eyJhbGciOiJTVS1FUzI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1
pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8y
MSJdLCJocGEiOiJFUzI1NiIsImhwayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwie
CI6InhQXzd0STFhY01Ed0VWeFVwLVh0Q1Z4TlRremZQS1VYWUgtMXc4WXNmblUiLCJ5Ij
oiUGtDVjFIbXJydUNSak00NERBYmRiXzFvcHYwM3hBRU1aZUtiaWhfQ0VKUSJ9LCJpZWs
iOnsiY3J2IjoiUC0yNTYiLCJrdHkiOiJFQyIsIngiOiI5elpTYU1QX1hfTkZPbTFEaW54
X0VrMEpRQ2kxUTYyd3lKWVdfNEdlOEowIiwieSI6Im5pV3V4dUQ4MmlHdVo5ZkhIdHZhc
nVUdXdlYlRxbFBvaWx0c0xOY3Y1TE0ifSwiaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbX
BsZSIsInR5cCI6IkpQVCJ9.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~~IkpheSI~~~dHJ1Z
Q.2hSttoVIGlLP727_737J5Srtkr8w5P4zG1QihW2Juvob4EkqDiJ319D5TdQczv3bAqB
eWtxuDOHWOhiIrYaGTw~KuiMmRW7h-2OqDCZ6R8Zn3XQ_8youcBFxEmmXWMJyiceg6mZt
EPcDTTN3l6HOE-5jzZ-G2cDl5gMjilbhGDxeQ~RSTl0mFdKoQYMAcAzt7_3XV6lCkxVRR
0rJQtgGFFujxZXFAAyGRR02Cuu7T6Fn0c8IGmySw7TNIzcxeyEyYTlQ~TXc80HAXqHvTU
Oyg990ihSMCCV8aLRyn_gyaX6mnkHRIbjDaV-CAMLx3RhmdC3YkthnyEnaXFF5HZtmkIx
GLEA~nMkClCSY1g-U5YMW473p2UKm7TFYs3bpjWUrAFCcaC0U958yRXmHS0nY0iFIfqVk
TUxqhrvq55VV4r8xKsp6fQ~LG1E3Q4f6K4CB2dfDao1QP0D7nBkZIPPSLh3nY3hc-hRkI
-7fRHQYf_gYZfzYFZGLj7I--DdWelDlZtqSPuUyA
| 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] (CWT) and claims from [I-D.ietf-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.
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{ / issuer 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: { / iek /
1: 2, / kty : "EC2" /
-1: 1, / crv: "P-256" /
-2: h'f7365268c3ff5ff3453a6d438a7c7f124d094028b543adb0c89616ff' +
h'819ef09d', / x /
-3: h'9e25aec6e0fcda21ae67d7c71edbdaaee4eec1e6d3aa53e88a5b6c2c' +
h'd72fe4b3' / y /
},
9: { / hpk /
1: 2, / kty: "EC2" /
-1: 1, / crv: "P-256" /
-2: h'c4fffbb48d5a70c0f0115c54a7e5ed095c4d4e4cdf3ca517607fb5c3' +
h'c62c7e75', / x /
-3: h'3e4095d479abaee0918cce380c06dd6ffd68a6fd37c4010c65e29b8a' +
h'1fc21094' / y /
},
10: -9 / hpa: "ESP256" (I-D.ietf-jose-fully-specified-algorithms TBD-9) /
}
| Figure: Issuer Header (SU-ES256, CBOR)
The payload values below are the same logical claims as in the JSON
JPT example above, represented in EDN for the CBOR-based form.
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[ / 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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8358cfa701010314057668747470733a2f2f6973737565722e6578616d706c65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| Figure: 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:
{ / holder header /
1: 1, / alg: "SU-ES256" /
6: "https://recipient.example.com", / aud /
7: h'29bcb1f4c961f975206ce75a9b5bd1f9d97858ad772ed9facbb9dfbc551028a3', / nonce /
}
| Figure: Presentation Header (SU-ES256, CBOR)
When the appropriate proof is generated, the CPT is serialized into
the following CBOR (in hex):
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845846a3010106781d68747470733a2f2f726563697069656e742e6578616d70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| 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:
{
"crv": "BLS12381G2",
"d": "NvpnjNccjwvZTsmcBO4Ntw46mzig50sfOYjeljAl8Bk",
"kty": "OKP",
"proof_alg": "BBS",
"x": "l5CqEP9LwItyq0KzEU7FVrNollmcqgUGX6v69ghb3VNRMfPP3wGg7Tk8m9VEn
edsFUKjxj35OiCTWU3w43faSmn3wenj3E52S4ifIRJgBI1JP_q_1-7TsA7Wmt
wj1Z05"
}
Figure 10: BBS private key in JWK format
There is no additional holder key necessary for presentation proofs.
For the following Issuer Header and array of payloads:
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{
"alg": "BBS",
"kid": "HjfcpyjuZQ-O8Ye2hQnNbT9RbbnrobptdnExR0DUjU8"
}
Figure 11: Example Issuer Header
These components are signed using the private issuer key previously
given, which is then representable in the following serialization:
eyJhbGciOiJCQlMiLCJraWQiOiJIamZjcHlqdVpRLU84WWUyaFFuTmJUOVJiYm5yb2Jwd
GRuRXhSMERValU4In0.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~Imph
eWRvZUBleGFtcGxlLm9yZyI~eyJjb3VudHJ5IjoiVVNBIiwiZm9ybWF0dGVkIjoiMTIzN
CBNYWluIFN0LlxuQW55dG93biwgQ0EgMTIzNDVcblVTQSIsImxvY2FsaXR5IjoiQW55dG
93biIsInBvc3RhbF9jb2RlIjoxMjM0NSwicmVnaW9uIjoiQ0EiLCJzdHJlZXRfYWRkcmV
zcyI6IjEyMzQgTWFpbiBTdC4ifQ~dHJ1ZQ.t-CcghOPDTsp5rqRS3Uxc71LnFXzeFuLln
5xL1QjofTHVe7l_0CNFuKmfxDC51uCKIjBhPEy3gmKSC3sj6I2tcDz9HmgH0iD2qSOiRt
IALk
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: 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.eyJhbGciOiJCQlMiLCJraWQiOiJIamZjcHlqdVp
RLU84WWUyaFFuTmJUOVJiYm5yb2JwdGRuRXhSMERValU4In0.MTcxNDUyMTYwMA~MTcxN
zE5OTk5OQ~IkRvZSI~IkpheSI~~~.j8Un-MjA3J3D5HN9_dC3WLgFx51MIWLc--NPxO1N
SIb7RZENkiwMo8pzHcq3uevulTEy0Ni_BqBQ6wrS19uBtfBAlsqf3boYAwroR4RIMFc7D
Ko3qhKgy_Y7A1Zt_2CIrfjEPj_PsaKCntHZRjGZs9ZA1tzvc3CyrGYlE4ssiEHU9AY_t1
eGCEro_nI8VAVhCVOyl-_GkhjstRLxACFlM8lAJ1MRrNPfIYKsMjFV5PlBkY9sab1dE5S
n7ZpQyQEl2g9jlLfYm2plGUPT4KV6mV0sWlmAT73XWQwsnc6WR_dhoL-QNLSBRgKXklDu
yN40M02Qy0SndGHx-W-rlvCD7LkoHbuKpX2GtyE6aR4EBxMsMtRZXLsfD0JzG37TfRw2F
II_BFslao_0XsWNbpUATyX5DvYB0Uvzd94a_B0eCuf-qfoLTlZIeqWZIO9kVVk3Iu1HSh
pL1vx21g7iVQM7Wo1jgkwjpcml7Nn4WGFee_s
Figure 14: Presentation JWP (BBS, JSON, Compact Serialization)
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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:
{
"crv": "P-256",
"d": "DK-sovUBcervl5QDJKW6Ujwq51ICSfkSSRdcd6fSpOE",
"kty": "EC",
"x": "xs_KueKqEaJbGljUbyYH76P5Z94HOkafqrD1BGKnijU",
"y": "BHbl5x2yWAOufTsB5EHetmBGl_c1TjzbtoTL3TZgvPk"
}
Figure 15: Issuer private key
This is the shared secret carried in the issued proof:
"btenJSeYxfYFWF_1WYcQSj5VCY-ecbfibB9Y1V9gHZo"
Figure 16: Shared Secret
This is the Holder's presentation private key in the JWK format:
{
"crv": "P-256",
"d": "sYGORNvEEUbzbOUsPVAxYPK0Nh-Pt86ToMGp-GNA4Rg",
"kty": "EC",
"x": "xP_7tI1acMDwEVxUp-XtCVxNTkzfPKUXYH-1w8YsfnU",
"y": "PkCV1HmrruCRjM44DAbdb_1opv03xAEMZeKbih_CEJQ"
}
Figure 17: Holder private key
For the following Header and array of payloads:
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{
"alg": "MAC-H256",
"claims": [
"iat",
"exp",
"family_name",
"given_name",
"email",
"address",
"age_over_21"
],
"hpa": "ES256",
"hpk": {
"crv": "P-256",
"kty": "EC",
"use": "sign",
"x": "xP_7tI1acMDwEVxUp-XtCVxNTkzfPKUXYH-1w8YsfnU",
"y": "PkCV1HmrruCRjM44DAbdb_1opv03xAEMZeKbih_CEJQ"
},
"iss": "https://issuer.example",
"typ": "JPT"
}
Figure 18: Example Issuer Header
[
1714521600,
1717199999,
"Doe",
"Jay",
"jaydoe@example.org",
{
"country": "USA",
"formatted": "1234 Main St.\nAnytown, CA 12345\nUSA",
"locality": "Anytown",
"postal_code": 12345,
"region": "CA",
"street_address": "1234 Main St."
},
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 the key and a binary value
based on the payload slot index (from zero) as input to the HMAC
operation.
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This results in the following set of derived keys:
[
"dAl1DDShaQd8JNWxtb_geTjPpdlUvhAYxhjZXQT9m78",
"ixhgL6Xok1TY8qhJQs5RpUUdwaI2UUth-c1kE_Tp9Is",
"AlsVYc-OkHzb-jjK11lXIebmaMydqDqInqVe29W2Vpo",
"sMtqZYvHga5XmI0iXfjt590DUGTkijkW2uBlcxUtNic",
"rdM7EBeXSoiWAH2LEwF29M9OfuuL6CBPy0BHe7kfhiU",
"BxMPFRpKIr2mxKh5CJh1T4uUTaR6FOUNFtViGUp2Rpg",
"5dhLeVVCb6qFOJWf3juea0t1BxQxVtfjZ60bB-Wx3-g"
]
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:
[
"pbFrro8SUA49BeLEhzFHsO0YXW1H9i2Q3Fx5zwvaGp8",
"507GVZGewdO3yNLRx3SmSDpBrOu_TIcZsNBStpxcbZ0",
"klrnMHpYlOCPR0mHqaABeajd7vLP7FPy7G-IqKCwY4s",
"jvC3hx68X9-wWetwIZAcUcpdpfO2dg0pZhUQwgTqBvo",
"LCwZOoqRRM0OePErrPelGxf0TEngY8ZjoDDi2OJLHZo",
"BJ5DQg-cWglSDDxdmXs1AD0Zkb09a32h3vCEqFdj0PI",
"d4PaY2wWPAy8xYbK4yYrnZIZAbPKIb0OYScKVd7Er5I"
]
Figure 21: Payload MAC values (Base64url-Encoded)
The Issuer 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.
[
"3JleU8_ZBjqlcsWNfq7yUFnqH3-J529Y7JPOTO-VuNQT-YgYwm9oifqsJQiibvrXLh
aUoTKkpGovV6vxd5ByHA",
"btenJSeYxfYFWF_1WYcQSj5VCY-ecbfibB9Y1V9gHZo"
]
Figure 22: Issued Proof (Base64url-Encoded)
The final issued JWP in compact serialization is:
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eyJhbGciOiJNQUMtSDI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1pbHlfbmFtZ
SIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8yMSJdLCJocG
EiOiJFUzI1NiIsImhwayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwidXNlIjoic2l
nbiIsIngiOiJ4UF83dEkxYWNNRHdFVnhVcC1YdENWeE5Ua3pmUEtVWFlILTF3OFlzZm5V
IiwieSI6IlBrQ1YxSG1ycnVDUmpNNDREQWJkYl8xb3B2MDN4QUVNWmVLYmloX0NFSlEif
SwiaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsInR5cCI6IkpQVCJ9.MTcxNDUyM
TYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~ImpheWRvZUBleGFtcGxlLm9yZyI~eyJj
b3VudHJ5IjoiVVNBIiwiZm9ybWF0dGVkIjoiMTIzNCBNYWluIFN0LlxuQW55dG93biwgQ
0EgMTIzNDVcblVTQSIsImxvY2FsaXR5IjoiQW55dG93biIsInBvc3RhbF9jb2RlIjoxMj
M0NSwicmVnaW9uIjoiQ0EiLCJzdHJlZXRfYWRkcmVzcyI6IjEyMzQgTWFpbiBTdC4ifQ~
dHJ1ZQ.3JleU8_ZBjqlcsWNfq7yUFnqH3-J529Y7JPOTO-VuNQT-YgYwm9oifqsJQiibv
rXLhaUoTKkpGovV6vxd5ByHA~btenJSeYxfYFWF_1WYcQSj5VCY-ecbfibB9Y1V9gHZo
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 Header:
{
"alg": "MAC-H256",
"aud": "https://recipient.example.com",
"nonce": "Kbyx9Mlh-XUgbOdam1vR-dl4WK13Ltn6y7nfvFUQKKM"
}
Figure 24: Presentation 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:
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[
"3JleU8_ZBjqlcsWNfq7yUFnqH3-J529Y7JPOTO-VuNQT-YgYwm9oifqsJQiibvrXLh
aUoTKkpGovV6vxd5ByHA",
"dAl1DDShaQd8JNWxtb_geTjPpdlUvhAYxhjZXQT9m78",
"ixhgL6Xok1TY8qhJQs5RpUUdwaI2UUth-c1kE_Tp9Is",
"AlsVYc-OkHzb-jjK11lXIebmaMydqDqInqVe29W2Vpo",
"sMtqZYvHga5XmI0iXfjt590DUGTkijkW2uBlcxUtNic",
"LCwZOoqRRM0OePErrPelGxf0TEngY8ZjoDDi2OJLHZo",
"BJ5DQg-cWglSDDxdmXs1AD0Zkb09a32h3vCEqFdj0PI",
"d4PaY2wWPAy8xYbK4yYrnZIZAbPKIb0OYScKVd7Er5I",
"eqZSSchOFv_Y9t8kUQd8E5i78RdFE9mI7XMp9MMJvCl7AP6s4vnBKCQUyq3jK2Ly_d
G6QEVubg70oqtkgxXnqQ"
]
Figure 25: Presentation proof (Base64url-Encoded)
The final presented JWP in compact serialization is:
eyJhbGciOiJNQUMtSDI1NiIsImF1ZCI6Imh0dHBzOi8vcmVjaXBpZW50LmV4YW1wbGUuY
29tIiwibm9uY2UiOiJLYnl4OU1saC1YVWdiT2RhbTF2Ui1kbDRXSzEzTHRuNnk3bmZ2Rl
VRS0tNIn0.eyJhbGciOiJNQUMtSDI1NiIsImNsYWltcyI6WyJpYXQiLCJleHAiLCJmYW1
pbHlfbmFtZSIsImdpdmVuX25hbWUiLCJlbWFpbCIsImFkZHJlc3MiLCJhZ2Vfb3Zlcl8y
MSJdLCJocGEiOiJFUzI1NiIsImhwayI6eyJjcnYiOiJQLTI1NiIsImt0eSI6IkVDIiwid
XNlIjoic2lnbiIsIngiOiJ4UF83dEkxYWNNRHdFVnhVcC1YdENWeE5Ua3pmUEtVWFlILT
F3OFlzZm5VIiwieSI6IlBrQ1YxSG1ycnVDUmpNNDREQWJkYl8xb3B2MDN4QUVNWmVLYml
oX0NFSlEifSwiaXNzIjoiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZSIsInR5cCI6IkpQVCJ9
.MTcxNDUyMTYwMA~MTcxNzE5OTk5OQ~IkRvZSI~IkpheSI~~~.3JleU8_ZBjqlcsWNfq7
yUFnqH3-J529Y7JPOTO-VuNQT-YgYwm9oifqsJQiibvrXLhaUoTKkpGovV6vxd5ByHA~d
Al1DDShaQd8JNWxtb_geTjPpdlUvhAYxhjZXQT9m78~ixhgL6Xok1TY8qhJQs5RpUUdwa
I2UUth-c1kE_Tp9Is~AlsVYc-OkHzb-jjK11lXIebmaMydqDqInqVe29W2Vpo~sMtqZYv
Hga5XmI0iXfjt590DUGTkijkW2uBlcxUtNic~LCwZOoqRRM0OePErrPelGxf0TEngY8Zj
oDDi2OJLHZo~BJ5DQg-cWglSDDxdmXs1AD0Zkb09a32h3vCEqFdj0PI~d4PaY2wWPAy8x
YbK4yYrnZIZAbPKIb0OYScKVd7Er5I~eqZSSchOFv_Y9t8kUQd8E5i78RdFE9mI7XMp9M
MJvCl7AP6s4vnBKCQUyq3jK2Ly_dG6QEVubg70oqtkgxXnqQ
Figure 26: Presented JWP (MAC-H256, JSON, Compact Serialization)
Appendix B. Acknowledgements
This work was incubated in the DIF Applied Cryptography Working Group
(https://identity.foundation/working-groups/crypto.html).
We would like to thank Alberto Solavagione for his valuable
contributions to this specification.
The BBS examples were generated using the library at
https://github.com/mattrglobal/pairing_crypto
(https://github.com/mattrglobal/pairing_crypto) .
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Appendix C. Document History
[[ To be removed from the final specification ]]
-14
* MAC-H256 example now includes the correct secret in the issuer
proof
* MAC-H256 example no longer omits some components in signed inputs.
* Align SU-ES256 prose and fixtures for compact and CPT example
payloads and disclosures
* Clarified alg Header Parameter terminology.
* Applied editorial corrections.
* Normalized references and section citations.
* Clarified BBS presentation serialization and example prose.
-13
* Examples are now built deterministically (using RFC 6979
deterministic ECDSA and seeded random number generation for BBS)
* Add proof_alg to JWK and CWK to prevent potential collisions
between the JWS/JWE algorithm registry, COSE algorithms registry,
and JWP algorithms registry
-12
* IANA Considerations section changes from IANA Early Review
* Updated BLS keys to match BLS Key Representations draft 8
-11
* Change Issuer Protected Header to Issuer Header
* Change Presentation Protected Header and Holder Presentation
Header to Presentation Header
-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 independent 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.
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* Do not unnecessarily 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.
* Provide step-by-step instructions for verification of a
presentation
* Change Proof Key to Issuer Ephemeral Key and Presentation Key to
Holder Presentation Key
-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 algorithm usage 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.
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* 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
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-00
* Created initial working group draft based on draft-jmiller-jose-
json-proof-algorithms-01
Authors' Addresses
Michael B. Jones
Self-Issued Consulting
Email: michael_b_jones@hotmail.com
URI: https://self-issued.info/
David Waite
Ping Identity
Email: dwaite+jwp@pingidentity.com
Jeremie Miller
Ping Identity
Email: jmiller@pingidentity.com
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