SSL and TLS

SSL transmission protocol employs a cryptographic system that uses two keys to encrypt data: a public key known to everyone and a private, or secret, key known only to the recipient of the message. TLS is the successor to SSL.

Both protocols use X.509 certificates and asymmetric cryptography to identify the counterparty with whom they are talking, and to exchange a symmetric key. This session key is then used to encrypt data flowing between the parties, providing data and message confidentiality, along with message authentication codes for message integrity and message authentication. An important characteristic is PFS, so the short term session key cannot be derived from the long-term asymmetric secret key.