Credentials in information systems are widely used to control access to information or other resources. The classic combination of a user account number or name and a secret password is a widely-used example of IT credentials.
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 unambiguous association of the credential with a specific, real individual or other entity. Cryptographic credentials are often designed to expire after a certain period, although this is not mandatory. An x.509 certificate is an example of a cryptographic credential.
An increasing number of information systems use other forms of documentation of credentials, such as Biometrics: fingerprints, voice recognition, retinal scans, Facial recognition systems1 , or X.509, Public key certificate, and so on.
