Transport Layer Security pre-shared key ciphersuites (TLS-PSK) is a set of cryptographic protocols that provide secure communication based on pre-shared keys (PSKs). These pre-shared keys are symmetric keys shared in advance among the communicating parties.
There are several ciphersuites: The first set of ciphersuites uses only symmetric key operations for authentication. The second set uses a Diffie-Hellman key exchange authenticated with a pre-shared key. The third set combines public key authentication of the server with pre-shared key authentication of the client.
Usually, Transport Layer Security (TLS) uses public key certificates or Kerberos for authentication. TLS-PSK uses symmetric keys, shared in advance among the communicating parties, to establish a TLS connection. There are several reasons to use PSKs: