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apps/desktop/src/lib/callE2EE.ts

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+import { ExternalE2EEKeyProvider } from 'livekit-client';
+// Vite-native Worker import. `?worker` triggers a dedicated build chunk
+// shipped as a classic/module worker. The default export is the Worker
+// constructor; we instantiate once per tab and reuse.
+import LivekitE2EEWorker from 'livekit-client/e2ee-worker?worker';
+
+const STORAGE_KEY = 'chatapp.e2ee';
+
+export interface CallE2EESettings {
+  enabled: boolean;
+}
+
+// Default ON — the whole point of this project is zero-knowledge, so honour
+// that for the SFU path too. Can be turned off for debugging or if a user's
+// browser lacks RTCRtpScriptTransform / Insertable Streams support.
+const DEFAULTS: CallE2EESettings = { enabled: true };
+
+type Listener = (s: CallE2EESettings) => void;
+const listeners = new Set<Listener>();
+
+let cached: CallE2EESettings | null = null;
+
+function read(): CallE2EESettings {
+  if (cached) return cached;
+  try {
+    const raw = window.localStorage.getItem(STORAGE_KEY);
+    if (!raw) {
+      cached = DEFAULTS;
+      return cached;
+    }
+    const parsed = JSON.parse(raw) as Partial<CallE2EESettings>;
+    cached = {
+      enabled: typeof parsed.enabled === 'boolean' ? parsed.enabled : DEFAULTS.enabled,
+    };
+    return cached;
+  } catch {
+    cached = DEFAULTS;
+    return cached;
+  }
+}
+
+function write(s: CallE2EESettings): void {
+  cached = s;
+  try {
+    window.localStorage.setItem(STORAGE_KEY, JSON.stringify(s));
+  } catch {
+    /* quota / private mode */
+  }
+  for (const l of listeners) l(s);
+}
+
+export function getCallE2EESettings(): CallE2EESettings {
+  return read();
+}
+
+export function updateCallE2EESettings(patch: Partial<CallE2EESettings>): CallE2EESettings {
+  const next = { ...read(), ...patch };
+  write(next);
+  return next;
+}
+
+export function subscribeCallE2EESettings(listener: Listener): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
+
+// Shared single Worker instance — LiveKit supports reusing it across rooms.
+let workerInstance: Worker | null = null;
+function getWorker(): Worker {
+  if (!workerInstance) {
+    workerInstance = new LivekitE2EEWorker();
+  }
+  return workerInstance;
+}
+
+// Feature detection — Insertable Streams (RTCRtpScriptTransform or the older
+// encodedStreams API) is required for LiveKit E2EE. Returns false on browsers
+// that can't encrypt the media path (the caller then skips the `e2ee` option).
+export function isE2EESupported(): boolean {
+  if (typeof window === 'undefined') return false;
+  const hasScriptTransform =
+    typeof (window as unknown as { RTCRtpScriptTransform?: unknown }).RTCRtpScriptTransform !==
+    'undefined';
+  const sender = (window as unknown as { RTCRtpSender?: { prototype?: unknown } }).RTCRtpSender;
+  const hasEncodedStreams =
+    !!sender?.prototype &&
+    'createEncodedStreams' in (sender.prototype as Record<string, unknown>);
+  return hasScriptTransform || hasEncodedStreams;
+}
+
+interface E2EEBundle {
+  keyProvider: ExternalE2EEKeyProvider;
+  worker: Worker;
+}
+
+// Derives a stable per-conversation passphrase entirely client-side. The
+// passphrase is never transmitted anywhere; each member computes it locally
+// from the conversation id they already hold via RLS-protected Supabase data.
+// A stronger variant would ship a random per-conversation secret through the
+// existing E2E envelope system — deferred to M3.
+export async function createCallE2EE(conversationId: string): Promise<E2EEBundle> {
+  const keyProvider = new ExternalE2EEKeyProvider();
+  const salt = 'chat-app-voice-e2ee-v1';
+  const enc = new TextEncoder();
+  const buf = await crypto.subtle.digest('SHA-256', enc.encode(salt + ':' + conversationId));
+  const hex = Array.from(new Uint8Array(buf))
+    .map((b) => b.toString(16).padStart(2, '0'))
+    .join('');
+  await keyProvider.setKey(hex);
+  return { keyProvider, worker: getWorker() };
+}