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Make call encryption keys work: array shape + room-event transport - #32
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The io.element.call.encryption_keys wire format (MSC3401 / Element Call
/ FluffyChat) carries keys as an array of {index, key}, but
mx_call_key_content() emitted and mx_call_key_parse() read it as a
single object. Off the wire the Olm plaintext is parsed with
simplifyVector = FALSE, so keys arrived as a list of lists, $index was
NULL, and the parser dropped every real key event: a peer's audio
decrypted to silence (e2ee_state_changed MISSING_KEY) and our own key
reached no one. The tests encoded the same wrong object shape, so they
passed against it.
mx_call_key_content() now wraps the entry so it serializes as an array;
mx_call_key_parse() reads the array (tolerating a data frame or a lone
object) and returns one entry per key, so a single event can carry
several indices; mx_call_handle() applies each. Tests use a spec-shaped
event parsed with simplifyVector = FALSE, the exact shape that
regressed.
FluffyChat / matrix-dart-sdk distributes the call encryption key as an encrypted ROOM event with a top-level device_id, not a to-device event. mx_crypto_process_sync() dropped type and content from decrypted room events, so the key was unreachable even after it was decrypted, and mx_call_handle() only looked at to-device: the bot received the caller's audio but had no key and decoded silence. - mx_crypto_process_sync(): decrypted room-event records keep their inner type and content (additive; text consumers still read body). - mx_call_handle(): reads call keys from processed$events (room events in the call's room) as well as to_device. - mx_call_key_parse(): accepts the room-event shape (top-level device_id, room taken from the event) alongside the to-device shape. - mx_call_key_content(): superset carrying both device_id and member, so one object serves either transport. - mx_call_send_key(): also posts the key as an encrypted room event (guarded) so FluffyChat can decrypt the bot; mx_send_encrypted() gained an event_type argument.
A leftover title/description block from the previous edit attached to the internal helper, generating a stray man page and a roxygen undocumented-parameter warning.
TroyHernandez
changed the title
mx_call_send_key posts our key as a room event; the homeserver echoes it back in our own sync, where mx_call_handle's processed$events scan picked it up and applied our own key to our own participant slot. Skip parsed entries whose identity is the call's own.
A peer can open several Olm sessions to us and reply on any of them. The single inbound slot per peer was overwritten by each new session, so a message on a replaced session failed to decrypt and was dropped silently (a FluffyChat call key arrived on a session the bot had replaced, leaving the caller's audio MISSING_KEY). olm_in now holds a list of inbound sessions per peer curve25519; mx_crypto_process_sync appends new inbound sessions rather than overwriting, and olm_receive tries them all plus the outbound session. Legacy single-session stores load unchanged. The 'cannot decrypt Olm to-device message' warning now reports the message type, how many sessions were tried, and the create_inbound error for a failed prekey, so a dropped message is diagnosable.
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Make MatrixRTC call encryption keys actually work, found during the first live FluffyChat↔bot call: the bot connected, subscribed to the caller's audio, received frames, but every frame was undecryptable (
e2ee_state_changed MISSING_KEY) because no peer key was ever applied.Two independent bugs, both in the call-key path:
1.
keysis an array, not an object. Theio.element.call.encryption_keyscontent carrieskeysas an array of{index, key}.mx_call_key_content()emitted it as a single object andmx_call_key_parse()read it as one; off the wire the Olm/megolm plaintext is parsed withsimplifyVector = FALSE, sokeysarrives as a list of lists,$indexis NULL, and every real key event was dropped. The tests encoded the same wrong shape, so they passed against it.2. FluffyChat sends the key as a room event, not to-device. matrix-dart-sdk distributes the call key as an encrypted room event with a top-level
device_id.mx_crypto_process_sync()flattened every decrypted room event to a text-message record, droppingtypeandcontent, so the key was unreachable even once decrypted; andmx_call_handle()only readto_device.Changes:
mx_call_key_content():keysserializes as an array; superset content carrying both top-leveldevice_id(FluffyChat) and thememberblock (Element Call), so one object serves either transport.mx_call_key_parse(): reads the array (toleratingsimplifyVector = FALSElist-of-lists, a data frame, and a lone object), accepts both the to-device shape (member.claimed_device_id, contentroom_id) and the room-event shape (top-leveldevice_id, room from the event); returns one entry per key.mx_crypto_process_sync(): decrypted room-event records keep their innertypeandcontent(additive; text consumers still readbody).mx_call_handle(): applies call keys fromprocessed$events(room events in the call's room) as well asto_device.mx_call_send_key(): also posts the key as an encrypted room event (guarded) so FluffyChat can decrypt the bot;mx_send_encrypted()gained anevent_typeargument.Tests: spec-shaped events parsed with
simplifyVector = FALSE(the exact regressed shape), to-device and room-event shapes, multi-key events, object tolerance, handle reading room-event keys, and a serialization check thatkeysis a JSON array. 935 pass. Version 0.2.1.2.