I’ve been reading up on the Double Ratchet algorithm and its implementations lately, as it’s an exciting piece of crypto that offers some very nice guarantees: forward secrecy (ie. by breaking a key at some point you can’t read older messages), eventual break-in recovery (ie. by breaking a key you can only read a few messages before the protocol recovers), and of course confidentiality and deniability. It’s all done through the use of “ratchets”, which are used to update the key u...
