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Implementing Signal's Double Ratchet algorithm (2020)

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 used with each message. The algorithm comes at a nice time, when consumers are becoming more privacy-aware and governments more determined to perform mass surveillance, which is where E2E encryption becomes the only way to protect your data.

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. The algorithm comes at a nice time, when consumers are becoming more privacy-aware and governments more determined to perform mass surveillance, which is where E2E encryption becomes the only way to protect your data. Double Ratchet is used by the biggest platforms in the field, such as Signal, Facebook Messenger, WhatsApp and Matrix in order to provide E2E encryption for their instant messages.

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