libsignal [WIP]

This go library is an implementation of the signal asynchronous messaging protocol modified for use in OpenBazaar.

Modifications include:

• Removed all communication with the signal servers. This library only handles session state management, encryption, and decryption. It's up to you to implement a transport for the ciphertext.
• Removed prekey transport. Again, you need to implement a method of getting Alice's prekey bundle to Bob so that Bob can send the first message.
• Removed message metadata. Messages are not tagged with the recipient ID. This allows them to be stored on untrusted servers without leaking metadata. The cost, however, is that to decrypt a message one must iterative over all open sessions to decrypt the message. Assuming the number of sessions a user keeps open at any given time is relatively small, this shouldn't have scaling issues. It may be possible to improve the efficiency here by tagging each message with a shared secret that ratchets forward, but at the cost of more complexity.
• [TODO] Identity keys switched to RSA (which is what OpenBazaar/IPFS uses).