The SKE protocol is used to establish session key and other security parameters for protecting the SILC Packet protocol. The SKE itself is based on the Diffie–Hellman key exchange algorithm (a form of asymmetric cryptography) and the exchange is protected with digital signatures. The SILC Authentication protocol is performed after successful SKE protocol execution to authenticate a client and/or a server. The authentication may be based on passphrase or on digital signatures, and if successful gives access to the relevant SILC network. The SILC Packet protocol is intended to be a secure binary packet protocol, assuring that the content of each packet (consisting of a packet header and packet payload) is secured and authenticated. The packets are secured using algorithms based on symmetric cryptography and authenticated by using Message Authentication Code algorithm, HMAC.