https://ci.appveyor.com/project/southernsun/otr

This is an attempt to implement the Off-the-Record Messaging protocol in .NET

Currently, the following tools are implemented:

• otr_parse
• otr_sesskeys
• otr_mackey

! Please read the following section carefully

This project is under active development and not yet ready for release.

Current limitations/shortcomings:

• This project is under active development and not yet ready for release and therefore not yet ready or not sufficiently tested to use for secure chat.
• Strings stored within memory are not cleared/wiped after use and are therefore vulnerable for a (cross) process memory attack.
• many more...!!

From the original Off-the-Record Messaging website:

What is Off-the-Record (OTR) Messaging

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.

Original website: http://www.cypherpunks.ca/otr/