Signal Protocol

The gold standard for end-to-end encryption, providing cryptographic foundations for secure messaging through Double Ratchet and X3DH protocols.

Signal Protocol defines the modern benchmark for asynchronous encrypted communication. It combines the Double Ratchet algorithm for ongoing session security with the X3DH key agreement for initial handshakes, ensuring forward secrecy and post-compromise security. This architecture powers the privacy of 2 billion WhatsApp users, Google Messages, and the Signal app itself. By rotating keys after every message, the protocol guarantees that a single compromised key cannot unlock past or future conversations: a critical safeguard for global digital infrastructure.

https://signal.org/docs/