When we say that Keychat uses the Signal protocol (X3DH + double ratchet algorithm), we mean that Keychat directly uses the Signal Foundation’s open-source libsignal (which is based on the Curve25519 algorithm), rather than reimplementing the double ratchet algorithm using nostr’s secp256k1 algorithm.

https://github.com/signalapp/libsignal nostr:note13yc8lcmfugllthnnxw3s899spl80w2wjegfzwle5n36y3rlj50uqg7fvak