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fix: Use per-participant E2EE mode (no shared_key)

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shared_key locks provider in shared-key mode, making set_key()
ineffective for per-participant decryption. Remove shared_key so
SDK initializes in per-participant mode. Also: failure_tolerance=-1
to prevent premature track closure on decrypt failures,
ratchet_window_size=16 to match Element Call.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
This commit is contained in:
Christian Gick
2026-02-22 07:00:22 +02:00
parent c290332a1e
commit 9ebf90c8bb
1 changed files with 9 additions and 8 deletions
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17
voice.py
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@@ -69,16 +69,17 @@ def _generate_lk_jwt(room_id, user_id, device_id):
KDF_HKDF = 1 KDF_HKDF = 1
def _build_e2ee_options(shared_key: bytes) -> rtc.E2EEOptions: def _build_e2ee_options() -> rtc.E2EEOptions:
"""Build HKDF E2EE options matching Element Call's key derivation. """Build HKDF E2EE options matching Element Call's key derivation.
Element Call uses: ratchetWindowSize=10, keyringSize=256, salt="LKFrameEncryptionKey" No shared_key — initializes in per-participant mode so set_key() works.
Element Call uses: ratchetWindowSize=16, keyringSize=256, salt="LKFrameEncryptionKey"
""" """
key_opts = rtc.KeyProviderOptions( key_opts = rtc.KeyProviderOptions(
shared_key=shared_key, shared_key=None,
ratchet_window_size=10, ratchet_window_size=16,
ratchet_salt=b"LKFrameEncryptionKey", ratchet_salt=b"LKFrameEncryptionKey",
failure_tolerance=10, failure_tolerance=-1,
key_ring_size=256, key_ring_size=256,
key_derivation_function=KDF_HKDF, key_derivation_function=KDF_HKDF,
) )
@@ -209,9 +210,9 @@ class VoiceSession:
break break
await asyncio.sleep(0.1) await asyncio.sleep(0.1)
# Connect with E2EE enabled using bot's key as initial shared_key # Connect with E2EE in per-participant mode (no shared_key)
# (required to initialize encryption framework, we override per-participant after) # so set_key() calls work correctly for both directions
e2ee_opts = _build_e2ee_options(self._bot_key) e2ee_opts = _build_e2ee_options()
room_opts = rtc.RoomOptions(e2ee=e2ee_opts) room_opts = rtc.RoomOptions(e2ee=e2ee_opts)
self.lk_room = rtc.Room() self.lk_room = rtc.Room()