Verifiable Claim

Full Title or Meme

A Verifiable Claim is one that can be Validated by a signed statement from some recognized authority as to the nature of a linkage between Attributes and a Subject.

Context

• The Context in which a validation applies should be made clear by a policy statement from the validating authorities.
• The mission of the Verifiable Claims Working Group (VCWG) is to make expressing and exchanging credentials that have been verified by a third party easier and more secure on the Web.

Problem

Granting a benefit requires proof and verification. Some benefits demand a formal process that includes three parties. In this process, the holder asks for the benefit and the inspector-verifier grants or denies the benefit based on verification of the holder’s qualification from a trusted issuer.

Solution

• A Verifiable Claims Data Model and Representations document is under development by the W3C Verifiable Claims working group on this GitHub site.
• It is hard to determine exactly what a verified claim is. It seems that it might only be verfied at the moment that a revocation check is made and not for one instant later, although that is not stated anywhere.
• There appears to be no way to link a verified claim to a user, or to prevent replay. It is not clear if all the members of the WG agree if that is the correct view.

Taxonomy from the spec

Name in spec	Name in this wiki	Definition
entity	in conflict	A thing with distinct and independent existence such as a person, organization, concept, or device.
subject	subject	An entity about which claims may be made.
claim	attribute	A statement made by an entity about a subject.
verifiable claim	Statement	claim that is effectively tamper-proof and whose authorship can be cryptographically verified, expressed in a standard, machine-readable data format which can also be extended with minimal coordination.
entity credential	in conflict	A set of one or more claims made by the same entity about a subject. (unclear how this is different from a verifiable claim)
issuer	issuer	An entity that creates a verifiable claim, associates it with a particular subject, and transmits it to a holder. Examples of issuers include corporations, governments, and individuals.
inspector-verifier	Attribute Provider	An entity that receives one or more verifiable claims for processing. Examples of inspector-verifiers include employers, security personnel, and websites.
identifier registry	Identifier Provider	Mediates the creation and verification of subject identifiers. Examples of identifier registries include corporate employee databases, government ID databases, and distributed ledgers.
Entity Profile	Trusted Identifier	information that, together with a subject identifier id, constitute an entity profile. The properties are not claims and are not intended to be verifiable.
Issued	Date	This is the date, in string format, when the claim was issued. (unclear - see example)
Type	Software in use	Determine the location's expected behavior
revocation	theoretically impossible	The value of this property must be a revocation scheme that provides enough information to determine whether or not the credential has been revoked. (this sounds like an OCSP)

Note that the term Identifier or Attribute Provider is used in this wiki as the distinction between identifiers and attributes is arbitrary and subject to interpretation.

EXAMPLE - A simple verifiable claim

Note that it is unclear on which date the claim "over 21" is valid. It seems that the issued date applies to the original credential and not this derived credential. If it is the date on which the claim became true, then it is releasing too much information.

{
  "@context": "https://w3id.org/security/v1",
  "id": "http://example.gov/credentials/3732",
  "type": ["Credential", "ProofOfAgeCredential"],
  "issuer": "https://dmv.example.gov",
  "issued": "2010-01-01",
  "claim": {
    "id": "did:example:ebfeb1f712ebc6f1c276e12ec21",
    "ageOver": 21
  },
  "revocation": {
    "id": "http://example.gov/revocations/738",
    "type": "SimpleRevocationList2017"
  },
  "signature": {
    "type": "LinkedDataSignature2015",
    "created": "2016-06-18T21:19:10Z",
    "creator": "https://example.com/jdoe/keys/1",
    "domain": "json-ld.org",
    "nonce": "598c63d6",
    "signatureValue": "BavEll0/I1zpYw8XNi1bgVg/sCneO4Jugez8RwDg/+
    MCRVpjOboDoe4SxxKjkCOvKiCHGDvc4krqi6Z1n0UfqzxGfmatCuFibcC1wps
    PRdW+gGsutPTLzvueMWmFhwYmfIFpbBu95t501+rSLHIEuujM/+PXr9Cky6Ed
    +W3JT24="
  }
}

References

1. Synonyms include: Assurance Attested Corroborated.