TLS Overview

Transport Layer Security (TLS) is used for two primary purposes:

• authentication of an end device (client or server) using a digital signature (DS)

  TLS uses PKI for device authentication. DSs are used to authenticate the client or the server. The server typically sends a certificate with a DS to the client.

  In specific situations, the server can request a certificate from the client to authenticate it. The client has a certificate (called a trust anchor) from the certificate authority (CA) that is used to authenticate the server certificate and its DS. After the client provides a digitally signed certificate to the server and both parties are authenticated, the encryption PDUs can then be transmitted.

• encryption and authentication of application PDUs

  After the client and server have been successfully authenticated, the cipher suite is negotiated between the server and clients, and the PDUs are encrypted based on the agreed cipher protocol.