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 { 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  getDeletedEntries,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";7677// Each entry uses a unique AES-GCM key: HKDF(masterKey, info = entryId + "\x00" + "sync-entry-v1").78// The info binding prevents a ciphertext from one entry slot being replayed into another.79const ENTRY_KEY_INFO_SUFFIX = "sync-entry-v1";80const ENTRY_AAD = "peach-sync-entry-v1";8182export class VaultLockedError extends Error {83  constructor() {84    super("vault_locked");85    this.name = "VaultLockedError";86  }87}8889export function createSyncVaultAdapter(90  context: { deviceName?: string } = {},91): SyncVaultAdapter {92  return {93    async computeVaultId() {94      const master = requireMasterKey();95      return computeVaultId(master);96    },9798    async getOurDeviceId() {99      return getOrCreateDeviceId();100    },101102    async getLocalVersion() {103      return getVaultVersion();104    },105106    async buildEntryManifest() {107      requireUnlocked();108      const manifest: Record<string, number> = {};109      for (const entry of getEntries()) {110        manifest[entry.id] = entry.modifiedAt;111      }112      return manifest;113    },114115    async buildTombstoneManifest() {116      // KNOWN LIMITATION: tombstones accumulate without bound. Every deleted117      // entry leaves a {id, deletedAt} record that persists indefinitely and is118      // sent in every sync session, so a long-lived vault's manifest grows with119      // total deletions, not live entries. Acceptable for now (records are tiny120      // and the trash-retention purge eventually splices the entry array).121      // TODO(tombstone-gc): prune tombstones older than N months once every paired device122      // Algorithm: (1) After SYNC_DONE, record the peer-ack timestamp per tombstone.123      // (2) Once ALL paired devices have ack-ed a tombstone, splice it from the124      // deleted-entries array. (3) Gate on all-devices to prevent resurrection125      // from an offline peer that still holds the entry.126      requireUnlocked();127      const manifest: Record<string, number> = {};128      for (const entry of getDeletedEntries()) {129        if (typeof entry.deletedAt === "number") {130          manifest[entry.id] = entry.deletedAt;131        }132      }133      return manifest;134    },135136    async getEncryptedEntries(entryIds) {137      requireUnlocked();138      const masterKey = requireMasterKey();139      const out: Record<string, string> = {};140      for (const id of entryIds) {141        const entry = getEntryById(id);142        if (!entry) continue;143        const key = await deriveEntryKey(masterKey, id);144        out[id] = await encryptEntry(key, entry);145      }146      return out;147    },148149    async applyEntries(entries) {150      requireUnlocked();151      const entryList = Object.entries(entries);152      // MV-3: bound the batch before any per-entry crypto work.153      if (entryList.length > SYNC_LIMITS.MAX_ENTRY_COUNT) {154        throw new Error(155          `sync entry count ${entryList.length} exceeds limit ${SYNC_LIMITS.MAX_ENTRY_COUNT}`,156        );157      }158      const masterKey = requireMasterKey();159      const decrypted: VaultEntry[] = [];160      for (const [id, envelope] of entryList) {161        // MV-3: per-entry ceiling, checked on the (base64) envelope before162        // decrypting. Base64 inflates by 4/3, so allow that factor.163        if (envelope.length > (SYNC_LIMITS.MAX_ENTRY_PLAINTEXT_BYTES * 4) / 3 + 64) {164          continue; // oversized envelope — skip, never decrypt165        }166        const key = await deriveEntryKey(masterKey, id);167        const entry = await decryptEntryOrNull(key, envelope);168        if (!entry) continue;169        // MV-3: defense in depth — re-measure the decrypted plaintext.170        if (JSON.stringify(entry).length > SYNC_LIMITS.MAX_ENTRY_PLAINTEXT_BYTES) {171          continue;172        }173        // The map key is the authority on id — refuse mismatched envelopes174        // so a swapped envelope can't poison a different entry slot.175        if (entry.id !== id) continue;176        decrypted.push(entry);177      }178      if (decrypted.length > 0) {179        await applyMergedRemoteEntries(decrypted, {}, context);180      }181    },182183    async applyTombstones(tombstones) {184      requireUnlocked();185      const tombstoneList = Object.entries(tombstones);186      // MV-3: bound the tombstone batch before processing.187      if (tombstoneList.length > SYNC_LIMITS.MAX_TOMBSTONE_COUNT) {188        throw new Error(189          `sync tombstone count ${tombstoneList.length} exceeds limit ${SYNC_LIMITS.MAX_TOMBSTONE_COUNT}`,190        );191      }192      const cleaned: Record<string, number> = {};193      for (const [id, ts] of tombstoneList) {194        if (typeof ts === "number" && Number.isFinite(ts) && ts > 0) {195          // HV-1c: clamp before the value participates in any comparison.196          // vault.ts clamps again defensively; clamping here keeps the197          // invariant local to the boundary where peer data enters.198          cleaned[id] = clampSyncTimestamp(ts);199        }200      }201      if (Object.keys(cleaned).length > 0) {202        await applyMergedRemoteEntries([], cleaned, context);203      }204    },205206    async buildOutgoingDeviceManifest() {207      requireUnlocked();208      const masterKey = requireMasterKey();209      const issuerDeviceId = await getOrCreateDeviceId();210      const signing = await deriveSyncSigningKeypair(masterKey, issuerDeviceId);211      const revoked = await listDeviceRevocations();212      const revokedIds = new Set(revoked.map((r) => r.deviceId));213      const devices = (await listPairedDevices())214        .filter((d) => !revokedIds.has(d.deviceId))215        .map(toManifestEntry)216        .filter((d): d is ManifestDeviceEntry => d !== null);217      return buildSignedDeviceManifest(218        issuerDeviceId,219        devices,220        signing.privateKey,221        { revoked },222      );223    },224225    async applyIncomingDeviceManifest(manifest, authenticatedRemoteStaticPublicKey) {226      requireUnlocked();227      await applyVerifiedPeerManifest(228        manifest,229        authenticatedRemoteStaticPublicKey,230      );231    },232  };233}234235function toManifestEntry(device: PairedDevice): ManifestDeviceEntry | null {236  if (237    !device.deviceId ||238    !device.deviceName ||239    !device.deviceType ||240    !device.longTermPublicKeyHex ||241    !/^[0-9a-f]{64}$/.test(device.longTermPublicKeyHex) ||242    !device.signingPublicKeyHex ||243    !/^[0-9a-f]{64}$/.test(device.signingPublicKeyHex)244  ) {245    return null;246  }247  return {248    deviceId: device.deviceId,249    deviceName: device.deviceName,250    deviceType: device.deviceType,251    longTermPublicKeyHex: device.longTermPublicKeyHex,252    signingPublicKeyHex: device.signingPublicKeyHex,253    wsPort: device.wsPort,254    relayUrl: device.relayUrl,255    pairedAt: device.pairedAt,256  };257}258259/**260 * Apply a device manifest issued by a peer we pair with directly.261 *262 * The issuer used to be required to be an "extension", on the assumption that263 * the extension was the mesh's trust anchor. It is not: the device a fresh264 * install joins through is the one holding the peer list to hand over.265 *266 * The issuer must already be admitted locally as either direct or vouched.267 * That is the decentralisation boundary: an unknown key has no session and no268 * authority, while every authenticated member can propagate the same signed269 * pool without the original hub online. A v3 entry is admitted only when it270 * carries a valid relay route; both endpoints independently derive the same271 * pair-only capability from their vault root and public keys.272 */273async function applyVerifiedPeerManifest(274  manifest: SignedDeviceManifest,275  authenticatedRemoteStaticPublicKey: Uint8Array,276): Promise<void> {277  const issuerId = manifest?.body?.issuerDeviceId;278  if (typeof issuerId !== "string" || !issuerId) return;279280  if (authenticatedRemoteStaticPublicKey.length !== 32) return;281  const authenticatedPubkeyHex = pubkeyToHex(authenticatedRemoteStaticPublicKey);282  const issuer = await findPairedDeviceByPubkey(authenticatedPubkeyHex);283  if (284    !issuer ||285    issuer.deviceId !== issuerId ||286    (287      issuer.trustSource !== "direct" &&288      issuer.trustSource !== "vouched"289    ) ||290    !issuer.signingPublicKeyHex ||291    !/^[0-9a-f]{64}$/.test(issuer.signingPublicKeyHex)292  ) {293    return;294  }295296  let body: Awaited<ReturnType<typeof verifyDeviceManifest>>;297  try {298    body = await verifyDeviceManifest(299      manifest,300      hexToPubkey(issuer.signingPublicKeyHex),301    );302  } catch {303    return;304  }305  if (body.issuerDeviceId !== issuer.deviceId) return;306307  const ourDeviceId = await getOrCreateDeviceId();308  const masterKey = requireMasterKey();309  const localKeys = deriveSyncIdentityKeypair(masterKey, ourDeviceId);310311  try {312    // Revocations are absorbed BEFORE any vouching, so a manifest that both313    // revokes and re-vouches the same device in one payload cannot race itself.314    // A peer may not revoke US — that would let one compromised device sever the315    // whole mesh — so our own id is filtered out first.316    const newlyRevoked = await mergeDeviceRevocations(317      body.revoked.filter((r) => r.deviceId !== ourDeviceId),318    );319    for (const deviceId of newlyRevoked) {320      await removePairedDeviceById(deviceId);321      await removePendingVouchedDevice(deviceId);322      void recordSyncAlerts([323        {324          type: "DEVICE_REVOKED",325          entryId: "",326          entryTitle: deviceId,327          deviceName: issuer.deviceName ?? "paired device",328          timestamp: Date.now(),329        },330      ]);331    }332333    for (const entry of body.devices) {334      if (entry.deviceId === ourDeviceId || entry.deviceId === issuer.deviceId) {335        continue;336      }337      // Terminal: no manifest re-admits a revoked device. Matched on the key as338      // well as the id, because the id is the issuer's to choose — checking only339      // the id let a revoked key walk back in under a fresh one. The check sits340      // ahead of the existing-device lookup so it also refuses rotating a device341      // we still trust onto a revoked key.342      if (await isDeviceRevoked(entry.deviceId, entry.longTermPublicKeyHex)) {343        continue;344      }345      const existing = await findPairedDeviceById(entry.deviceId);346      const meshRoute = deriveManifestMeshRoute(347        masterKey,348        localKeys.publicKey,349        entry,350      );351352      // A v3 manifest from an admitted, KK-authenticated issuer proves353      // same-vault membership and carries enough route material for the two354      // introduced endpoints to derive their own capability. Admit it355      // immediately so a six-device vault converges without keeping the356      // original pairing hub online.357      if (!existing) {358        if (!meshRoute) continue;359        await upsertPairedDevice({360          deviceId: entry.deviceId,361          deviceName: entry.deviceName,362          deviceType: entry.deviceType,363          longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),364          signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),365          wsPort: entry.wsPort,366          rendezvousSecretHex: meshRoute.rendezvousSecretHex,367          relayUrl: meshRoute.relayUrl,368          pairedAt: entry.pairedAt,369          trustSource: "vouched",370        });371        await removePendingVouchedDevice(entry.deviceId);372        continue;373      }374375      // MV-8d: a key changing under a stable deviceId is legitimate after a376      // reinstall, but it is exactly what a graph-poisoning attack looks like —377      // signal the user either way, durably (the alert queue survives a closed378      // popup) and live (the broadcast updates an open one).379      if (380        existing.longTermPublicKeyHex &&381        !constantTimeEqualHex(382          existing.longTermPublicKeyHex,383          entry.longTermPublicKeyHex,384        )385      ) {386        // S5: name the device from the LOCAL record, never from the manifest.387        // The issuer is a third party here (its own entry is skipped above), so388        // `entry.deviceName` is an unverified claim about someone else — an389        // attacker who could put it on screen could make its own key rotation390        // read as a rotation on a device the user trusts more.391        const knownName = existing.deviceName ?? entry.deviceName;392        notifyPopup({393          type: "DEVICE_KEY_ROTATED",394          payload: { deviceName: knownName, deviceId: entry.deviceId },395        });396        void recordSyncAlerts([397          {398            type: "DEVICE_KEY_ROTATED",399            entryId: "",400            entryTitle: knownName,401            deviceName: knownName,402            timestamp: Date.now(),403          },404        ]);405      }406407      // Existing device — update in place as before. The name is deliberately408      // NOT taken from the manifest: a device's name is set by that device at409      // pairing, and letting a third-party issuer rewrite it is the rename-then-410      // impersonate half of S5. Self-renames never arrive here anyway.411      await upsertPairedDevice({412        ...existing,413        deviceId: entry.deviceId,414        deviceName: existing.deviceName ?? entry.deviceName,415        deviceType: entry.deviceType,416        longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),417        signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),418        pairedAt: existing.pairedAt ?? entry.pairedAt,419        trustSource: existing.trustSource ?? "direct",420        wsPort: existing.wsPort ?? entry.wsPort,421        rendezvousSecretHex:422          existing.trustSource === "vouched" && meshRoute423            ? meshRoute.rendezvousSecretHex424            : existing.rendezvousSecretHex,425        relayUrl:426          existing.trustSource === "vouched" && meshRoute427            ? meshRoute.relayUrl428            : existing.relayUrl,429        lastSyncedAt: existing.lastSyncedAt,430      });431    }432  } finally {433    masterKey.fill(0);434    localKeys.secretKey.fill(0);435  }436}437438function deriveManifestMeshRoute(439  masterKey: Uint8Array,440  localPublicKey: Uint8Array,441  entry: ManifestDeviceEntry,442): { rendezvousSecretHex: string; relayUrl: string } | null {443  try {444    if (!entry.relayUrl) return null;445    const relayUrl = normalizeRelayUrl(entry.relayUrl);446    const secret = deriveMeshRendezvousSecret(447      masterKey,448      localPublicKey,449      hexToPubkey(entry.longTermPublicKeyHex),450    );451    try {452      return {453        rendezvousSecretHex: rendezvousBytesToHex(secret),454        relayUrl,455      };456    } finally {457      secret.fill(0);458    }459  } catch {460    return null;461  }462}463464function notifyPopup(msg: { type: string; payload?: unknown }): void {465  try {466    void chrome.runtime.sendMessage(msg).catch(() => undefined);467  } catch {468    /* popup closed — the durable sync-alert queue remains authoritative */469  }470}471472function requireUnlocked(): void {473  if (!isUnlocked()) throw new VaultLockedError();474}475476// Sync derives everything — vault_id, the Noise static key, the Ed25519477// manifest signing key, and the per-entry envelope keys — from the vault's478// stable root key, NOT the password-derived key. This keeps paired devices'479// identities and envelope keys constant across a master-password change on480// either side (SEV-2-B); two paired devices with independently-rotated481// passwords still share this key and can decrypt each other's entries.482function requireMasterKey(): Uint8Array {483  if (!isUnlocked()) throw new VaultLockedError();484  const hex = getRootKeyHex();485  if (!hex) throw new VaultLockedError();486  return hexToBytes(hex);487}488489async function deriveEntryKey(masterKey: Uint8Array, entryId: string): Promise<CryptoKey> {490  // Null-byte separator (HKDF hardening): entryId cannot contain \x00, so this491  // makes the (entryId, suffix) boundary unambiguous regardless of future id492  // formats. Coordinated wire change — peach-android VaultSyncAdapter derives493  // the identical info; the two MUST stay byte-for-byte in lockstep.494  const info = new TextEncoder().encode(`${entryId}\x00${ENTRY_KEY_INFO_SUFFIX}`);495  const raw = new HKDF(SHA256, masterKey, new Uint8Array(0), info).expand(32);496  return crypto.subtle.importKey(497    "raw",498    raw.buffer as ArrayBuffer,499    { name: "AES-GCM" },500    false,501    ["encrypt", "decrypt"],502  );503}504505async function encryptEntry(key: CryptoKey, entry: VaultEntry): Promise<string> {506  const plaintext = new TextEncoder().encode(JSON.stringify(entry));507  const nonce = crypto.getRandomValues(new Uint8Array(12));508  const aad = new TextEncoder().encode(ENTRY_AAD);509  const ct = await crypto.subtle.encrypt(510    {511      name: "AES-GCM",512      iv: nonce.buffer as ArrayBuffer,513      additionalData: aad.buffer as ArrayBuffer,514      tagLength: 128,515    },516    key,517    plaintext.buffer as ArrayBuffer,518  );519  const ctBytes = new Uint8Array(ct);520  const envelope = new Uint8Array(nonce.length + ctBytes.length);521  envelope.set(nonce, 0);522  envelope.set(ctBytes, nonce.length);523  return bytesToBase64(envelope);524}525526async function decryptEntryOrNull(key: CryptoKey, envelopeB64: string): Promise<VaultEntry | null> {527  try {528    const bytes = base64ToBytes(envelopeB64);529    if (bytes.length < 12 + 16) return null;530    const nonce = bytes.subarray(0, 12);531    const ct = bytes.subarray(12);532    const aad = new TextEncoder().encode(ENTRY_AAD);533    const pt = await crypto.subtle.decrypt(534      {535        name: "AES-GCM",536        iv: nonce.buffer.slice(nonce.byteOffset, nonce.byteOffset + nonce.byteLength) as ArrayBuffer,537        additionalData: aad.buffer as ArrayBuffer,538        tagLength: 128,539      },540      key,541      ct.buffer.slice(ct.byteOffset, ct.byteOffset + ct.byteLength) as ArrayBuffer,542    );543    const json = new TextDecoder().decode(pt);544    const parsed = JSON.parse(json);545    if (!parsed || typeof parsed !== "object" || typeof parsed.id !== "string") return null;546    return parsed as VaultEntry;547  } catch {548    return null;549  }550}551552function hexToBytes(hex: string): Uint8Array {553  if (hex.length % 2 !== 0) throw new Error("hex length must be even");554  const out = new Uint8Array(hex.length / 2);555  for (let i = 0; i < out.length; i++) {556    out[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);557  }558  return out;559}560561function bytesToBase64(bytes: Uint8Array): string {562  let bin = "";563  for (let i = 0; i < bytes.length; i++) bin += String.fromCharCode(bytes[i]);564  return btoa(bin);565}566567function base64ToBytes(b64: string): Uint8Array {568  const bin = atob(b64);569  const out = new Uint8Array(bin.length);570  for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i);571  return out;572}