This package implements the Off-The-Record Messaging protocol in pure python. Off-The-Record Messaging (OTR) is a cryptographic protocol that provides encryption for instant messaging conversations. OTR uses a combination of AES symmetric-key algorithm with 128 bits key length, the Diffie-Hellman key exchange with 1536 bits group size, and the SHA-1/SHA-256 hash functions. Features of the OTR protocol: 1. End-to-end encryption: No one else can read your messages. 2. Authentication: The correspondent's identity can be verified. 3. Deniability: The messages you send do not have digital signatures that can be checked by a third party. Anyone can forge messages after a conversation to make them look like they came from you, however during the conversation your correspondent is assured that the messages he sees coming from you are authentic and unmodified. 4. Perfect forward secrecy: If you lose control of your private keys, you are assured that no previous conversation is compromised. This package implements the version 2 and 3 of the OTR protocol. For more details see https://otr.cypherpunks.ca/