"type": "VerificationKeyConfirmation"
+ Implementers are advised to pay close attention to the extension points in this specification, such as in Sections , -, ,, -, and . While this +, , +, , +, and . While this specification does not define concrete implementations for those extension points, the Verifiable Credentials Extension Registry [[?VC-EXTENSION-REGISTRY]] provides an unofficial, curated list of extensions that developers can use from @@ -2905,6 +2915,149 @@
+An issuer can include a Confidence Method in a verifiable +credential to inform verifiers of mechanisms they could use to increase +their confidence in the truth of a variety of things, including the +following:
+
+A verifier can decide to accept claims in a verifiable
+credential without requiring use of the confidence method, or use a
+different mechanism to increase their confidence about whether, for
+example, the holder is the same entity the issuer made
+claims about in the verifiable credential. Such a decision
+can impact the verifier's liability or lack thereof if not
+specified by other means such as a termsOfUse policy.
+
+This specification defines the confidenceMethod property
+for expressing confidence method information in a
+credentialSubject in a verifiable credential.
+
+For example, an issuer can include a confidence method based on public +key cryptography in the verifiable credential. A holder can +demonstrate they are able to generate and include a proof with a +cryptographic signature in the verifiable presentation that will verify +against the verification key expressed in the confidence method in the +embedded verifiable credential. +
+
+A verifier can validate that the holder controls,
+or has been designated the ability to use, a confidence method
+by verifying the proof of the verifiable
+presentation using the information in the confidence method. The
+confidence method can include the verification key, or the type of the
+confidence method can define that the verification key is to be inferred from
+other properties in the verifiable credential, such as the
+credentialSubject.id.
+
+If present, the value of the confidenceMethod property is
+one or more confidence methods. Each confidence method is bound to one or more
+claims in the verifiable credential, and provides enough information for a
+verifier to determine whether the holder can generate a
+verifiable presentation to increase the verifier's confidence
+that they are the same entity referenced by the confidence method.
+This is referred to as satisfying the confidence method. It is required that
+the issuer verifies the holder can satisfy each
+confidenceMethod the issuer includes in the
+claims of the verifiable credentials they issue.
+
+Each confidence method MUST specify its type and MAY specify an
+id. The precise properties and semantics of each
+confidence method are determined by the specific
+confidenceMethod type definition.
+
+The following example demonstrates a confidence method based on proving +possession of a cryptographic key. The corresponding public key is a +type-specific property of the confidence method. +
+ +
+{
+ "@context": [
+ "https://www.w3.org/ns/credentials/v2",
+ "https://www.w3.org/ns/credentials/examples/v2"
+ ],
+ "id": "http://example.edu/credentials/3732",
+ "type": ["VerifiableCredential", "UniversityDegreeCredential"],
+ "issuer": "https://example.edu/issuers/14",
+ "validFrom": "2010-01-01T19:23:24Z",
+ "credentialSubject": {
+ "confidenceMethod": [{
+ "type": "VerificationKeyConfirmation",
+ "publicKeyJwk": {
+ "crv": "Ed25519",
+ "x": "VCpo2LMLhn6iWku8MKvSLg2ZAoC-nlOyPVQaO3FxVeQ",
+ "kty": "OKP",
+ "kid": "_Qq0UL2Fq651Q0Fjd6TvnYE-faHiOpRlPVQcY_-tA4A"
+ }
+ },{
+ "type": "VerificationKeyConfirmation",
+ "publicKeyMultibase": "zH3C2AVvLMv6gmMNam3uVAjZpfkcJCwDwnZn6z3wXmqPV"
+ }],
+ "degree": {
+ "type": "BachelorDegree",
+ "name": "Bachelor of Science and Arts"
+ }
+ },
+ "proof": { ... }
+}
+
+
+ +A confidence method can express various metadata such as the issuer's +level of confidence that the holder is the entity referenced by a +subject of the verifiable credential, specific form factors or +mechanisms of authenticators, and/or references to other verifiable credentials +or versioned trust frameworks. For example, an issuer can make a +claim about a confidence method that is based on a cryptographic key +pair, but to produce a signature using that key, the holder has to unlock +a device using multi-factor authentication. +
+ +