SILC channels (groups) are protected by using symmetric channel keys. It is optionally possible to digitally sign all channel messages. It is also possible to protect messages with a privately generated channel key that has been previously agreed upon by channel members. Private messages between users in a SILC network are protected with session keys. It is, however, possible to execute SKE protocol between two users and use the generated key to protect private messages. Private messages may be optionally digitally signed. When messages are secured with key material generated with the SKE protocol or previously agreed upon key material (for example, passphrases) SILC provides security even when the SILC server may be compromised.