X.509 Certificate – The X.509 public-key certificate or the X.509 attribute certificate, as defined by the ISO/ITU-T X.509 standard. Most commonly (including in this document), an X.509 certificate refers to the X.509 public-key certificate. (SP 800-57 Part 1) (NISTIR)
A digital certificate containing a public key for entity and a name for the entity, together with some other information that is rendered unforgeable by the digital signature of the certification authority that issued the certificate, encoded in the format defined in the ISO/ITU-T X.509 standard. (SP 800-57 Part 1; CNSSI-4009 adapted) (NISTIR)
