Off-the-Record (OTR) Messaging allows you to have private conversations over instant messaging by providing: * Encryption No one else can read your instant messages. * Authentication You are assured the correspondent is who you think it is. * Deniability The messages you send do not have digital signatures that are checkable by a third party. Anyone can forge messages after a conversation to make them look like they came from you. However, during a conversation, your correspondent is assured the messages he sees are authentic and unmodified. * Perfect forward secrecy If you lose control of your private keys, no previous conversation is compromised.
WWW: http://otr.cypherpunks.ca/