pqc-ratchet — Post-Quantum Secure Messaging Demo

Ready — establish a session or run the auto demo

X3DH + Double Ratchet demo. Both sides generate fresh ML-KEM-768 + ML-DSA-65 keypairs in your browser. X3DH derives a shared root key — no secret is transmitted. A session PIN (SHA-256 of both exchange keys) lets both parties verify they're talking to the right identity before trusting. Then watch the KEM ratchet advance with each reply.

Establish session via X3DH

Alice → "Hello Bob, testing pqc-ratchet"

Alice → "Second message, same ratchet epoch"

Bob → "Hi Alice! (new KEM epoch — ratchet advances)"

Bob → "Second reply, epoch continues"

Alice → "Back to Alice — another new epoch"

Bob → "Final message — epoch 3"

Alice Initiator

Session PIN

— — — — · — — — —

✓ matches Bob

DSA pub — Exchange — Root key — Chain — Ratchet pub —

received messages appear here

Bob Responder

Session PIN

— — — — · — — — —

✓ matches Alice

DSA pub — Exchange — Root key — Chain — Ratchet pub —

received messages appear here

Protocol Wire Log 0 events click any entry to expand wire bytes

Establish a session to see the protocol wire log

How it works in code full program for both sides · ~50 lines total · active block highlights as demo runs ▼

Alice initiator — sends the PreKeyMessage

Bob responder — receives and replies