chirp-identity.ts

1// Local-device identity helpers for the chirp-sync architecture.2//3// `deviceId` is a stable UUID v4 generated on first call and persisted in4// `chrome.storage.sync` so it roams across browser-profile reinstalls.5//6// `deviceName` defaults to a short, friendly browser+OS description and7// can be overridden by the user from Settings → Sync.8//9// The local sync identity itself is derived deterministically from the10// vault master key (`deriveSyncIdentityKeypair`); the function below is a11// thin coordinator that pulls the master key out of `vault.ts` and exposes12// only the public half to callers that don't need to sign.1314import { deriveSyncIdentityKeypair, pubkeyToHex } from "../shared/sync-identity";15import type { DeviceType } from "../shared/sync-types";1617const DEVICE_ID_KEY = "peach_chirp_device_id";18const DEVICE_NAME_KEY = "peach_chirp_device_name";1920export interface LocalChirpIdentity {21  deviceId: string;22  deviceName: string;23  deviceType: DeviceType;24  longTermPublicKeyHex: string;25}2627export async function getOrCreateDeviceId(): Promise<string> {28  const result = await chrome.storage.sync.get(DEVICE_ID_KEY);29  const current = (result as Record<string, unknown>)[DEVICE_ID_KEY];30  if (typeof current === "string" && current.length > 0) return current;31  const fresh = generateUuidV4();32  await chrome.storage.sync.set({ [DEVICE_ID_KEY]: fresh });33  return fresh;34}3536export async function getDeviceName(): Promise<string> {37  const result = await chrome.storage.sync.get(DEVICE_NAME_KEY);38  const stored = (result as Record<string, unknown>)[DEVICE_NAME_KEY];39  if (typeof stored === "string" && stored.length > 0) return stored;40  return defaultDeviceName();41}4243export async function setDeviceName(name: string): Promise<void> {44  const trimmed = name.trim();45  if (!trimmed) throw new Error("device name must not be empty");46  if (trimmed.length > 64) throw new Error("device name must be 64 chars or fewer");47  await chrome.storage.sync.set({ [DEVICE_NAME_KEY]: trimmed });48}4950/**51 * Build the public-facing identity record for the local extension. The52 * private key half (used only for ongoing Noise XX sessions) is not53 * exposed by this function — Phase-1 pairing uses ephemeral keys only.54 */55export async function buildLocalIdentity(56  masterKey: Uint8Array,57): Promise<LocalChirpIdentity> {58  const deviceId = await getOrCreateDeviceId();59  const deviceName = await getDeviceName();60  const kp = deriveSyncIdentityKeypair(masterKey, deviceId);61  return {62    deviceId,63    deviceName,64    deviceType: extensionDeviceType(),65    longTermPublicKeyHex: pubkeyToHex(kp.publicKey),66  };67}6869/**70 * Return the local sync identity keypair (public and private). Reserved71 * for the Phase-2 WebSocket sync coordinator that runs in the background.72 * Never surface the private key over a message handler.73 */74export function deriveLocalSyncKeypair(masterKey: Uint8Array, deviceId: string) {75  return deriveSyncIdentityKeypair(masterKey, deviceId);76}7778function defaultDeviceName(): string {79  // Best-effort browser + platform string. Avoids userAgent parsing — the80  // user can rename via Settings.81  const ua = (typeof navigator !== "undefined" ? navigator.userAgent : "") || "";82  if (/Firefox/i.test(ua)) return "Firefox";83  if (/Edg\//i.test(ua)) return "Edge";84  if (/Chrome/i.test(ua)) return "Chrome";85  if (/Safari/i.test(ua)) return "Safari";86  return "Browser";87}8889function extensionDeviceType(): DeviceType {90  // The same module ships in both the Chrome extension and the Capacitor91  // mobile build. On Capacitor, Peach acts as an iOS / Android sync host92  // rather than an extension; the `isNativePlatform` check toggles the tag.93  try {94    const native = (globalThis as unknown as { Capacitor?: { isNativePlatform?: () => boolean } }).Capacitor;95    if (native?.isNativePlatform?.()) {96      const platform = (globalThis as unknown as { Capacitor?: { getPlatform?: () => string } }).Capacitor?.getPlatform?.();97      if (platform === "ios") return "ios";98      return "android";99    }100  } catch { /* not on Capacitor */ }101  return "extension";102}103104function generateUuidV4(): string {105  // crypto.randomUUID is available in MV3 service workers, popup pages,106  // and modern Capacitor WebView. Falls back to a manual assembly only if107  // a runtime is missing it (effectively unreachable for our targets).108  if (typeof crypto !== "undefined" && typeof crypto.randomUUID === "function") {109    return crypto.randomUUID();110  }111  const bytes = new Uint8Array(16);112  crypto.getRandomValues(bytes as Uint8Array<ArrayBuffer>);113  bytes[6] = (bytes[6] & 0x0f) | 0x40;114  bytes[8] = (bytes[8] & 0x3f) | 0x80;115  const hex = Array.from(bytes, (b) => b.toString(16).padStart(2, "0")).join("");116  return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}`;117}