sorrydave 0.2.0

DAVE (Discord Audio/Video End-to-End Encryption) protocol library — pure data and state layer on rfc9420

sorrydave

Production-quality Python library for the DAVE (Discord Audio/Video End-to-End Encryption) protocol. It implements the protocol as a pure data-transformation and state-management layer on top of rfc9420 (PyMLS), with no I/O or networking: you pass in bytes (Voice Gateway opcodes, encoded media frames) and get back bytes (opcode payloads, encrypted/decrypted frames).

Features

• MLS integration: Key packages, external sender handling, proposals, commit/welcome (opcodes 25–30), exporter-based sender keys
• Sender key ratchet: Per-sender, per-epoch keys via MLS-Exporter + HKDF; cache for out-of-order decryption
• Frame transform: Codec-aware encrypt/decrypt (OPUS, VP9, VP8, H264, H265, AV1), ULEB128, truncated AES128-GCM, DAVE footer (0xFAFA)
• Identity: Pairwise fingerprint (scrypt) and displayable codes (45-digit / 30-digit)

Install

pip install -e .

Requires Python 3.9+, rfc9420, cryptography, and pycryptodome.

Minimal lifecycle

1. Create a session: DaveSession(local_user_id=123456789).
2. On select_protocol_ack (or prepare_epoch with epoch=1), call session.prepare_epoch(1) and send the returned bytes as opcode 26 (Key Package).
3. On opcode 25 (External Sender Package), call session.handle_external_sender_package(package_bytes).
4. On opcode 27 (Proposals), call session.handle_proposals(proposal_bytes); if it returns bytes, send them as opcode 28.
5. On opcode 29 (Announce Commit), call session.handle_commit(transition_id, commit_bytes).
6. On opcode 30 (Welcome), call session.handle_welcome(transition_id, welcome_bytes).
7. On opcode 22 (Execute Transition), parse with parse_execute_transition(payload) to get transition_id, then call session.execute_transition(transition_id).
8. Use session.get_encryptor().encrypt(frame, codec="OPUS") and session.get_decryptor(sender_id).decrypt(protocol_frame) for media.

Error recovery: On InvalidCommitError, send build_invalid_commit_welcome(transition_id) as opcode 31 to the voice gateway, then call session.prepare_epoch(1) and send the returned key package as opcode 26.

API overview

• DaveSession: handle_external_sender_package, prepare_epoch, handle_proposals, handle_commit, handle_welcome, execute_transition, leave_group, get_encryptor, get_decryptor
• FrameEncryptor.encrypt(encoded_frame, codec) / FrameDecryptor.decrypt(protocol_frame)
• generate_fingerprint(local_id, local_pub, remote_id, remote_pub) → 45-digit string
• displayable_code(data, total_digits, group_size) for epoch authenticator (e.g. 30 digits, group 5)

Scope

• In scope: MLS state, ratchet, OPUS/VP9/VP8/H264/H265/AV1 codec handling, frame encrypt/decrypt, identity fingerprint, opcode 22 parse and opcode 31 build for transition and error recovery.
• Out of scope: Voice Gateway WebSocket I/O, SFU silence packets, WebRTC depacketizer patches.

License

MIT.