Off-the-Record (OTR) Messaging 可以让你在即时通讯上发起私密对话。
提供的功能包括：
加密
No one else can read your instant messages.
认证
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.
