PKI 
Public Key Infrastructure 
A secure method for exchanging sensitive data or funds across the Internet. There is no single standard PKI, but the systems currently in use share the same basic elements: a certificate authority, which generates digital certificates that include the public key; a registration authority, which verifies the identities of all parties involved in a transaction; a directory where the certificates are kept; and a certificate management system. To send a secure message, a user requests a private key from a certificate authority, which generates a corresponding public key at the same time. The message's recipient uses the public key to decrypt the message. This same public key can be used to encrypt a response to the original message, and the recipient in this case would use the private key to decrypt it. VeriSign is an example of a PKI system.