Validity Period
A validity period defines the time range during which a verifiable credential is considered valid. It provides temporal context for credential claims and helps verifiers determine current applicability.
Validity Period Components
Section titled “Validity Period Components”The W3C Verifiable Credentials Data Model (VCDM) specification defines two primary properties to express the validity period:
validFrom
Section titled “validFrom”The validFrom property defines when a credential becomes valid. It uses XML Schema dateTimeStamp (RFC 3339 format with timezone), such as "2010-01-01T19:23:24Z". This optional property represents the earliest point when the credential is valid.
validUntil
Section titled “validUntil”The validUntil property defines when a credential ceases to be valid. It uses the same dateTimeStamp format and can be omitted for credentials without expiration.
When both properties are present, validFrom must be temporally the same or earlier than validUntil, ensuring logical consistency.
Default Behavior
Section titled “Default Behavior”If neither property is present, the validity period is indefinite. If only validFrom exists, the credential is valid from that time onward. If only validUntil exists, validity is assumed from creation until that time.
Validation Considerations
Section titled “Validation Considerations”During verification, the current time is compared with the validity period. A credential is temporally valid if the current time is equal to or later than validFrom (if present) and earlier than validUntil (if present).
Privacy Implications
Section titled “Privacy Implications”Short-lived credentials require frequent renewal, creating correlation risks as issuers track renewal timing. They provide better freshness but may compromise privacy.
Long-lived credentials reduce renewal frequency, offering better privacy but requiring more complex revocation mechanisms.
Examples
Section titled “Examples”Example 1: Credential with Both Properties
Section titled “Example 1: Credential with Both Properties”{ "@context": ["https://www.w3.org/ns/credentials/v2", "https://www.w3.org/ns/credentials/examples/v2"], "id": "http://university.example/credentials/3732", "type": ["VerifiableCredential", "ExampleDegreeCredential"], "issuer": "https://university.example/issuers/14", "validFrom": "2010-01-01T19:23:24Z", "validUntil": "2020-01-01T19:23:24Z", "credentialSubject": { "id": "did:example:ebfeb1f712ebc6f1c276e12ec21", "degree": { "type": "ExampleBachelorDegree", "name": "Bachelor of Science and Arts" } }}