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}$/.test(device.signingPublicKeyHex)244  ) {245    return null;246  }247  return {248    deviceId: device.deviceId,249    deviceName: device.deviceName,250    deviceType: device.deviceType,251    longTermPublicKeyHex: device.longTermPublicKeyHex,252    signingPublicKeyHex: device.signingPublicKeyHex,253    wsPort: device.wsPort,254    relayUrl: device.relayUrl,255    pairedAt: device.pairedAt,256  };257}258259/**260 * Apply a device manifest issued by a peer we pair with directly.261 *262 * The issuer used to be required to be an "extension", on the assumption that263 * the extension was the mesh's trust anchor. It is not: the device a fresh264 * install joins through is the one holding the peer list to hand over.265 *266 * The issuer must already be admitted locally as either direct or vouched.267 * That is the decentralisation boundary: an unknown key has no session and no268 * authority, while every authenticated member can propagate the same signed269 * pool without the original hub online. A v3 entry is admitted only when it270 * carries a valid relay route; both endpoints independently derive the same271 * pair-only capability from their vault root and public keys.272 */273async function applyVerifiedPeerManifest(274  manifest: SignedDeviceManifest,275  authenticatedRemoteStaticPublicKey: Uint8Array,276): Promise<void> {277  const issuerId = manifest?.body?.issuerDeviceId;278  if (typeof issuerId !== "string" || !issuerId) { return; }279280  if (authenticatedRemoteStaticPublicKey.length !== 32) {281    return;282  }283  const authenticatedPubkeyHex = pubkeyToHex(authenticatedRemoteStaticPublicKey);284  const issuer = await findPairedDeviceByPubkey(authenticatedPubkeyHex);285  if (286    !issuer ||287    issuer.deviceId !== issuerId ||288    (289      issuer.trustSource !== "direct" &&290      issuer.trustSource !== "vouched"291    ) ||292    !issuer.signingPublicKeyHex ||293    !/^[0-9a-f]{64}$/.test(issuer.signingPublicKeyHex)294  ) {295    return;296  }297298  let body: Awaited<ReturnType<typeof verifyDeviceManifest>>;299  try {300    body = await verifyDeviceManifest(301      manifest,302      hexToPubkey(issuer!.signingPublicKeyHex!),303    );304  } catch (storedError) {305    // Stored key may be stale (older builds persisted the key derived at306    // first-pair and never refreshed it). The signing keypair is deterministic307    // from (masterKey, deviceId) on both sides, so retry once with the locally308    // re-derived pubkey. A genuinely forged signature throws here and is309    // silently rejected — only a stale-but-correct key survives the retry.310    const masterForIssuer = requireMasterKey();311    try {312      const derived = await deriveSyncSigningKeypair(313        masterForIssuer,314        issuer.deviceId,315      );316      body = await verifyDeviceManifest(manifest, derived.publicKeyRaw);317    } catch (derivedError) {318      return;319    } finally {320      masterForIssuer.fill(0);321    }322  }323  if (body.issuerDeviceId !== issuer.deviceId) { return; }324325  const ourDeviceId = await getOrCreateDeviceId();326  const masterKey = requireMasterKey();327  const localKeys = deriveSyncIdentityKeypair(masterKey, ourDeviceId);328329  try {330    // Revocations are absorbed BEFORE any vouching, so a manifest that both331    // revokes and re-vouches the same device in one payload cannot race itself.332    // A peer may not revoke US — that would let one compromised device sever the333    // whole mesh — so our own id is filtered out first.334    const newlyRevoked = await mergeDeviceRevocations(335      body.revoked.filter((r) => r.deviceId !== ourDeviceId),336    );337    for (const deviceId of newlyRevoked) {338      await removePairedDeviceById(deviceId);339      await removePendingVouchedDevice(deviceId);340      void recordSyncAlerts([341        {342          type: "DEVICE_REVOKED",343          entryId: "",344          entryTitle: deviceId,345          deviceName: issuer.deviceName ?? "paired device",346          timestamp: Date.now(),347        },348      ]);349    }350351    for (const entry of body.devices) {352      if (entry.deviceId === ourDeviceId || entry.deviceId === issuer.deviceId) {353        continue;354      }355      // Terminal: no manifest re-admits a revoked device. Matched on the key as356      // well as the id, because the id is the issuer's to choose — checking only357      // the id let a revoked key walk back in under a fresh one. The check sits358      // ahead of the existing-device lookup so it also refuses rotating a device359      // we still trust onto a revoked key.360      if (await isDeviceRevoked(entry.deviceId, entry.longTermPublicKeyHex)) {361        continue;362      }363      const existing = await findPairedDeviceById(entry.deviceId);364      const meshRoute = deriveManifestMeshRoute(365        masterKey,366        localKeys.publicKey,367        entry,368      );369      if (existing) {370      } else if (!meshRoute) {371      } else {372      }373374      // A v3 manifest from an admitted, KK-authenticated issuer proves375      // same-vault membership and carries enough route material for the two376      // introduced endpoints to derive their own capability. Admit it377      // immediately so a six-device vault converges without keeping the378      // original pairing hub online.379      if (!existing) {380        if (!meshRoute) continue;381        await upsertPairedDevice({382          deviceId: entry.deviceId,383          deviceName: entry.deviceName,384          deviceType: entry.deviceType,385          longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),386          signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),387          wsPort: entry.wsPort,388          rendezvousSecretHex: meshRoute.rendezvousSecretHex,389          relayUrl: meshRoute.relayUrl,390          pairedAt: entry.pairedAt,391          trustSource: "vouched",392        });393        await removePendingVouchedDevice(entry.deviceId);394        continue;395      }396397      // MV-8d: a key changing under a stable deviceId is legitimate after a398      // reinstall, but it is exactly what a graph-poisoning attack looks like —399      // signal the user either way, durably (the alert queue survives a closed400      // popup) and live (the broadcast updates an open one).401      if (402        existing.longTermPublicKeyHex &&403        !constantTimeEqualHex(404          existing.longTermPublicKeyHex,405          entry.longTermPublicKeyHex,406        )407      ) {408        // S5: name the device from the LOCAL record, never from the manifest.409        // The issuer is a third party here (its own entry is skipped above), so410        // `entry.deviceName` is an unverified claim about someone else — an411        // attacker who could put it on screen could make its own key rotation412        // read as a rotation on a device the user trusts more.413        const knownName = existing.deviceName ?? entry.deviceName;414        notifyPopup({415          type: "DEVICE_KEY_ROTATED",416          payload: { deviceName: knownName, deviceId: entry.deviceId },417        });418        void recordSyncAlerts([419          {420            type: "DEVICE_KEY_ROTATED",421            entryId: "",422            entryTitle: knownName,423            deviceName: knownName,424            timestamp: Date.now(),425          },426        ]);427      }428429      // Existing device — update in place as before. The name is deliberately430      // NOT taken from the manifest: a device's name is set by that device at431      // pairing, and letting a third-party issuer rewrite it is the rename-then-432      // impersonate half of S5. Self-renames never arrive here anyway.433      await upsertPairedDevice({434        ...existing,435        deviceId: entry.deviceId,436        deviceName: existing.deviceName ?? entry.deviceName,437        deviceType: entry.deviceType,438        longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),439        signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),440        pairedAt: existing.pairedAt ?? entry.pairedAt,441        trustSource: existing.trustSource ?? "direct",442        wsPort: existing.wsPort ?? entry.wsPort,443        rendezvousSecretHex:444          existing.trustSource === "vouched" && meshRoute445            ? meshRoute.rendezvousSecretHex446            : existing.rendezvousSecretHex,447        relayUrl:448          existing.trustSource === "vouched" && meshRoute449            ? meshRoute.relayUrl450            : existing.relayUrl,451        lastSyncedAt: existing.lastSyncedAt,452      });453    }454  } finally {455    masterKey.fill(0);456    localKeys.secretKey.fill(0);457  }458}459460function deriveManifestMeshRoute(461  masterKey: Uint8Array,462  localPublicKey: Uint8Array,463  entry: ManifestDeviceEntry,464): { rendezvousSecretHex: string; relayUrl: string } | null {465  try {466    if (!entry.relayUrl) return null;467    const relayUrl = normalizeRelayUrl(entry.relayUrl);468    const secret = deriveMeshRendezvousSecret(469      masterKey,470      localPublicKey,471      hexToPubkey(entry.longTermPublicKeyHex),472    );473    try {474      return {475        rendezvousSecretHex: rendezvousBytesToHex(secret),476        relayUrl,477      };478    } finally {479      secret.fill(0);480    }481  } catch {482    return null;483  }484}485486function notifyPopup(msg: { type: string; payload?: unknown }): void {487  try {488    void chrome.runtime.sendMessage(msg).catch(() => undefined);489  } catch {490    /* popup closed — the durable sync-alert queue remains authoritative */491  }492}493494function requireUnlocked(): void {495  if (!isUnlocked()) throw new VaultLockedError();496}497498// Sync derives everything — vault_id, the Noise static key, the Ed25519499// manifest signing key, and the per-entry envelope keys — from the vault's500// stable root key, NOT the password-derived key. This keeps paired devices'501// identities and envelope keys constant across a master-password change on502// either side (SEV-2-B); two paired devices with independently-rotated503// passwords still share this key and can decrypt each other's entries.504function requireMasterKey(): Uint8Array {505  if (!isUnlocked()) throw new VaultLockedError();506  const hex = getRootKeyHex();507  if (!hex) throw new VaultLockedError();508  return hexToBytes(hex);509}510511async function deriveEntryKey(masterKey: Uint8Array, entryId: string): Promise<CryptoKey> {512  // Null-byte separator (HKDF hardening): entryId cannot contain \x00, so this513  // makes the (entryId, suffix) boundary unambiguous regardless of future id514  // formats. Coordinated wire change — peach-android VaultSyncAdapter derives515  // the identical info; the two MUST stay byte-for-byte in lockstep.516  const info = new TextEncoder().encode(`${entryId}\x00${ENTRY_KEY_INFO_SUFFIX}`);517  const raw = new HKDF(SHA256, masterKey, new Uint8Array(0), info).expand(32);518  return crypto.subtle.importKey(519    "raw",520    raw.buffer as ArrayBuffer,521    { name: "AES-GCM" },522    false,523    ["encrypt", "decrypt"],524  );525}526527async function encryptEntry(key: CryptoKey, entry: VaultEntry): Promise<string> {528  const plaintext = new TextEncoder().encode(JSON.stringify(entry));529  const nonce = crypto.getRandomValues(new Uint8Array(12));530  const aad = new TextEncoder().encode(ENTRY_AAD);531  const ct = await crypto.subtle.encrypt(532    {533      name: "AES-GCM",534      iv: nonce.buffer as ArrayBuffer,535      additionalData: aad.buffer as ArrayBuffer,536      tagLength: 128,537    },538    key,539    plaintext.buffer as ArrayBuffer,540  );541  const ctBytes = new Uint8Array(ct);542  const envelope = new Uint8Array(nonce.length + ctBytes.length);543  envelope.set(nonce, 0);544  envelope.set(ctBytes, nonce.length);545  return bytesToBase64(envelope);546}547548async function decryptEntryOrNull(key: CryptoKey, envelopeB64: string): Promise<VaultEntry | null> {549  try {550    const bytes = base64ToBytes(envelopeB64);551    if (bytes.length < 12 + 16) return null;552    const nonce = bytes.subarray(0, 12);553    const ct = bytes.subarray(12);554    const aad = new TextEncoder().encode(ENTRY_AAD);555    const pt = await crypto.subtle.decrypt(556      {557        name: "AES-GCM",558        iv: nonce.buffer.slice(nonce.byteOffset, nonce.byteOffset + nonce.byteLength) as ArrayBuffer,559        additionalData: aad.buffer as ArrayBuffer,560        tagLength: 128,561      },562      key,563      ct.buffer.slice(ct.byteOffset, ct.byteOffset + ct.byteLength) as ArrayBuffer,564    );565    const json = new TextDecoder().decode(pt);566    const parsed = JSON.parse(json);567    if (!parsed || typeof parsed !== "object" || typeof parsed.id !== "string") return null;568    return parsed as VaultEntry;569  } catch {570    return null;571  }572}573574function hexToBytes(hex: string): Uint8Array {575  if (hex.length % 2 !== 0) throw new Error("hex length must be even");576  const out = new Uint8Array(hex.length / 2);577  for (let i = 0; i < out.length; i++) {578    out[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);579  }580  return out;581}582583function bytesToBase64(bytes: Uint8Array): string {584  let bin = "";585  for (let i = 0; i < bytes.length; i++) bin += String.fromCharCode(bytes[i]);586  return btoa(bin);587}588589function base64ToBytes(b64: string): Uint8Array {590  const bin = atob(b64);591  const out = new Uint8Array(bin.length);592  for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i);593  return out;594}