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.