(PKI) A system of {public key encryption} using {digital certificates} from {Certificate Authorities} and other registration authorities that verify and authenticate the validity of each party involved in an electronic transaction. PKIs are currently evolving and there is no single PKI nor even a single agreed-upon standard for setting up a PKI. However, nearly everyone agrees that reliable PKIs are necessary before electronic commerce can become widespread. US DOD PKI . US NIST PKI . IETF PKIX Working Group . (1999-11-30)