Off-the-Record Messaging


Off-the-Record Messaging is a cryptographic protocol that provides encryption for Instant Messaging Applications.

Off-the-Record Messaging 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 hash Function. In addition to authentication and encryption, Off-the-Record Messaging provides Perfect Forward Secrecy and Homomorphic Encryption.

The primary motivation behind the protocol was providing Repudiation for the conversation participants while keeping conversations confidential, like a private conversation in real life, or off the record in journalism sourcing. This is in contrast with cryptography tools that produce output which can be later used as a verifiable record of the communication event and non-Repudiation identities of the participants.

The Off-the-Record Messaging protocol was designed by cryptographers Ian Goldberg and Nikita Borisov and released on 26 October 2004.[2] They provide a client library to facilitate support for instant messaging client developers who want to implement the protocol. A Pidgin and Kopete plugin exists that allows OTR to be used over any IM protocol supported by Pidgin or Kopete, offering an auto-detection feature that starts the OTR session with the buddies that have it enabled, without interfering with regular, unencrypted conversations.

Off-the-Record Messaging provides:[2]

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