A credential is an arbitrary amount of data input. Credentials in cryptography establish the identity of a party to communication. Usually, they take the form of machine-readable cryptographic keys and/or passwords. Cryptographic credentials may be self-issued, or issued by a trusted third party; in many cases, the only criterion for issuance is the unambiguous association of the credential with a specific, real individual or other entity.
Cryptographic credentials are means to implement secure privacy protecting certificates in decentralized systems. Cryptographic credentials are often designed to expire after a certain period, although this is not mandatory.
An X.509 public key certificate is an example of a cryptographic credential.