sync-vault-adapter.ts

1// Production adapter that backs `runSyncInitiator` with the live vault.2//3// The coordinator (sync-coordinator.ts) never decrypts vault data; it4// only moves opaque base64 entry blobs and metadata. This adapter is the5// boundary where vault plaintext meets the sync layer — entries leave the6// vault as encrypted envelopes here, and incoming envelopes are decrypted7// here before being merged via `applyMergedRemoteEntries`.8//9// Envelope cipher: AES-GCM with a PER-ENTRY key derived as10//   HKDF-SHA256(ikm = syncMasterKey, salt = "", info = entryId + "\x00" + "sync-entry-v1")11// (random 12B nonce, aad = "peach-sync-entry-v1"). Binding the key to the12// entry id means a ciphertext minted for one entry slot cannot be replayed13// into another: decryptEntryOrNull rejects any envelope whose decrypted14// entry.id does not match the map key it arrived under. Both sides hold the15// same syncMasterKey (same vault) so keys match without prior negotiation. The16// Noise KK reconnect session encrypts the transport on top — the envelope is17// belt-and-braces so a transport-layer leak doesn't expose plaintext entries.18//19// Device-manifest exchange (v2 brief §4.3) is plumbed here. Any admitted20// mesh peer may issue one — see applyVerifiedPeerManifest for why the issuer21// is not restricted by device type or first-pair topology, and for what the22// Noise-authenticated static key gates. docs/mesh-vouching-authority.md is the23// end-to-end trace.2425import { HKDF } from "@stablelib/hkdf";26import { SHA256 } from "@stablelib/sha256";27import type { SyncVaultAdapter } from "./sync-coordinator";28import { getDeviceName, getOrCreateDeviceId } from "./device-identity";29import {30  computeVaultId,31  deriveSyncIdentityKeypair,32  deriveSyncSigningKeypair,33  hexToPubkey,34  pubkeyToHex,35} from "../shared/sync-identity";36import {37  buildSignedDeviceManifest,38  verifyDeviceManifest,39} from "../shared/device-manifest";40import { constantTimeEqualHex } from "../shared/constant-time";41import {42  applyMergedRemoteEntries,43  getTombstoneManifest,44  getRootKeyHex,45  getEntries,46  getEntryById,47  getVaultVersion,48  isUnlocked,49} from "./vault";50import {51  findPairedDeviceById,52  findPairedDeviceByPubkey,53  isDeviceRevoked,54  listDeviceRevocations,55  listPairedDevices,56  mergeDeviceRevocations,57  removePairedDeviceById,58  upsertPairedDevice,59} from "./paired-devices";60import {61  removePendingVouchedDevice,62} from "./pending-vouched-devices";63import {64  bytesToHex as rendezvousBytesToHex,65  deriveMeshRendezvousSecret,66  normalizeRelayUrl,67} from "../shared/rendezvous";68import { recordSyncAlerts } from "./sync-alerts";69import { SYNC_LIMITS, clampSyncTimestamp } from "../shared/sync-limits";70import type { VaultEntry } from "../shared/types";71import type {72  ManifestDeviceEntry,73  PairedDevice,74  SignedDeviceManifest,75} from "../shared/sync-types";76import { replaceLockedSyncSpool, drainLockedSyncInbox } from "./locked-sync-spool";7778// Each entry uses a unique AES-GCM key: HKDF(masterKey, info = entryId + "\x00" + "sync-entry-v1").79// The info binding prevents a ciphertext from one entry slot being replayed into another.80const ENTRY_KEY_INFO_SUFFIX = "sync-entry-v1";81const ENTRY_AAD = "peach-sync-entry-v1";8283export class VaultLockedError extends Error {84  constructor() {85    super("vault_locked");86    this.name = "VaultLockedError";87  }88}8990export function createSyncVaultAdapter(91  context: { deviceName?: string } = {},92): SyncVaultAdapter {93  return {94    async computeVaultId() {95      const master = requireMasterKey();96      return computeVaultId(master);97    },9899    async getOurDeviceId() {100      return getOrCreateDeviceId();101    },102103    async getLocalVersion() {104      return getVaultVersion();105    },106107    async buildEntryManifest() {108      requireUnlocked();109      const manifest: Record<string, number> = {};110      for (const entry of getEntries()) {111        manifest[entry.id] = entry.modifiedAt;112      }113      return manifest;114    },115116    async buildTombstoneManifest() {117      requireUnlocked();118      return getTombstoneManifest();119    },120121    async getEncryptedEntries(entryIds) {122      requireUnlocked();123      const masterKey = requireMasterKey();124      const out: Record<string, string> = {};125      for (const id of entryIds) {126        const entry = getEntryById(id);127        if (!entry) continue;128        const key = await deriveEntryKey(masterKey, id);129        out[id] = await encryptEntry(key, entry);130      }131      return out;132    },133134    async applyEntries(entries) {135      requireUnlocked();136      const entryList = Object.entries(entries);137      // MV-3: bound the batch before any per-entry crypto work.138      if (entryList.length > SYNC_LIMITS.MAX_ENTRY_COUNT) {139        throw new Error(140          `sync entry count ${entryList.length} exceeds limit ${SYNC_LIMITS.MAX_ENTRY_COUNT}`,141        );142      }143      const masterKey = requireMasterKey();144      const decrypted: VaultEntry[] = [];145      for (const [id, envelope] of entryList) {146        // MV-3: per-entry ceiling, checked on the (base64) envelope before147        // decrypting. Base64 inflates by 4/3, so allow that factor.148        if (envelope.length > (SYNC_LIMITS.MAX_ENTRY_PLAINTEXT_BYTES * 4) / 3 + 64) {149          continue; // oversized envelope — skip, never decrypt150        }151        const key = await deriveEntryKey(masterKey, id);152        const entry = await decryptEntryOrNull(key, envelope);153        if (!entry) continue;154        // MV-3: defense in depth — re-measure the decrypted plaintext.155        if (JSON.stringify(entry).length > SYNC_LIMITS.MAX_ENTRY_PLAINTEXT_BYTES) {156          continue;157        }158        // The map key is the authority on id — refuse mismatched envelopes159        // so a swapped envelope can't poison a different entry slot.160        if (entry.id !== id) continue;161        decrypted.push(entry);162      }163      if (decrypted.length > 0) {164        await applyMergedRemoteEntries(decrypted, {}, context);165      }166    },167168    async applyTombstones(tombstones) {169      requireUnlocked();170      const tombstoneList = Object.entries(tombstones);171      // MV-3: bound the tombstone batch before processing.172      if (tombstoneList.length > SYNC_LIMITS.MAX_TOMBSTONE_COUNT) {173        throw new Error(174          `sync tombstone count ${tombstoneList.length} exceeds limit ${SYNC_LIMITS.MAX_TOMBSTONE_COUNT}`,175        );176      }177      const cleaned: Record<string, number> = {};178      for (const [id, ts] of tombstoneList) {179        if (typeof ts === "number" && Number.isFinite(ts) && ts > 0) {180          // HV-1c: clamp before the value participates in any comparison.181          // vault.ts clamps again defensively; clamping here keeps the182          // invariant local to the boundary where peer data enters.183          cleaned[id] = clampSyncTimestamp(ts);184        }185      }186      if (Object.keys(cleaned).length > 0) {187        await applyMergedRemoteEntries([], cleaned, context);188      }189    },190191    async buildOutgoingDeviceManifest() {192      requireUnlocked();193      const masterKey = requireMasterKey();194      const issuerDeviceId = await getOrCreateDeviceId();195      const signing = await deriveSyncSigningKeypair(masterKey, issuerDeviceId);196      const revoked = await listDeviceRevocations();197      const revokedIds = new Set(revoked.map((r) => r.deviceId));198      const devices = (await listPairedDevices())199        .filter((d) => !revokedIds.has(d.deviceId))200        .map(toManifestEntry)201        .filter((d): d is ManifestDeviceEntry => d !== null);202      return buildSignedDeviceManifest(203        issuerDeviceId,204        devices,205        signing.privateKey,206        { revoked },207      );208    },209210    async applyIncomingDeviceManifest(manifest, authenticatedRemoteStaticPublicKey) {211      requireUnlocked();212      await applyVerifiedPeerManifest(213        manifest,214        authenticatedRemoteStaticPublicKey,215      );216    },217  };218}219220export async function refreshLockedSyncSpool(): Promise<void> {221  requireUnlocked();222  const masterKey = requireMasterKey();223  const deviceId = await getOrCreateDeviceId();224  const identity = await buildCachedIdentity(masterKey, deviceId);225  const cachedEntries: Record<string, { modifiedAt: number; ciphertext: string }> = {};226  try {227    for (const entry of getEntries()) {228      if (entry.deletedAt) continue;229      const key = await deriveEntryKey(masterKey, entry.id);230      cachedEntries[entry.id] = {231        modifiedAt: entry.modifiedAt,232        ciphertext: await encryptEntry(key, entry),233      };234    }235    const tombstones = getTombstoneManifest();236    const { longTermPrivateKeyBytes: _privateKeyBytes, longTermPrivateKeyHex: _privateKeyHex, ...storedIdentity } = identity;237    await replaceLockedSyncSpool({238      ...storedIdentity,239      localVersion: await getVaultVersion(),240      entries: cachedEntries,241      tombstones,242    });243  } finally {244    masterKey.fill(0);245    identity.longTermPrivateKeyBytes.fill(0);246  }247}248249export async function drainAndRefreshLockedSyncSpool(): Promise<void> {250  const live = createSyncVaultAdapter();251  await drainLockedSyncInbox(live);252  await refreshLockedSyncSpool();253}254255async function buildCachedIdentity(masterKey: Uint8Array, deviceId: string) {256  const vaultId = await computeVaultId(masterKey);257  const keys = deriveSyncIdentityKeypair(masterKey, deviceId);258  const deviceName = await getDeviceName();259  return {260    vaultId,261    deviceId,262    deviceName,263    deviceType: "extension" as const,264    longTermPublicKeyHex: pubkeyToHex(keys.publicKey),265    longTermPrivateKeyHex: bytesToHex(keys.secretKey),266    longTermPrivateKeyBytes: keys.secretKey,267  };268}269270function toManifestEntry(device: PairedDevice): ManifestDeviceEntry | null {271  if (272    !device.deviceId ||273    !device.deviceName ||274    !device.deviceType ||275    !device.longTermPublicKeyHex ||276    !/^[0-9a-f]{64}$/.test(device.longTermPublicKeyHex) ||277    !device.signingPublicKeyHex ||278    !/^[0-9a-f]{64}$/.test(device.signingPublicKeyHex)279  ) {280    return null;281  }282  return {283    deviceId: device.deviceId,284    deviceName: device.deviceName,285    deviceType: device.deviceType,286    longTermPublicKeyHex: device.longTermPublicKeyHex,287    signingPublicKeyHex: device.signingPublicKeyHex,288    wsPort: device.wsPort,289    relayUrl: device.relayUrl,290    pairedAt: device.pairedAt,291  };292}293294/**295 * Apply a device manifest issued by a peer we pair with directly.296 *297 * The issuer used to be required to be an "extension", on the assumption that298 * the extension was the mesh's trust anchor. It is not: the device a fresh299 * install joins through is the one holding the peer list to hand over.300 *301 * The issuer must already be admitted locally as either direct or vouched.302 * That is the decentralisation boundary: an unknown key has no session and no303 * authority, while every authenticated member can propagate the same signed304 * pool without the original hub online. A v3 entry is admitted only when it305 * carries a valid relay route; both endpoints independently derive the same306 * pair-only capability from their vault root and public keys.307 */308async function applyVerifiedPeerManifest(309  manifest: SignedDeviceManifest,310  authenticatedRemoteStaticPublicKey: Uint8Array,311): Promise<void> {312  const issuerId = manifest?.body?.issuerDeviceId;313  if (typeof issuerId !== "string" || !issuerId) { return; }314315  if (authenticatedRemoteStaticPublicKey.length !== 32) {316    return;317  }318  const authenticatedPubkeyHex = pubkeyToHex(authenticatedRemoteStaticPublicKey);319  const issuer = await findPairedDeviceByPubkey(authenticatedPubkeyHex);320  if (321    !issuer ||322    issuer.deviceId !== issuerId ||323    (324      issuer.trustSource !== "direct" &&325      issuer.trustSource !== "vouched"326    ) ||327    !issuer.signingPublicKeyHex ||328    !/^[0-9a-f]{64}$/.test(issuer.signingPublicKeyHex)329  ) {330    return;331  }332333  let body: Awaited<ReturnType<typeof verifyDeviceManifest>>;334  try {335    body = await verifyDeviceManifest(336      manifest,337      hexToPubkey(issuer!.signingPublicKeyHex!),338    );339  } catch {340    // Stored key may be stale (older builds persisted the key derived at341    // first-pair and never refreshed it). The signing keypair is deterministic342    // from (masterKey, deviceId) on both sides, so retry once with the locally343    // re-derived pubkey. A genuinely forged signature throws here and is344    // silently rejected — only a stale-but-correct key survives the retry.345    const masterForIssuer = requireMasterKey();346    try {347      const derived = await deriveSyncSigningKeypair(348        masterForIssuer,349        issuer.deviceId,350      );351      body = await verifyDeviceManifest(manifest, derived.publicKeyRaw);352    } catch {353      return;354    } finally {355      masterForIssuer.fill(0);356    }357  }358  if (body.issuerDeviceId !== issuer.deviceId) {359    return;360  }361362  const ourDeviceId = await getOrCreateDeviceId();363  const masterKey = requireMasterKey();364  const localKeys = deriveSyncIdentityKeypair(masterKey, ourDeviceId);365366  try {367    // Revocations are absorbed BEFORE any vouching, so a manifest that both368    // revokes and re-vouches the same device in one payload cannot race itself.369    // A peer may not revoke US — that would let one compromised device sever the370    // whole mesh — so our own id is filtered out first.371    const newlyRevoked = await mergeDeviceRevocations(372      body.revoked.filter((r) => r.deviceId !== ourDeviceId),373    );374    for (const deviceId of newlyRevoked) {375      await removePairedDeviceById(deviceId);376      await removePendingVouchedDevice(deviceId);377      void recordSyncAlerts([378        {379          type: "DEVICE_REVOKED",380          entryId: "",381          entryTitle: deviceId,382          deviceName: issuer.deviceName ?? "paired device",383          timestamp: Date.now(),384        },385      ]);386    }387388    for (const entry of body.devices) {389      if (entry.deviceId === ourDeviceId || entry.deviceId === issuer.deviceId) {390        continue;391      }392      // Terminal: no manifest re-admits a revoked device. Matched on the key as393      // well as the id, because the id is the issuer's to choose — checking only394      // the id let a revoked key walk back in under a fresh one. The check sits395      // ahead of the existing-device lookup so it also refuses rotating a device396      // we still trust onto a revoked key.397      if (await isDeviceRevoked(entry.deviceId, entry.longTermPublicKeyHex)) {398        continue;399      }400      const existing = await findPairedDeviceById(entry.deviceId);401      const meshRoute = deriveManifestMeshRoute(402        masterKey,403        localKeys.publicKey,404        entry,405      );406407      // A v3 manifest from an admitted, KK-authenticated issuer proves408      // same-vault membership and carries enough route material for the two409      // introduced endpoints to derive their own capability. Admit it410      // immediately so a six-device vault converges without keeping the411      // original pairing hub online.412      if (!existing) {413        if (!meshRoute) continue;414        await upsertPairedDevice({415          deviceId: entry.deviceId,416          deviceName: entry.deviceName,417          deviceType: entry.deviceType,418          longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),419          signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),420          wsPort: entry.wsPort,421          rendezvousSecretHex: meshRoute.rendezvousSecretHex,422          relayUrl: meshRoute.relayUrl,423          pairedAt: entry.pairedAt,424          trustSource: "vouched",425        });426        await removePendingVouchedDevice(entry.deviceId);427        continue;428      }429430      // MV-8d: a key changing under a stable deviceId is legitimate after a431      // reinstall, but it is exactly what a graph-poisoning attack looks like —432      // signal the user either way, durably (the alert queue survives a closed433      // popup) and live (the broadcast updates an open one).434      if (435        existing.longTermPublicKeyHex &&436        !constantTimeEqualHex(437          existing.longTermPublicKeyHex,438          entry.longTermPublicKeyHex,439        )440      ) {441        // S5: name the device from the LOCAL record, never from the manifest.442        // The issuer is a third party here (its own entry is skipped above), so443        // `entry.deviceName` is an unverified claim about someone else — an444        // attacker who could put it on screen could make its own key rotation445        // read as a rotation on a device the user trusts more.446        const knownName = existing.deviceName ?? entry.deviceName;447        notifyPopup({448          type: "DEVICE_KEY_ROTATED",449          payload: { deviceName: knownName, deviceId: entry.deviceId },450        });451        void recordSyncAlerts([452          {453            type: "DEVICE_KEY_ROTATED",454            entryId: "",455            entryTitle: knownName,456            deviceName: knownName,457            timestamp: Date.now(),458          },459        ]);460      }461462      // Existing device — update in place as before. The name is deliberately463      // NOT taken from the manifest: a device's name is set by that device at464      // pairing, and letting a third-party issuer rewrite it is the rename-then-465      // impersonate half of S5. Self-renames never arrive here anyway.466      await upsertPairedDevice({467        ...existing,468        deviceId: entry.deviceId,469        deviceName: existing.deviceName ?? entry.deviceName,470        deviceType: entry.deviceType,471        longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),472        signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),473        pairedAt: existing.pairedAt ?? entry.pairedAt,474        trustSource: existing.trustSource,475        wsPort: existing.wsPort ?? entry.wsPort,476        rendezvousSecretHex:477          existing.trustSource === "vouched" && meshRoute478            ? meshRoute.rendezvousSecretHex479            : existing.rendezvousSecretHex,480        relayUrl:481          existing.trustSource === "vouched" && meshRoute482            ? meshRoute.relayUrl483            : existing.relayUrl,484        lastSyncedAt: existing.lastSyncedAt,485      });486    }487  } finally {488    masterKey.fill(0);489    localKeys.secretKey.fill(0);490  }491}492493function deriveManifestMeshRoute(494  masterKey: Uint8Array,495  localPublicKey: Uint8Array,496  entry: ManifestDeviceEntry,497): { rendezvousSecretHex: string; relayUrl: string } | null {498  try {499    if (!entry.relayUrl) return null;500    const relayUrl = normalizeRelayUrl(entry.relayUrl);501    const secret = deriveMeshRendezvousSecret(502      masterKey,503      localPublicKey,504      hexToPubkey(entry.longTermPublicKeyHex),505    );506    try {507      return {508        rendezvousSecretHex: rendezvousBytesToHex(secret),509        relayUrl,510      };511    } finally {512      secret.fill(0);513    }514  } catch {515    return null;516  }517}518519function notifyPopup(msg: { type: string; payload?: unknown }): void {520  try {521    void chrome.runtime.sendMessage(msg).catch(() => undefined);522  } catch {523    /* popup closed — the durable sync-alert queue remains authoritative */524  }525}526527function requireUnlocked(): void {528  if (!isUnlocked()) throw new VaultLockedError();529}530531// Sync derives everything — vault_id, the Noise static key, the Ed25519532// manifest signing key, and the per-entry envelope keys — from the vault's533// stable root key, NOT the password-derived key. This keeps paired devices'534// identities and envelope keys constant across a master-password change on535// either side (SEV-2-B); two paired devices with independently-rotated536// passwords still share this key and can decrypt each other's entries.537function requireMasterKey(): Uint8Array {538  if (!isUnlocked()) throw new VaultLockedError();539  const hex = getRootKeyHex();540  if (!hex) throw new VaultLockedError();541  return hexToBytes(hex);542}543544async function deriveEntryKey(masterKey: Uint8Array, entryId: string): Promise<CryptoKey> {545  // Null-byte separator (HKDF hardening): entryId cannot contain \x00, so this546  // makes the (entryId, suffix) boundary unambiguous regardless of future id547  // formats. Coordinated wire change — peach-android VaultSyncAdapter derives548  // the identical info; the two MUST stay byte-for-byte in lockstep.549  const info = new TextEncoder().encode(`${entryId}\x00${ENTRY_KEY_INFO_SUFFIX}`);550  const raw = new HKDF(SHA256, masterKey, new Uint8Array(0), info).expand(32);551  return crypto.subtle.importKey(552    "raw",553    raw.buffer as ArrayBuffer,554    { name: "AES-GCM" },555    false,556    ["encrypt", "decrypt"],557  );558}559560async function encryptEntry(key: CryptoKey, entry: VaultEntry): Promise<string> {561  const plaintext = new TextEncoder().encode(JSON.stringify(entry));562  const nonce = crypto.getRandomValues(new Uint8Array(12));563  const aad = new TextEncoder().encode(ENTRY_AAD);564  const ct = await crypto.subtle.encrypt(565    {566      name: "AES-GCM",567      iv: nonce.buffer as ArrayBuffer,568      additionalData: aad.buffer as ArrayBuffer,569      tagLength: 128,570    },571    key,572    plaintext.buffer as ArrayBuffer,573  );574  const ctBytes = new Uint8Array(ct);575  const envelope = new Uint8Array(nonce.length + ctBytes.length);576  envelope.set(nonce, 0);577  envelope.set(ctBytes, nonce.length);578  return bytesToBase64(envelope);579}580581async function decryptEntryOrNull(key: CryptoKey, envelopeB64: string): Promise<VaultEntry | null> {582  try {583    const bytes = base64ToBytes(envelopeB64);584    if (bytes.length < 12 + 16) return null;585    const nonce = bytes.subarray(0, 12);586    const ct = bytes.subarray(12);587    const aad = new TextEncoder().encode(ENTRY_AAD);588    const pt = await crypto.subtle.decrypt(589      {590        name: "AES-GCM",591        iv: nonce.buffer.slice(nonce.byteOffset, nonce.byteOffset + nonce.byteLength) as ArrayBuffer,592        additionalData: aad.buffer as ArrayBuffer,593        tagLength: 128,594      },595      key,596      ct.buffer.slice(ct.byteOffset, ct.byteOffset + ct.byteLength) as ArrayBuffer,597    );598    const json = new TextDecoder().decode(pt);599    const parsed = JSON.parse(json);600    if (!parsed || typeof parsed !== "object" || typeof parsed.id !== "string") return null;601    return parsed as VaultEntry;602  } catch {603    return null;604  }605}606607function hexToBytes(hex: string): Uint8Array {608  if (hex.length % 2 !== 0) throw new Error("hex length must be even");609  const out = new Uint8Array(hex.length / 2);610  for (let i = 0; i < out.length; i++) {611    out[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);612  }613  return out;614}615616function bytesToBase64(bytes: Uint8Array): string {617  let bin = "";618  for (let i = 0; i < bytes.length; i++) bin += String.fromCharCode(bytes[i]);619  return btoa(bin);620}621622function bytesToHex(bytes: Uint8Array): string {623  return Array.from(bytes, (byte) => byte.toString(16).padStart(2, "0")).join("");624}625626function base64ToBytes(b64: string): Uint8Array {627  const bin = atob(b64);628  const out = new Uint8Array(bin.length);629  for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i);630  return out;631}