public key infrastructure

n. (abbr. PKI) The underlying systems and processes necessary to support the trustworthiness and wide-scale use of public key encryption to authenticate individuals in a digital environment, especially over the Internet.


Certificate authorities (CAs) are key components of PKI. They serve as a trusted third party that certifies that someone using a public key is, in fact, the person he or she claims to be. A CA issues an X.509 digital certificate that serves as an identification card, and the CA offers a service to validate its digital certificates. PKI defines the encryption techniques, identification procedures, and other processes necessary for the system to be trustworthy.