Re-apply Simon's emebdded e2ee work on latest livekit branch

Replaces https://github.com/vector-im/element-call/pull/1350

src/livekit/useLiveKit.ts

@@ -26,6 +26,7 @@ import { useLiveKitRoom } from "@livekit/components-react";
 import { useEffect, useMemo, useRef, useState } from "react";
 import E2EEWorker from "livekit-client/e2ee-worker?worker";
 import { logger } from "matrix-js-sdk/src/logger";
+import { MatrixRTCSession } from "matrix-js-sdk/src/matrixrtc/MatrixRTCSession";
 
 import { defaultLiveKitOptions } from "./options";
 import { SFUConfig } from "./openIDSFU";
@@ -39,9 +40,16 @@ import {
   ECConnectionState,
   useECConnectionState,
 } from "./useECConnectionState";
+import { MatrixKeyProvider } from "../e2ee/matrixKeyProvider";
+
+export enum E2EEMode {
+  PerParticipantKey = "per_participant_key",
+  SharedKey = "shared_key",
+}
 
 export type E2EEConfig = {
-  sharedKey: string;
+  mode: E2EEMode;
+  sharedKey?: string;
 };
 
 interface UseLivekitResult {
@@ -50,26 +58,38 @@ interface UseLivekitResult {
 }
 
 export function useLiveKit(
+  rtcSession: MatrixRTCSession,
   muteStates: MuteStates,
   sfuConfig?: SFUConfig,
   e2eeConfig?: E2EEConfig,
 ): UseLivekitResult {
-  const e2eeOptions = useMemo(() => {
-    if (!e2eeConfig?.sharedKey) return undefined;
+  const e2eeOptions = useMemo((): E2EEOptions | undefined => {
+    if (!e2eeConfig) return undefined;
 
-    return {
-      keyProvider: new ExternalE2EEKeyProvider(),
-      worker: new E2EEWorker(),
-    } as E2EEOptions;
+    if (e2eeConfig.mode === E2EEMode.PerParticipantKey) {
+      return {
+        keyProvider: new MatrixKeyProvider(),
+        worker: new E2EEWorker(),
+      };
+    } else if (e2eeConfig.mode === E2EEMode.SharedKey && e2eeConfig.sharedKey) {
+      return {
+        keyProvider: new ExternalE2EEKeyProvider(),
+        worker: new E2EEWorker(),
+      };
+    }
   }, [e2eeConfig]);
 
   useEffect(() => {
-    if (!e2eeConfig?.sharedKey || !e2eeOptions) return;
+    if (!e2eeConfig || !e2eeOptions) return;
 
-    (e2eeOptions.keyProvider as ExternalE2EEKeyProvider).setKey(
-      e2eeConfig?.sharedKey,
-    );
-  }, [e2eeOptions, e2eeConfig?.sharedKey]);
+    if (e2eeConfig.mode === E2EEMode.PerParticipantKey) {
+      (e2eeOptions.keyProvider as MatrixKeyProvider).setRTCSession(rtcSession);
+    } else if (e2eeConfig.mode === E2EEMode.SharedKey && e2eeConfig.sharedKey) {
+      (e2eeOptions.keyProvider as ExternalE2EEKeyProvider).setKey(
+        e2eeConfig.sharedKey,
+      );
+    }
+  }, [e2eeOptions, e2eeConfig, rtcSession]);
 
   const initialMuteStates = useRef<MuteStates>(muteStates);
   const devices = useMediaDevices();