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W3C Verifiable Credentials

W3C Verifiable Credentials [1] (VCs) are a standardized way to represent claims about a subject in a secure, privacy-preserving manner. They enable individuals and organisations to present their credentials in a manner that is tamper-evident, cryptographically secure, and verifiable.

Key Features of W3C Verifiable Credentials​

  • Interoperability: VCs are based on open standards, ensuring they can be used across different systems and platforms.
  • Security: Credentials are digitally signed by issuers, making them tamper-evident and ensuring their authenticity.
  • Privacy: Holders can selectively disclose information from their credentials, protecting their privacy while proving the required claims.
  • Decentralization: VCs support decentralized identifiers (DIDs), reducing reliance on centralized authorities and enhancing user control.

Components of a Verifiable Credential​

  1. Issuer: The entity that creates and signs the credential.
  2. Holder: The entity that possesses the credential and can present it to verifiers.
  3. Verifier: The entity that checks the validity of the credential.

Core Concepts​

Verifiable Credentials (VC)​

A Verifiable Credential contains a set of claims made by an issuer about a subject, such as a person or enterprise. These claims are expressed in a tamper-evident and privacy-respecting manner, allowing them to be verified digitally.

Components of a Verifiable Credential​

  • Context (@context): Specifies the semantic context for the data.
  • Type (type): Identifies the type of credential.
  • Credential Subject (credentialSubject): Contains the claims about the subject.
  • Issuer (issuer): Identifies who issued the credential.
  • Issuance Date (validFrom): When the credential was issued.
  • Expiration Date (validUntil): (Optional) When the credential expires.
  • Proof (proof): Cryptographic proof to ensure the credential's integrity.

Example​

Example of a LPID W3C credential protected by a LD-Proof using a EcdsaSecp256r1Signature2019 signature.​

{
  "@context": ["https://www.w3.org/ns/credentials/v2", "https://oid.spherity.com/contexts/oid/v1.jsonld"],
  "type": ["VerifiableCredential", "LegalEntityCertificate"],
  "credentialSubject": {
    "id": "did:key:zDnaeyXvqvYVJhVBe2ysSQ2Z4LwW8L8ZWrkqzsczLTf8PjDGA",
    "type": "LegalPersonId",
    "euid": "HUOCCSZ12345678",
    "companyName": "Flower Power AG"
  },
  "issuer": "did:key:zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP",
  "validFrom": "2023-08-24T13:06:21Z",
  "proof": {
    "@context": "https://www.w3.org/ns/credentials/v2",
    "type": "EcdsaSecp256r1Signature2019",
    "created": "2023-08-24T13:06:21Z",
    "proofPurpose": "assertionMethod",
    "verificationMethod": "did:key:zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP#zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP",
    "proofValue": "8upuIPtJVkTkunL9/tKH/cgnVZweG1f8mdMaAdu7KG3zWqfQhKuHuwnjmUttBhdzDhfdVB1qSh/2pcXWgYdQ/w=="
  }
}

Verifiable Presentations (VP)​

A Verifiable Presentation is a collection of one or more Verifiable Credentials, optionally combined with additional information, which is shared by the holder to a verifier. The presentation is cryptographically verifiable to ensure its authenticity and integrity.

Components of a Verifiable Presentation​

  • Context (@context): Defines the semantic context for the presentation.
  • Type (type): Identifies the type of presentation.
  • Verifiable Credential (verifiableCredential): Contains one or more verifiable credentials.
  • Holder (holder): Identifies the entity presenting the credentials.
  • Proof (proof): Cryptographic proof to ensure the presentation's integrity.

Example​

Example Presentation​

{
  "@context": ["https://www.w3.org/ns/credentials/v2", "https://oid.spherity.com/contexts/oid/v1.jsonld"],
  "type": ["VerifiablePresentation"],
  "verifiableCredential": [
    {
      "@context": [
        "https://www.w3.org/ns/credentials/v2",
        "https://oid.spherity.com/contexts/oid/v1.jsonld"
      ],
      "type": ["VerifiableCredential", "LegalEntityCertificate"],
      "credentialSubject": {
        "id": "did:key:zDnaeyXvqvYVJhVBe2ysSQ2Z4LwW8L8ZWrkqzsczLTf8PjDGA",
        "type": "LegalPersonId",
        "euid": "HUOCCSZ12345678",
        "companyName": "Flower Power AG"
      },
      "issuer": "did:key:zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP",
      "validFrom": "2023-08-24T13:06:21Z",
      "proof": {
        "@context": "https://www.w3.org/ns/credentials/v2",
        "type": "EcdsaSecp256r1Signature2019",
        "created": "2023-08-24T13:06:21Z",
        "proofPurpose": "assertionMethod",
        "verificationMethod": "did:key:zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP#zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP",
        "proofValue": "8upuIPtJVkTkunL9/tKH/cgnVZweG1f8mdMaAdu7KG3zWqfQhKuHuwnjmUttBhdzDhfdVB1qSh/2pcXWgYdQ/w=="
      }
    }
  ],
  "holder": "did:example:ebfeb1f712ebc6f1c276e12ec21",
  "proof": {
    "@context": "https://www.w3.org/ns/credentials/v2",
    "type": "EcdsaSecp256r1Signature2019",
    "created": "2023-08-24T13:06:21Z",
    "proofPurpose": "authentication",
    "verificationMethod": "did:key:zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP#zDnaepBuvsQ8cpsWrVKw8fbpGpvPeNSjVPTWoq6cRqaYzBKVP",
    "proofValue": "8upuIPtJVkTkunL9/tKH/cgnVZweG1f8mdMaAdu7KG3zWqfQhKuHuwnjmUttBhdzDhfdVB1qSh/2pcXWgYdQ/w=="
  }
}

Using Verifiable Credentials in OID application:​

In our Enterprise Wallet, we leverage W3C Verifiable Credentials to manage and present credentials securely including selective disclosure. We use the following libraries from digitalbazar for creating, verifying, and managing credentials:

  • @digitalbazaar/data-integrity - Verify json-ld data integrity (using jsonld-signatures)
  • @digitalbazaar/did-method-key - Library for creating and resolving DID documents using the key method.
  • @digitalbazaar/ecdsa-multikey - Library for creating ECDSA multikeys and verifying signatures created from those
  • @digitalbazaar/ecdsa-sd-2023-cryptosuite
    • Create Verifiable Credentials: Easily define and issue credentials with cryptographic proofs.
    • Verify Credentials: Check the authenticity and integrity of received credentials.
    • Create Verifiable Presentations: Combine multiple credentials into a single presentation for sharing.
    • Selective Disclosure: Allow holders to share only the necessary information from their credentials.

References​

  1. World Wide Web Consortium (W3C) (2024), Verifiable Credentials Data Model v2.0, Available at: https://www.w3.org/TR/vc-data-model-2.0/ (Accessed at: July 9, 2024).