W3C Candidate Recommendation Draft
Copyright © 2024 World Wide Web Consortium. W3C® liability, trademark and permissive document license rules apply.
This specification describes a Data Integrity cryptographic suite for use when creating or verifying a digital signature using the twisted Edwards Curve Digital Signature Algorithm (EdDSA) and Curve25519 (ed25519).
This section describes the status of this document at the time of its publication. A list of current W3C publications and the latest revision of this technical report can be found in the W3C technical reports index at https://www.w3.org/TR/.
The Working Group is actively seeking implementation feedback for this specification. In order to exit the Candidate Recommendation phase, the Working Group has set the requirement of at least two independent implementations for each mandatory feature in the specification. For details on the conformance testing process, see the test suites listed in the implementation report.
This document was published by the Verifiable Credentials Working Group as a Candidate Recommendation Draft using the Recommendation track.
Publication as a Candidate Recommendation does not imply endorsement by W3C and its Members. A Candidate Recommendation Draft integrates changes from the previous Candidate Recommendation that the Working Group intends to include in a subsequent Candidate Recommendation Snapshot.
This is a draft document and may be updated, replaced or obsoleted by other documents at any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the W3C Patent Policy. W3C maintains a public list of any patent disclosures made in connection with the deliverables of the group; that page also includes instructions for disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains Essential Claim(s) must disclose the information in accordance with section 6 of the W3C Patent Policy.
This document is governed by the 03 November 2023 W3C Process Document.
This specification defines a cryptographic suite for the purpose of creating, verifying proofs for Ed25519 EdDSA signatures in conformance with the Data Integrity [VC-DATA-INTEGRITY] specification. The approach is accepted by the U.S. National Institute of Standards in the latest FIPS 186-5 publication and meets U.S. Federal Information Processing requirements when using cryptography to secure digital information.
The suites described in this specification use the RDF Dataset Canonicalization Algorithm [RDF-CANON] or the JSON Canonicalization Scheme [RFC8785] to transform an input document into its canonical form. The canonical representation is then hashed and signed with a detached signature algorithm.
Terminology used throughout this document is defined in the Terminology section of the Verifiable Credential Data Integrity 1.0 specification.
As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.
The key words MAY, MUST, MUST NOT, and SHOULD 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.
A conforming proof is any concrete expression of the data model that complies with the normative statements in this specification. Specifically, all relevant normative statements in Sections 2. Data Model and 3. Algorithms of this document MUST be enforced.
A conforming processor is any algorithm realized as software and/or hardware that generates or consumes a conforming proof. Conforming processors MUST produce errors when non-conforming documents are consumed.
This document contains examples of JSON and JSON-LD data. Some of these examples
are invalid JSON, as they include features such as inline comments (//
)
explaining certain portions and ellipses (...
) indicating the omission of
information that is irrelevant to the example. These parts would have to be
removed in order to treat the examples as valid JSON or JSON-LD.
The following sections outline the data model that is used by this specification to express verification methods, such as cryptographic public keys, and data integrity proofs, such as digital signatures.
This cryptographic suite is used to verify Data Integrity Proofs [VC-DATA-INTEGRITY] produced using Edwards Curve cryptographic key material. The encoding formats for those key types are provided in this section. Lossless cryptographic key transformation processes that result in equivalent cryptographic key material MAY be used for the processing of digital signatures.
The Multikey format, defined in [VC-DATA-INTEGRITY], is used to express public keys for the cryptographic suites defined in this specification.
The publicKeyMultibase
value of the verification method MUST start with the
base-58-btc prefix (z
), as defined in the
Multibase section of
[VC-DATA-INTEGRITY]. A Multibase-encoded Multikey value follows, which MUST
consist of a binary value that starts with the two-byte prefix 0xed01
, which
is the Multikey header for an Ed25519 public key, followed by the 32-byte public
key data, all of which is then encoded using base-58-btc. Any other encoding
MUST NOT be allowed.
Developers are advised to not accidentally publish a representation of a private
key. Implementations of this specification will raise errors if they encounter a
Multikey prefix value other than 0xed01
in a publicKeyMultibase
value.
{ "id": "https://example.com/issuer/123#key-0", "type": "Multikey", "controller": "https://example.com/issuer/123", "publicKeyMultibase": "z6Mkf5rGMoatrSj1f4CyvuHBeXJELe9RPdzo2PKGNCKVtZxP" }
{ "@context": [ "https://www.w3.org/ns/did/v1", "https://w3id.org/security/multikey/v1" ], "id": "did:example:123", "verificationMethod": [{ "id": "did:example:123#key-0", "type": "Multikey", "controller": "did:example:123", "publicKeyMultibase": "z6Mkf5rGMoatrSj1f4CyvuHBeXJELe9RPdzo2PKGNCKVtZxP" }], "authentication": [ "did:example:123#key-0" ], "assertionMethod": [ "did:example:123#key-0" ], "capabilityDelegation": [ "did:example:123#key-0" ], "capabilityInvocation": [ "did:example:123#key-0" ] }
The secretKeyMultibase
property represents a Multibase-encoded Multikey
expression of an Ed25519 secret key (sometimes also referred to as a private
key). The value starts with the two-byte prefix 0x8026
,
followed by the 32-byte Ed25519 secret key data. The combined
34-byte value is then base58-btc encoded and z
is added as the prefix on the
encoded value.
Developers are advised to prevent accidental publication of a representation of
a secret key, and to not export the secretKeyMultibase
property by default,
when serializing key pairs to Multikey.
This section details the proof representation formats that are defined by this specification.
A proof contains the attributes specified in the Proofs section of [VC-DATA-INTEGRITY] with the following restrictions.
The type
property MUST be DataIntegrityProof
.
The cryptosuite
property of the proof MUST be eddsa-rdfc-2022
or eddsa-jcs-2022
.
The proofValue
property of the proof MUST be a detached EdDSA
produced according to [RFC8032], encoded using the base-58-btc header and
alphabet as described in the
Multibase section of
[VC-DATA-INTEGRITY].
{ "@context": [ {"myWebsite": "https://vocabulary.example/myWebsite"}, "https://www.w3.org/ns/credentials/v2" ], "myWebsite": "https://hello.world.example/", "proof": { "type": "DataIntegrityProof", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1 cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", "proofPurpose": "assertionMethod", "proofValue": "z5C5b1uzYJN6pDR3aWgAqUMoSB1JY29epA74qyjaie9qh4okm9DZP6y77eTNq 5NfYyMwNu9bpQQWUHKH5zAmEtszK" } }
The following section describes multiple Data Integrity cryptographic suites that utilize the twisted Edwards Curve Digital Signature Algorithm.
This algorithm is used to configure a cryptographic suite to be used by the Add Proof and Verify Proof functions in Verifiable Credential Data Integrity 1.0. The algorithm takes an options object (map options) as input and returns a cryptosuite instance (struct cryptosuite).
DataIntegrityProof
, return cryptosuite.
eddsa-rdfc-2022
:
eddsa-jcs-2022
:
The eddsa-rdfc-2022
cryptographic suite takes an input document, canonicalizes
the document using the RDF Dataset Canonicalization algorithm [RDF-CANON], and then
cryptographically hashes and signs the output
resulting in the production of a data integrity proof. The algorithms in this
section also include the verification of such a data integrity proof.
When the RDF Dataset Canonicalization Algorithm [RDF-CANON] is used, implementations will detect dataset poisoning by default, and abort processing upon such detection.
The following algorithm specifies how to create a data integrity proof given an unsecured data document. Required inputs are an unsecured data document (map unsecuredDocument), and a set of proof options (map options). A data integrity proof (map), or an error, is produced as output.
The following algorithm specifies how to verify a data integrity proof given an secured data document. Required inputs are an secured data document (map securedDocument). This algorithm returns a verification result, which is a struct whose items are:
true
or false
false
, Null;
otherwise, an unsecured data document
proof
value removed.
proofValue
removed.
true
, unsecuredDocument;
otherwise, NullThe following algorithm specifies how to transform an unsecured input document into a transformed document that is ready to be provided as input to the hashing algorithm in Section 3.2.4 Hashing (eddsa-rdfc-2022).
Required inputs to this algorithm are an unsecured data document (unsecuredDocument) and transformation options (options). The transformation options MUST contain a type identifier for the cryptographic suite (type) and a cryptosuite identifier (cryptosuite). A transformed data document is produced as output. Whenever this algorithm encodes strings, it MUST use UTF-8 encoding.
DataIntegrityProof
and options.cryptosuite is not
set to the string eddsa-rdfc-2022
,
an error MUST be raised that SHOULD convey an error type of
PROOF_TRANSFORMATION_ERROR.
The following algorithm specifies how to cryptographically hash a transformed data document and proof configuration into cryptographic hash data that is ready to be provided as input to the algorithms in Section 3.2.6 Proof Serialization (eddsa-rdfc-2022) or Section 3.2.7 Proof Verification (eddsa-rdfc-2022).
The required inputs to this algorithm are a transformed data document (transformedDocument) and canonical proof configuration (canonicalProofConfig). A single hash data value represented as series of bytes is produced as output.
The following algorithm specifies how to generate a proof configuration from a set of proof options that is used as input to the proof hashing algorithm.
The required inputs to this algorithm are the document (unsecuredDocument) and the proof options (options). The proof options MUST contain a type identifier for the cryptographic suite (type) and MUST contain a cryptosuite identifier (cryptosuite). A proof configuration object is produced as output.
DataIntegrityProof
and/or
proofConfig.cryptosuite is not set to eddsa-rdfc-2022
, an
error MUST be raised and SHOULD convey an error type of
PROOF_GENERATION_ERROR.
The following algorithm specifies how to serialize a digital signature from a set of cryptographic hash data. This algorithm is designed to be used in conjunction with the algorithms defined in the Data Integrity [VC-DATA-INTEGRITY] specification, Section 4: Algorithms. Required inputs are cryptographic hash data (hashData) and proof options (options). The proof options MUST contain a type identifier for the cryptographic suite (type) and MAY contain a cryptosuite identifier (cryptosuite). A single digital proof value represented as series of bytes is produced as output.
Ed25519
variant
(Pure EdDSA), with hashData as the data to be signed using
the private key specified by privateKeyBytes.
proofBytes will be exactly 64 bytes in size.
The following algorithm specifies how to verify a digital signature from a set of cryptographic hash data. This algorithm is designed to be used in conjunction with the algorithms defined in the Data Integrity [VC-DATA-INTEGRITY] specification, Section 4: Algorithms. Required inputs are cryptographic hash data (hashData), a digital signature (proofBytes) and proof options (options). A verification result represented as a boolean value is produced as output.
Ed25519
variant (Pure EdDSA),
with hashData as the data to be verified against the
proofBytes using the public key specified by
publicKeyBytes.
The eddsa-jcs-2022
cryptographic suite takes an input document, canonicalizes
the document using the JSON Canonicalization Scheme [RFC8785], and then
cryptographically hashes and signs the output resulting in the production of a
data integrity proof.
The following algorithm specifies how to create a data integrity proof given an unsecured data document. Required inputs are an unsecured data document (map unsecuredDocument), and a set of proof options (map options). A data integrity proof (map), or an error, is produced as output.
The following algorithm specifies how to verify a data integrity proof given an secured data document. Required inputs are an secured data document (map securedDocument). This algorithm returns a verification result, which is a struct whose items are:
true
or false
true
, an unsecured data document;
otherwise Null
proof
value
removed.
proofValue
removed.
false
and skip to the last step.
true
, unsecuredDocument;
otherwise, NullThe following algorithm specifies how to transform an unsecured input document into a transformed document that is ready to be provided as input to the hashing algorithm in Section 3.3.4 Hashing (eddsa-jcs-2022).
Required inputs to this algorithm are an unsecured data document (unsecuredDocument) and transformation options (options). The transformation options MUST contain a type identifier for the cryptographic suite (type) and a cryptosuite identifier (cryptosuite). A transformed data document is produced as output. Whenever this algorithm encodes strings, it MUST use UTF-8 encoding.
DataIntegrityProof
and options.cryptosuite is not
set to the string eddsa-jcs-2022
,
an error MUST be raised that SHOULD convey an error type of
PROOF_VERIFICATION_ERROR.
The following algorithm specifies how to cryptographically hash a transformed data document and proof configuration into cryptographic hash data that is ready to be provided as input to the algorithms in Section 3.3.6 Proof Serialization (eddsa-jcs-2022) or Section 3.3.7 Proof Verification (eddsa-jcs-2022).
The required inputs to this algorithm are a transformed data document (transformedDocument) and canonical proof configuration (canonicalProofConfig). A single hash data value represented as series of bytes is produced as output.
The following algorithm specifies how to generate a proof configuration from a set of proof options that is used as input to the proof hashing algorithm.
The required inputs to this algorithm are proof options (options). The proof options MUST contain a type identifier for the cryptographic suite (type) and MUST contain a cryptosuite identifier (cryptosuite). A proof configuration object is produced as output.
DataIntegrityProof
or
proofConfig.cryptosuite is not set to eddsa-jcs-2022
,
an error MUST be raised that SHOULD convey an error type of
PROOF_GENERATION_ERROR.
The following algorithm specifies how to serialize a digital signature from a set of cryptographic hash data. This algorithm is designed to be used in conjunction with the algorithms defined in the Data Integrity [VC-DATA-INTEGRITY] specification, Section 4: Algorithms. Required inputs are cryptographic hash data (hashData) and proof options (options). The proof options MUST contain a type identifier for the cryptographic suite (type) and MAY contain a cryptosuite identifier (cryptosuite). A single digital proof value represented as series of bytes is produced as output.
Ed25519
variant
(Pure EdDSA), with hashData as the data to be signed using
the private key specified by privateKeyBytes.
proofBytes will be exactly 64 bytes in size.
The following algorithm specifies how to verify a digital signature from a set of cryptographic hash data. This algorithm is designed to be used in conjunction with the algorithms defined in the Data Integrity [VC-DATA-INTEGRITY] specification, Section 4: Algorithms. Required inputs are cryptographic hash data (hashData), a digital signature (proofBytes) and proof options (options). A verification result represented as a boolean value is produced as output.
Ed25519
variant (Pure EdDSA),
with hashData as the data to be verified against the
proofBytes using the public key specified by
publicKeyBytes.
Before reading this section, readers are urged to familiarize themselves with general security advice provided in the Security Considerations section of the Data Integrity specification.
The following section describes security considerations that developers implementing this specification should be aware of in order to create secure software.
This section is non-normative.
Ed25519 signatures (EdDSA algorithm with edwards25519 curve) have been widely adopted, due both to the compact size of the keys and signatures and to the speed at which signatures can be produced and verified. Many libraries exist that can create and verify Ed25519 signatures. Since the publication of [RFC8032], security properties of Ed25519 signatures have been rigorously proven (see [Provable_Ed25519] and [Taming_EdDSAs]). However, it has been observed that a significant number of libraries do not achieve these security levels, due to missing input validity checks during the signature verification process. In this section, we summarize the security levels achievable with Ed25519 signatures, and indicate how one can determine whether a library will support those levels.
Digital signatures might exhibit a number of desirable cryptographic properties [Taming_EdDSAs] among these are:
EUF-CMA (existential unforgeability under chosen message attacks) is usually the minimal security property required of a signature scheme. It guarantees that any efficient adversary who has the public key of the signer and received an arbitrary number of signatures on messages of its choice (in an adaptive manner): , cannot output a valid signature for a new message (except with negligible probability). If the attacker outputs a valid signature on a new message: , it is called an existential forgery.
SUF-CMA (strong unforgeability under chosen message attacks) is a stronger notion than EUF-CMA. It guarantees that for any efficient adversary who has the public key of the signer and received an arbitrary number of signatures on messages of its choice: , it cannot output a new valid signature pair , such that (except with negligible probability). Strong unforgeability implies that an adversary not only cannot sign new messages, but also cannot find a new signature on an old message. See [Provable_Ed25519] for a real world attack that would have been circumvented with SUF-CMA security over EUF-CMA security.
Binding signature (BS) We say that a signature scheme is binding if no efficient signer can output a tuple , where both and are valid message signature pairs under the public key and (except with negligible probability). A binding signature makes it impossible for the signer to claim later that it has signed a different message; the signature binds the signer to the message.
Strongly Binding signature (SBS) Certain applications may require a signature to not only be binding to the message but also be binding to the public key. We say that a signature scheme is strongly-binding if any efficient signer cannot output a tuple , where is a valid signature for the public key and is a valid signature for the public key and either or , or both (except with negligible probability). See [Provable_Ed25519] for real world attacks that would have been circumvented with the SBS property.
Note that the BS and SBS properties are forms of non-repudiation.
As pointed out in [Taming_EdDSAs], flaws in Ed25519 libraries primarily occur on the signature verification side, where edge cases are sometimes not properly checked. An Ed25519 signature library that is in conformance with [RFC8032] or [FIPS-186-5], i.e., one that performs all specified validation checks, will have the SUF-CMA property in addition to EUF-CMA.
Reference [Taming_EdDSAs] achieves the BS and SBS properties along with SUF-CMA in their "signature verification algorithm 2" where an additional check is performed against the public key A to make sure that it is not one of eight "small order points". These additional checks incur minimal processing overhead.
Reference [Taming_EdDSAs] included a set of twelve test vectors to test various Ed25519 libraries available at the time of publication. They found that a significant portion missed edge cases and hence did not achieve SUF-CMA (just EUF-CMA), and only two libraries out of sixteen achieved all the security properties. Since the time of publication, more Ed25519 libraries have been created, and some of the libraries have been updated to include all verification checks. Implementers are recommended to test the Ed25519 library they are using against the test vectors of [Taming_EdDSAs].
Before reading this section, readers are urged to familiarize themselves with general privacy advice provided in the Privacy Considerations section of the Data Integrity specification.
The following section describes privacy considerations that developers implementing this specification should be aware of in order to avoid violating privacy assumptions.
This cryptography suite does not provide for selective disclosure or unlinkability. If signatures are re-used, they can be used as correlatable data.
Ed25519Signature2020
is an earlier version of a cryptographic suite
for use of the EdDSA algorithm and Curve25519. While it has
been used in production systems, new implementations should instead use
eddsa-rdfc-2022
. Ed25519Signature2020
has
been kept in this specification to provide a stable reference.
We need to add documentation to note that this key format is deployed and
widely used in production, but is deprecated. Multikey
and JsonWebKey
supersede it.
The type
of the verification method MUST be
Ed25519VerificationKey2020.
The controller
of the verification method MUST be a URL.
The publicKeyMultibase
value of the verification method MUST start with the
base-58-btc prefix (z
), as defined in the
Multibase section of
[VC-DATA-INTEGRITY]. A Multibase-encoded Multikey value follows, which MUST
consist of a binary value that starts with the two-byte prefix 0xed01
, which
is the Multikey header for an Ed25519 public key, followed by the 32-byte
public key data, all of which is then encoded using base-58-btc. Any other
encoding MUST NOT be allowed.
Developers are advised to not accidentally publish a representation of a private
key. Implementations of this specification will raise errors in the event of a
Multikey header value other than 0xed01
being used in a
publicKeyMultibase
value.
{ "id": "https://example.com/issuer/123#key-0", "type": "Ed25519VerificationKey2020", "controller": "https://example.com/issuer/123", "publicKeyMultibase": "z6Mkf5rGMoatrSj1f4CyvuHBeXJELe9RPdzo2PKGNCKVtZxP" }
{ "@context": [ "https://www.w3.org/ns/did/v1", "https://w3id.org/security/suites/ed25519-2020/v1" ], "id": "did:example:123", "verificationMethod": [{ "id": "did:example:123#key-0", "type": "Ed25519VerificationKey2020", "controller": "did:example:123", "publicKeyMultibase": "z6Mkf5rGMoatrSj1f4CyvuHBeXJELe9RPdzo2PKGNCKVtZxP" }], "authentication": [ "did:example:123#key-0" ], "assertionMethod": [ "did:example:123#key-0" ], "capabilityDelegation": [ "did:example:123#key-0" ], "capabilityInvocation": [ "did:example:123#key-0" ] }
The verificationMethod
property of the proof MUST be a URL.
Dereferencing the verificationMethod
MUST result in an object
containing a type
property with the value set to
Ed25519VerificationKey2020
.
The type
property of the proof MUST be Ed25519Signature2020
.
The created
property of the proof MUST be an [XMLSCHEMA11-2]
formatted date string.
The proofPurpose
property of the proof MUST be a string, and MUST
match the verification relationship expressed by the verification method
controller
.
The proofValue
property of the proof MUST be a detached EdDSA
produced according to [RFC8032], encoded using
the base-58-btc header and alphabet as described in the
Multibase section of [VC-DATA-INTEGRITY].
{ "@context": [ {"myWebsite": "https://vocabulary.example/myWebsite"}, "https://w3id.org/security/suites/ed25519-2020/v1" ], "myWebsite": "https://hello.world.example/", "proof": { "type": "Ed25519Signature2020", "created": "2020-11-05T19:23:24Z", "verificationMethod": "https://di.example/issuer#z6MkjLrk3gKS2nnkeWcmcxiZPGskmesDpuwRBorgHxUXfxnG", "proofPurpose": "assertionMethod", "proofValue": "z4oey5q2M3XKaxup3tmzN4DRFTLVqpLMweBrSxMY2xHX5XTYVQeVbY8nQAVHMrXFkXJpmEcqdoDwLWxaqA3Q1geV6" } }
The Ed25519Signature2020
cryptographic suite takes an input document,
canonicalizes the document using the RDF Dataset Canonicalization algorithm [RDF-CANON],
and then cryptographically hashes and signs the output
resulting in the production of a data integrity proof. The algorithms in this
section also include the verification of such a data integrity proof.
To generate a proof, the algorithm in Section 4.1: Add Proof in the Data Integrity [VC-DATA-INTEGRITY] specification MUST be executed. For that algorithm, the cryptographic suite specific transformation algorithm is defined in Section A.2.1.3 Transformation (Ed25519Signature2020), the hashing algorithm is defined in Section A.2.1.4 Hashing (Ed25519Signature2020), and the proof serialization algorithm is defined in Section A.2.1.6 Proof Serialization (Ed25519Signature2020).
To verify a proof, the algorithm in Section 4.2: Verify Proof in the Data Integrity [VC-DATA-INTEGRITY] specification MUST be executed. For that algorithm, the cryptographic suite specific transformation algorithm is defined in Section A.2.1.3 Transformation (Ed25519Signature2020), the hashing algorithm is defined in Section A.2.1.4 Hashing (Ed25519Signature2020), and the proof verification algorithm is defined in Section A.2.1.7 Proof Verification (Ed25519Signature2020).
The following algorithm specifies how to transform an unsecured input document into a transformed document that is ready to be provided as input to the hashing algorithm in Section A.2.1.4 Hashing (Ed25519Signature2020).
Required inputs to this algorithm are an unsecured data document (unsecuredDocument) and transformation options (options). The transformation options MUST contain a type identifier for the cryptographic suite (type) and a cryptosuite identifier (cryptosuite). A transformed data document is produced as output. Whenever this algorithm encodes strings, it MUST use UTF-8 encoding.
Ed25519Signature2020
,
an error MUST be raised that SHOULD convey an error type of
PROOF_TRANSFORMATION_ERROR.
The following algorithm specifies how to cryptographically hash a transformed data document and proof configuration into cryptographic hash data that is ready to be provided as input to the algorithms in Section A.2.1.6 Proof Serialization (Ed25519Signature2020) or Section A.2.1.7 Proof Verification (Ed25519Signature2020).
The required inputs to this algorithm are a transformed data document (transformedDocument) and proof configuration (proofConfig). The proof configuration MUST contain a type identifier for the cryptographic suite (type) and MAY contain a cryptosuite identifier (cryptosuite). A single hash data value represented as series of bytes is produced as output.
The following algorithm specifies how to generate a proof configuration from a set of proof options that is used as input to the proof hashing algorithm.
The required inputs to this algorithm are proof options (options). The proof options MUST contain a type identifier for the cryptographic suite (type) and MAY contain a cryptosuite identifier (cryptosuite). A proof configuration object is produced as output.
Ed25519Signature2020
,
an error MUST be raised and SHOULD convey an error type of
PROOF_GENERATION_ERROR.
The following algorithm specifies how to serialize a digital signature from a set of cryptographic hash data. This algorithm is designed to be used in conjunction with the algorithms defined in the Data Integrity [VC-DATA-INTEGRITY] specification, Section 4: Algorithms. Required inputs are cryptographic hash data (hashData) and proof options (options). The proof options MUST contain a type identifier for the cryptographic suite (type) and MAY contain a cryptosuite identifier (cryptosuite). A single digital proof value represented as series of bytes is produced as output.
Ed25519
variant
(Pure EdDSA), with hashData as the data to be signed using
the private key specified by privateKeyBytes.
proofBytes will be exactly 64 bytes in size.
The following algorithm specifies how to verify a digital signature from a set of cryptographic hash data. This algorithm is designed to be used in conjunction with the algorithms defined in the Data Integrity [VC-DATA-INTEGRITY] specification, Section 4: Algorithms. Required inputs are cryptographic hash data (hashData), a digital signature (proofBytes) and proof options (options). A verification result represented as a boolean value is produced as output.
Ed25519
variant (Pure EdDSA),
with hashData as the data to be verified against the
proofBytes using the public key specified by
publicKeyBytes.
This section is non-normative.
The signer needs to generate a private/public key pair with the private key used for signing and the public key made available for verification. The representation of the public key and the representation of the private key are shown below.
{ publicKeyMultibase: "z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", privateKeyMultibase: "z3u2en7t5LR2WtQH5PfFqMqwVHBeXouLzo6haApm8XHqvjxq" }
Signing begins with a credential without an attached proof, which is converted to canonical form, and then hashed, as shown in the following three examples.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": ["VerifiableCredential", "AlumniCredential"], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" } }
<did:example:abcdefgh> <https://www.w3.org/ns/credentials/examples#alumniOf> "The School of Examples" . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <https://www.w3.org/2018/credentials#VerifiableCredential> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <https://www.w3.org/ns/credentials/examples#AlumniCredential> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://schema.org/description> "A minimum viable example of an Alumni Credential." . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://schema.org/name> "Alumni Credential" . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://www.w3.org/2018/credentials#credentialSubject> <did:example:abcdefgh> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://www.w3.org/2018/credentials#issuer> <https://vc.example/issuers/5678> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://www.w3.org/2018/credentials#validFrom> "2023-01-01T00:00:00Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> .
517744132ae165a5349155bef0bb0cf2258fff99dfe1dbd914b938d775a36017
The next step is to take the proof options document, convert it to canonical form, and obtain its hash, as shown in the next three examples.
{ "type": "DataIntegrityProof", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", "proofPurpose": "assertionMethod", "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ] }
_:c14n0 <http://purl.org/dc/terms/created> "2023-02-24T23:36:38Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> . _:c14n0 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <https://w3id.org/security#DataIntegrityProof> . _:c14n0 <https://w3id.org/security#cryptosuite> "eddsa-rdfc-2022"^^<https://w3id.org/security#cryptosuiteString> . _:c14n0 <https://w3id.org/security#proofPurpose> <https://w3id.org/security#assertionMethod> . _:c14n0 <https://w3id.org/security#verificationMethod> <https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2> .
4c4d3890a157f8d611b13c265c2c22f39aa0a567c7c7dd9ba3e45cd579784eeb
Finally, we concatenate the hash of the proof options followed by the hash of the credential without proof, use the private key with the combined hash to compute the Ed25519 signature, and then base58-btc encode the signature.
4c4d3890a157f8d611b13c265c2c22f39aa0a567c7c7dd9ba3e45cd579784eeb517744132ae165a5349155bef0bb0cf2258fff99dfe1dbd914b938d775a36017
3237ba3b695c09e199540507ead17a58300cc4efe91ce19d582ad7e001455190f1ea3d13bdeff2cbaf7f30da7fe9f24b475511ef3875b6efe7cc9f49d3f55b02
z21EVs3eXERqTn4acNHT9viboqgzUaQ3kTmhPT3eA8qrVPE7CrQq78WkzctnMX5W4CrzcKnHw8V6dvy5pgWYCU5e9
Assemble the signed credential with the following two steps:
proofValue
field with the previously computed base58-btc
value to the proof options document.
proof
field of the credential to the augmented proof
option document.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": { "type": "DataIntegrityProof", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", "proofPurpose": "assertionMethod", "proofValue": "z21EVs3eXERqTn4acNHT9viboqgzUaQ3kTmhPT3eA8qrVPE7CrQq78WkzctnMX5W4CrzcKnHw8V6dvy5pgWYCU5e9" } }
The signer needs to generate a private/public key pair with the private key used for signing and the public key made available for verification. The representation of the public key, and the representation of the private key are shown below.
{ publicKeyMultibase: "z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", privateKeyMultibase: "z3u2en7t5LR2WtQH5PfFqMqwVHBeXouLzo6haApm8XHqvjxq" }
Signing begins with a credential without an attached proof, which is converted to canonical form, and then hashed, as shown in the following three examples.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": ["VerifiableCredential", "AlumniCredential"], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" } }
{"@context":["https://www.w3.org/ns/credentials/v2","https://www.w3.org/ns/credentials/examples/v2"],"credentialSubject":{"alumniOf":"The School of Examples","id":"did:example:abcdefgh"},"description":"A minimum viable example of an Alumni Credential.","id":"urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33","issuer":"https://vc.example/issuers/5678","name":"Alumni Credential","type":["VerifiableCredential","AlumniCredential"],"validFrom":"2023-01-01T00:00:00Z"}
59b7cb6251b8991add1ce0bc83107e3db9dbbab5bd2c28f687db1a03abc92f19
The next step is to take the proof options document, convert it to canonical form, and obtain its hash, as shown in the next three examples.
{ "type": "DataIntegrityProof", "cryptosuite": "eddsa-jcs-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", "proofPurpose": "assertionMethod", "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ] }
{"@context":["https://www.w3.org/ns/credentials/v2","https://www.w3.org/ns/credentials/examples/v2"],"created":"2023-02-24T23:36:38Z","cryptosuite":"eddsa-jcs-2022","proofPurpose":"assertionMethod","type":"DataIntegrityProof","verificationMethod":"https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2"}
ac75a9fbdb9b5606c064a88bb59ab355900074f6def99d16a82dd071a7a67066
Finally, we concatenate the hash of the proof options followed by the hash of the credential without proof, use the private key with the combined hash to compute the Ed25519 signature, and then base58-btc encode the signature.
ac75a9fbdb9b5606c064a88bb59ab355900074f6def99d16a82dd071a7a6706659b7cb6251b8991add1ce0bc83107e3db9dbbab5bd2c28f687db1a03abc92f19
fc91dec6565f35fbe185a77352e7fc512f95d1904da305cfef32ab8135469301f5a72d4e7a58368fc6ffc497b44633993bac054e3bc1436e3c846db8f1544503
z63t83Y53KfzJ5ZosfKTnqfMcKB2dmTrfjSaQjeNNjAD5srBowQfmWqeRb8rRjmeEuCBEsddF9LsVogtuTsijJKh4
Assemble the signed credential with the following two steps:
proofValue
field with the previously computed base58-btc
value to the proof options document.
proof
field of the credential to the augmented proof
option document.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": { "type": "DataIntegrityProof", "cryptosuite": "eddsa-jcs-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", "proofPurpose": "assertionMethod", "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "proofValue": "z63t83Y53KfzJ5ZosfKTnqfMcKB2dmTrfjSaQjeNNjAD5srBowQfmWqeRb8rRjmeEuCBEsddF9LsVogtuTsijJKh4" } }
The signer needs to generate a private/public key pair with the private key used for signing and the public key made available for verification. The representation of the public key, and the representation of the private key, are shown below.
{ publicKeyMultibase: "z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", privateKeyMultibase: "z3u2en7t5LR2WtQH5PfFqMqwVHBeXouLzo6haApm8XHqvjxq" }
Signing begins with a credential without an attached proof, which is converted to canonical form, and then hashed, as shown in the following three examples.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": ["VerifiableCredential", "AlumniCredential"], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" } }
<did:example:abcdefgh> <https://www.w3.org/ns/credentials/examples#alumniOf> "The School of Examples" . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <https://www.w3.org/2018/credentials#VerifiableCredential> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <https://www.w3.org/ns/credentials/examples#AlumniCredential> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://schema.org/description> "A minimum viable example of an Alumni Credential." . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://schema.org/name> "Alumni Credential" . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://www.w3.org/2018/credentials#credentialSubject> <did:example:abcdefgh> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://www.w3.org/2018/credentials#issuer> <https://vc.example/issuers/5678> . <urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33> <https://www.w3.org/2018/credentials#validFrom> "2023-01-01T00:00:00Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> .
517744132ae165a5349155bef0bb0cf2258fff99dfe1dbd914b938d775a36017
The next step is to take the proof options document, convert it to canonical form, and obtain its hash, as shown in the next three examples.
{ "type": "Ed25519Signature2020", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", "proofPurpose": "assertionMethod", "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2", "https://w3id.org/security/suites/ed25519-2020/v1" ] }
_:c14n0 <http://purl.org/dc/terms/created> "2023-02-24T23:36:38Z"^^<http://www.w3.org/2001/XMLSchema#dateTime> . _:c14n0 <http://www.w3.org/1999/02/22-rdf-syntax-ns#type> <https://w3id.org/security#Ed25519Signature2020> . _:c14n0 <https://w3id.org/security#proofPurpose> <https://w3id.org/security#assertionMethod> . _:c14n0 <https://w3id.org/security#verificationMethod> <https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2> .
5e41905a6915396ff4eb426ce26c322d0e1d870b3d75cef95612cc94e4f8bad7
Finally, we concatenate the hash of the proof options followed by the hash of the credential without proof, use the private key with the combined hash to compute the Ed25519 signature, and then base58-btc encode the signature.
5e41905a6915396ff4eb426ce26c322d0e1d870b3d75cef95612cc94e4f8bad7517744132ae165a5349155bef0bb0cf2258fff99dfe1dbd914b938d775a36017
d6310be6e26c28c327abc6f9e392c9f91c4e5f71252a8a3bc6acfedcc62a1c216e8979afdbb1badaa57e4ed8ad362af447ac6e649a074d5ea99788e3343b980b
z5HNuvc5WbWYsRRt97kXJ6SoKgb1tMwtkQND4pnobZE26JGnohdWVpzashF9d8FRzhzm8oYRSivKACTakeE4DzdHL
Assemble the signed credential with the following two steps:
proofValue
field with the previously computed base58-btc
value to the proof options document.
proof
field of the credential to the augmented proof
option document.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2", "https://w3id.org/security/suites/ed25519-2020/v1" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": { "type": "Ed25519Signature2020", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/5678#z6MkrJVnaZkeFzdQyMZu1cgjg7k1pZZ6pvBQ7XJPt4swbTQ2", "proofPurpose": "assertionMethod", "proofValue": "z5HNuvc5WbWYsRRt97kXJ6SoKgb1tMwtkQND4pnobZE26JGnohdWVpzashF9d8FRzhzm8oYRSivKACTakeE4DzdHL" } }
Proof sets and chains are defined in the [VC-DATA-INTEGRITY]. We
provide test vectors showing the creation of proof sets and chains with the
eddsa-rdfc-2022
cryptosuite. Multiple signers can be involved in the generation
of proof sets and chains so multiple public/private key pairs are needed. These
are shown below.
{ "keyPair1": { "publicKeyMultibase": "z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "privateKeyMultibase": "z3u2W4YnTstS1nSSBAgZcYSJF43JuZ9uLV6bF38B1Bf8NugW" }, "keyPair2": { "publicKeyMultibase": "z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "privateKeyMultibase": "z3u2cfp4Q17kMGhNCh348a3yw3cUBiWK6RXRzyJE54sixMFn" }, "keyPair3": { "publicKeyMultibase": "z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "privateKeyMultibase": "z3u2Zr3tcDLBDQKGxVa9SRDFNLqNqPWsa8p9rWPvCEH6bADB" }, "keyPair4": { "publicKeyMultibase": "z6Mkm1S51iPHJvDEkJ9MRtxJmT8Pqo6wHipAFwBAjN83vntT", "privateKeyMultibase": "z3u2ZTWiFwM17veUR7sXniY66Gf14SqMdpMLy7SW9x4EDdmw" } }
The original unsigned credential is shown below:
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": ["VerifiableCredential", "AlumniCredential"], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" } }
To demonstrate creating a proof set, we start with a document containing a
single proof and add another proof to it. The starting document is shown below and
contains a proof signed with keyPair1
.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": { "type": "DataIntegrityProof", "id": "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56781#z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "proofPurpose": "assertionMethod", "proofValue": "z5KTX5yikM4eUukZW9qh66LGT3KZEUCACGpWcT2t4Yd54NMoFRchGmH4778omyNFAD3weSt6sNk5fuaMQmhhzNmEC" } }
The options
input to
Section 4.4: Add Proof Set/Chain in [VC-DATA-INTEGRITY]
is shown below. Note that it does not include a previousProof
attribute since
we are constructing a proof set and not a chain. In addition, we will be using
keyPair2
for signing.
{ "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod" }
Per the algorithm of
Section 4.4: Add Proof Set/Chain in [VC-DATA-INTEGRITY],
we create an array variable, allProofs, and add the proof from the
starting document to it. Since there is no previousProof
attribute, no
modification of unsignedDocument
is needed prior to computing the signed proof
in step 6 of
Section 4.4: Add Proof Set/Chain in
[VC-DATA-INTEGRITY]. The signed proof configuration is shown below.
{ "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod", "proofValue": "z5KXNyXDcm822dHS37tmS6Xc7FFNo8c73AfeqmfHoywPxnXWNjWKYK3VQzt3CMUoK9uAqsboVHKJXxuYwbdnfxZeA" }
The signed proof options
above gets appended to the allProofs
variable, which then gets set as the proof
attribute of the unsigned document
to produce the final signed document as shown below.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": [ { "type": "DataIntegrityProof", "id": "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56781#z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "proofPurpose": "assertionMethod", "proofValue": "z5KTX5yikM4eUukZW9qh66LGT3KZEUCACGpWcT2t4Yd54NMoFRchGmH4778omyNFAD3weSt6sNk5fuaMQmhhzNmEC" }, { "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod", "proofValue": "z5KXNyXDcm822dHS37tmS6Xc7FFNo8c73AfeqmfHoywPxnXWNjWKYK3VQzt3CMUoK9uAqsboVHKJXxuYwbdnfxZeA" } ] }
This collection of test vectors demonstrates the construction a proof chain. We
start with a document containing a proof set, i.e., our previous example, and
then add a new proof to the credential that has a dependency on the existing
proofs. This example also demonstrates the case where the previousProofs
attribute is an array. This example uses keyPair3
and the starting document is
given below.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": [ { "type": "DataIntegrityProof", "id": "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56781#z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "proofPurpose": "assertionMethod", "proofValue": "z5KTX5yikM4eUukZW9qh66LGT3KZEUCACGpWcT2t4Yd54NMoFRchGmH4778omyNFAD3weSt6sNk5fuaMQmhhzNmEC" }, { "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod", "proofValue": "z5KXNyXDcm822dHS37tmS6Xc7FFNo8c73AfeqmfHoywPxnXWNjWKYK3VQzt3CMUoK9uAqsboVHKJXxuYwbdnfxZeA" } ] }
The options
input to
Section 4.4: Add Proof Set/Chain in [VC-DATA-INTEGRITY]
is shown below. Note that it includes a previousProof
attribute since we are
constructing a proof chain.
{ "type": "DataIntegrityProof", "id": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:06:38Z", "verificationMethod": "https://vc.example/issuers/56783#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": [ "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54" ] }
Per the algorithm of
Section 4.4: Add Proof Set/Chain in [VC-DATA-INTEGRITY],
we create an array variable, allProofs, and add the proofs from the
starting document to it. Since the options contains the previousProof
attribute, we compute the matchingProofs variable per step 4
of Section 4.4: Add Proof
Set/Chain, and we set the
unsecuredDocument.proof equal to the matchingProofs. This
produces the document shown below.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": [ { "type": "DataIntegrityProof", "id": "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56781#z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "proofPurpose": "assertionMethod", "proofValue": "z5KTX5yikM4eUukZW9qh66LGT3KZEUCACGpWcT2t4Yd54NMoFRchGmH4778omyNFAD3weSt6sNk5fuaMQmhhzNmEC" }, { "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod", "proofValue": "z5KXNyXDcm822dHS37tmS6Xc7FFNo8c73AfeqmfHoywPxnXWNjWKYK3VQzt3CMUoK9uAqsboVHKJXxuYwbdnfxZeA" } ] }
In step 6, we use the previous document (unsecured document with previous proofs
added to it) to compute the proofValue
attribute. This gives the signed
configuration options (proof) shown below:
{ "type": "DataIntegrityProof", "id": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:06:38Z", "verificationMethod": "https://vc.example/issuers/56783#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": [ "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54" ], "proofValue": "z2hcFbMaj3BJufikuLZQ36gAXVT9J3ZiwB9rqN3j7VdqyT1GaQPbMTaF1Q2gn7h75ZcJ6JpV9pvNoDumvcjtmSRAV" }
The signed proof options
above gets appended to the allProofs
variable, which then gets set as the proof
attribute of the unsigned document
to produce the final signed document as shown below.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": [ { "type": "DataIntegrityProof", "id": "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56781#z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "proofPurpose": "assertionMethod", "proofValue": "z5KTX5yikM4eUukZW9qh66LGT3KZEUCACGpWcT2t4Yd54NMoFRchGmH4778omyNFAD3weSt6sNk5fuaMQmhhzNmEC" }, { "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod", "proofValue": "z5KXNyXDcm822dHS37tmS6Xc7FFNo8c73AfeqmfHoywPxnXWNjWKYK3VQzt3CMUoK9uAqsboVHKJXxuYwbdnfxZeA" }, { "type": "DataIntegrityProof", "id": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:06:38Z", "verificationMethod": "https://vc.example/issuers/56783#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": [ "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54" ], "proofValue": "z2hcFbMaj3BJufikuLZQ36gAXVT9J3ZiwB9rqN3j7VdqyT1GaQPbMTaF1Q2gn7h75ZcJ6JpV9pvNoDumvcjtmSRAV" } ] }
This collection of test vectors demonstrates construction of an extended proof
chain. We start with the output of the previous section and add an additional
proof that is dependent on one of the existing proofs. This example uses
keyPair4
, and the starting document is given below.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": [ { "type": "DataIntegrityProof", "id": "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56781#z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "proofPurpose": "assertionMethod", "proofValue": "z5KTX5yikM4eUukZW9qh66LGT3KZEUCACGpWcT2t4Yd54NMoFRchGmH4778omyNFAD3weSt6sNk5fuaMQmhhzNmEC" }, { "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod", "proofValue": "z5KXNyXDcm822dHS37tmS6Xc7FFNo8c73AfeqmfHoywPxnXWNjWKYK3VQzt3CMUoK9uAqsboVHKJXxuYwbdnfxZeA" }, { "type": "DataIntegrityProof", "id": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:06:38Z", "verificationMethod": "https://vc.example/issuers/56783#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": [ "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54" ], "proofValue": "z2hcFbMaj3BJufikuLZQ36gAXVT9J3ZiwB9rqN3j7VdqyT1GaQPbMTaF1Q2gn7h75ZcJ6JpV9pvNoDumvcjtmSRAV" } ] }
The options
input to
Section 4.4: Add Proof Set/Chain in [VC-DATA-INTEGRITY]
is shown below. Note that it includes a previousProof
attribute since we are
constructing a proof chain, however this time it is a single value.
{ "type": "DataIntegrityProof", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:16:38Z", "verificationMethod": "https://vc.example/issuers/56784#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23" }
Per the algorithm of
Section 4.4: Add Proof Set/Chain in [VC-DATA-INTEGRITY],
we create an array variable, allProofs, and add the proofs from the
starting document to it. Since the options
contains the previousProof
attribute, we compute the matchingProofs variable per step 4
of Section 4.4: Add Proof
Set/Chain, and we set the
unsecuredDocument.proof equal to the matchingProofs. This
produces the document shown below.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": [ { "type": "DataIntegrityProof", "id": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:06:38Z", "verificationMethod": "https://vc.example/issuers/56783#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": [ "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54" ], "proofValue": "z2hcFbMaj3BJufikuLZQ36gAXVT9J3ZiwB9rqN3j7VdqyT1GaQPbMTaF1Q2gn7h75ZcJ6JpV9pvNoDumvcjtmSRAV" } ] }
In step 6, we use the previous document (unsecured document with previous proofs
added to it) to compute the proofValue
attribute. This gives the signed
configuration options (proof) shown below:
{ "type": "DataIntegrityProof", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:16:38Z", "verificationMethod": "https://vc.example/issuers/56784#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "proofValue": "z6f4Lx4xiwWq8sucv6pg2vVvD5R4bxr58q2TagpwDXCxPVVS28S1iFwhor4ikhG6u4RKrNx7uSkYrCHdiiw5Js3d" }
The signed proof options
above gets appended to the allProofs
variable, which then gets set as the proof
attribute of the unsigned document
to produce the final signed document as shown below.
{ "@context": [ "https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2" ], "id": "urn:uuid:58172aac-d8ba-11ed-83dd-0b3aef56cc33", "type": [ "VerifiableCredential", "AlumniCredential" ], "name": "Alumni Credential", "description": "A minimum viable example of an Alumni Credential.", "issuer": "https://vc.example/issuers/5678", "validFrom": "2023-01-01T00:00:00Z", "credentialSubject": { "id": "did:example:abcdefgh", "alumniOf": "The School of Examples" }, "proof": [ { "type": "DataIntegrityProof", "id": "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56781#z6MktgKTsu1QhX6QPbyqG6geXdw6FQCZBPq7uQpieWbiQiG7", "proofPurpose": "assertionMethod", "proofValue": "z5KTX5yikM4eUukZW9qh66LGT3KZEUCACGpWcT2t4Yd54NMoFRchGmH4778omyNFAD3weSt6sNk5fuaMQmhhzNmEC" }, { "type": "DataIntegrityProof", "id": "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-24T23:36:38Z", "verificationMethod": "https://vc.example/issuers/56782#z6MkhWqdDBPojHA7cprTGTt5yHv5yUi1B8cnXn8ReLumkw6E", "proofPurpose": "assertionMethod", "proofValue": "z5KXNyXDcm822dHS37tmS6Xc7FFNo8c73AfeqmfHoywPxnXWNjWKYK3VQzt3CMUoK9uAqsboVHKJXxuYwbdnfxZeA" }, { "type": "DataIntegrityProof", "id": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:06:38Z", "verificationMethod": "https://vc.example/issuers/56783#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": [ "urn:uuid:26329423-bec9-4b2e-88cb-a7c7d9dc4544", "urn:uuid:8cc9022b-6b14-4cf3-8571-74972c5feb54" ], "proofValue": "z2hcFbMaj3BJufikuLZQ36gAXVT9J3ZiwB9rqN3j7VdqyT1GaQPbMTaF1Q2gn7h75ZcJ6JpV9pvNoDumvcjtmSRAV" }, { "type": "DataIntegrityProof", "cryptosuite": "eddsa-rdfc-2022", "created": "2023-02-26T22:16:38Z", "verificationMethod": "https://vc.example/issuers/56784#z6MkmEq87wkHCYnWnNZkigeDMGTN7oUw1upkhzd77KuXERS1", "proofPurpose": "assertionMethod", "previousProof": "urn:uuid:d94f792a-c546-4d06-b38a-da070ab56c23", "proofValue": "z6f4Lx4xiwWq8sucv6pg2vVvD5R4bxr58q2TagpwDXCxPVVS28S1iFwhor4ikhG6u4RKrNx7uSkYrCHdiiw5Js3d" } ] }
This section is non-normative.
This section contains the substantive changes that have been made to this specification over time.
Changes since the First Public Working Draft:
Referenced in:
Referenced in: