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    // Stored key may be stale (older builds persisted the key derived at304    // first-pair and never refreshed it). The signing keypair is deterministic305    // from (masterKey, deviceId) on both sides, so retry once with the locally306    // re-derived pubkey. A genuinely forged signature throws here and is307    // silently rejected — only a stale-but-correct key survives the retry.308    const masterForIssuer = requireMasterKey();309    try {310      const derived = await deriveSyncSigningKeypair(311        masterForIssuer,312        issuer.deviceId,313      );314      body = await verifyDeviceManifest(manifest, derived.publicKeyRaw);315    } catch {316      return;317    } finally {318      masterForIssuer.fill(0);319    }320  }321  if (body.issuerDeviceId !== issuer.deviceId) return;322323  const ourDeviceId = await getOrCreateDeviceId();324  const masterKey = requireMasterKey();325  const localKeys = deriveSyncIdentityKeypair(masterKey, ourDeviceId);326327  try {328    // Revocations are absorbed BEFORE any vouching, so a manifest that both329    // revokes and re-vouches the same device in one payload cannot race itself.330    // A peer may not revoke US — that would let one compromised device sever the331    // whole mesh — so our own id is filtered out first.332    const newlyRevoked = await mergeDeviceRevocations(333      body.revoked.filter((r) => r.deviceId !== ourDeviceId),334    );335    for (const deviceId of newlyRevoked) {336      await removePairedDeviceById(deviceId);337      await removePendingVouchedDevice(deviceId);338      void recordSyncAlerts([339        {340          type: "DEVICE_REVOKED",341          entryId: "",342          entryTitle: deviceId,343          deviceName: issuer.deviceName ?? "paired device",344          timestamp: Date.now(),345        },346      ]);347    }348349    for (const entry of body.devices) {350      if (entry.deviceId === ourDeviceId || entry.deviceId === issuer.deviceId) {351        continue;352      }353      // Terminal: no manifest re-admits a revoked device. Matched on the key as354      // well as the id, because the id is the issuer's to choose — checking only355      // the id let a revoked key walk back in under a fresh one. The check sits356      // ahead of the existing-device lookup so it also refuses rotating a device357      // we still trust onto a revoked key.358      if (await isDeviceRevoked(entry.deviceId, entry.longTermPublicKeyHex)) {359        continue;360      }361      const existing = await findPairedDeviceById(entry.deviceId);362      const meshRoute = deriveManifestMeshRoute(363        masterKey,364        localKeys.publicKey,365        entry,366      );367368      // A v3 manifest from an admitted, KK-authenticated issuer proves369      // same-vault membership and carries enough route material for the two370      // introduced endpoints to derive their own capability. Admit it371      // immediately so a six-device vault converges without keeping the372      // original pairing hub online.373      if (!existing) {374        if (!meshRoute) continue;375        await upsertPairedDevice({376          deviceId: entry.deviceId,377          deviceName: entry.deviceName,378          deviceType: entry.deviceType,379          longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),380          signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),381          wsPort: entry.wsPort,382          rendezvousSecretHex: meshRoute.rendezvousSecretHex,383          relayUrl: meshRoute.relayUrl,384          pairedAt: entry.pairedAt,385          trustSource: "vouched",386        });387        await removePendingVouchedDevice(entry.deviceId);388        continue;389      }390391      // MV-8d: a key changing under a stable deviceId is legitimate after a392      // reinstall, but it is exactly what a graph-poisoning attack looks like —393      // signal the user either way, durably (the alert queue survives a closed394      // popup) and live (the broadcast updates an open one).395      if (396        existing.longTermPublicKeyHex &&397        !constantTimeEqualHex(398          existing.longTermPublicKeyHex,399          entry.longTermPublicKeyHex,400        )401      ) {402        // S5: name the device from the LOCAL record, never from the manifest.403        // The issuer is a third party here (its own entry is skipped above), so404        // `entry.deviceName` is an unverified claim about someone else — an405        // attacker who could put it on screen could make its own key rotation406        // read as a rotation on a device the user trusts more.407        const knownName = existing.deviceName ?? entry.deviceName;408        notifyPopup({409          type: "DEVICE_KEY_ROTATED",410          payload: { deviceName: knownName, deviceId: entry.deviceId },411        });412        void recordSyncAlerts([413          {414            type: "DEVICE_KEY_ROTATED",415            entryId: "",416            entryTitle: knownName,417            deviceName: knownName,418            timestamp: Date.now(),419          },420        ]);421      }422423      // Existing device — update in place as before. The name is deliberately424      // NOT taken from the manifest: a device's name is set by that device at425      // pairing, and letting a third-party issuer rewrite it is the rename-then-426      // impersonate half of S5. Self-renames never arrive here anyway.427      await upsertPairedDevice({428        ...existing,429        deviceId: entry.deviceId,430        deviceName: existing.deviceName ?? entry.deviceName,431        deviceType: entry.deviceType,432        longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),433        signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),434        pairedAt: existing.pairedAt ?? entry.pairedAt,435        trustSource: existing.trustSource ?? "direct",436        wsPort: existing.wsPort ?? entry.wsPort,437        rendezvousSecretHex:438          existing.trustSource === "vouched" && meshRoute439            ? meshRoute.rendezvousSecretHex440            : existing.rendezvousSecretHex,441        relayUrl:442          existing.trustSource === "vouched" && meshRoute443            ? meshRoute.relayUrl444            : existing.relayUrl,445        lastSyncedAt: existing.lastSyncedAt,446      });447    }448  } finally {449    masterKey.fill(0);450    localKeys.secretKey.fill(0);451  }452}453454function deriveManifestMeshRoute(455  masterKey: Uint8Array,456  localPublicKey: Uint8Array,457  entry: ManifestDeviceEntry,458): { rendezvousSecretHex: string; relayUrl: string } | null {459  try {460    if (!entry.relayUrl) return null;461    const relayUrl = normalizeRelayUrl(entry.relayUrl);462    const secret = deriveMeshRendezvousSecret(463      masterKey,464      localPublicKey,465      hexToPubkey(entry.longTermPublicKeyHex),466    );467    try {468      return {469        rendezvousSecretHex: rendezvousBytesToHex(secret),470        relayUrl,471      };472    } finally {473      secret.fill(0);474    }475  } catch {476    return null;477  }478}479480function notifyPopup(msg: { type: string; payload?: unknown }): void {481  try {482    void chrome.runtime.sendMessage(msg).catch(() => undefined);483  } catch {484    /* popup closed — the durable sync-alert queue remains authoritative */485  }486}487488function requireUnlocked(): void {489  if (!isUnlocked()) throw new VaultLockedError();490}491492// Sync derives everything — vault_id, the Noise static key, the Ed25519493// manifest signing key, and the per-entry envelope keys — from the vault's494// stable root key, NOT the password-derived key. This keeps paired devices'495// identities and envelope keys constant across a master-password change on496// either side (SEV-2-B); two paired devices with independently-rotated497// passwords still share this key and can decrypt each other's entries.498function requireMasterKey(): Uint8Array {499  if (!isUnlocked()) throw new VaultLockedError();500  const hex = getRootKeyHex();501  if (!hex) throw new VaultLockedError();502  return hexToBytes(hex);503}504505async function deriveEntryKey(masterKey: Uint8Array, entryId: string): Promise<CryptoKey> {506  // Null-byte separator (HKDF hardening): entryId cannot contain \x00, so this507  // makes the (entryId, suffix) boundary unambiguous regardless of future id508  // formats. Coordinated wire change — peach-android VaultSyncAdapter derives509  // the identical info; the two MUST stay byte-for-byte in lockstep.510  const info = new TextEncoder().encode(`${entryId}\x00${ENTRY_KEY_INFO_SUFFIX}`);511  const raw = new HKDF(SHA256, masterKey, new Uint8Array(0), info).expand(32);512  return crypto.subtle.importKey(513    "raw",514    raw.buffer as ArrayBuffer,515    { name: "AES-GCM" },516    false,517    ["encrypt", "decrypt"],518  );519}520521async function encryptEntry(key: CryptoKey, entry: VaultEntry): Promise<string> {522  const plaintext = new TextEncoder().encode(JSON.stringify(entry));523  const nonce = crypto.getRandomValues(new Uint8Array(12));524  const aad = new TextEncoder().encode(ENTRY_AAD);525  const ct = await crypto.subtle.encrypt(526    {527      name: "AES-GCM",528      iv: nonce.buffer as ArrayBuffer,529      additionalData: aad.buffer as ArrayBuffer,530      tagLength: 128,531    },532    key,533    plaintext.buffer as ArrayBuffer,534  );535  const ctBytes = new Uint8Array(ct);536  const envelope = new Uint8Array(nonce.length + ctBytes.length);537  envelope.set(nonce, 0);538  envelope.set(ctBytes, nonce.length);539  return bytesToBase64(envelope);540}541542async function decryptEntryOrNull(key: CryptoKey, envelopeB64: string): Promise<VaultEntry | null> {543  try {544    const bytes = base64ToBytes(envelopeB64);545    if (bytes.length < 12 + 16) return null;546    const nonce = bytes.subarray(0, 12);547    const ct = bytes.subarray(12);548    const aad = new TextEncoder().encode(ENTRY_AAD);549    const pt = await crypto.subtle.decrypt(550      {551        name: "AES-GCM",552        iv: nonce.buffer.slice(nonce.byteOffset, nonce.byteOffset + nonce.byteLength) as ArrayBuffer,553        additionalData: aad.buffer as ArrayBuffer,554        tagLength: 128,555      },556      key,557      ct.buffer.slice(ct.byteOffset, ct.byteOffset + ct.byteLength) as ArrayBuffer,558    );559    const json = new TextDecoder().decode(pt);560    const parsed = JSON.parse(json);561    if (!parsed || typeof parsed !== "object" || typeof parsed.id !== "string") return null;562    return parsed as VaultEntry;563  } catch {564    return null;565  }566}567568function hexToBytes(hex: string): Uint8Array {569  if (hex.length % 2 !== 0) throw new Error("hex length must be even");570  const out = new Uint8Array(hex.length / 2);571  for (let i = 0; i < out.length; i++) {572    out[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);573  }574  return out;575}576577function bytesToBase64(bytes: Uint8Array): string {578  let bin = "";579  for (let i = 0; i < bytes.length; i++) bin += String.fromCharCode(bytes[i]);580  return btoa(bin);581}582583function base64ToBytes(b64: string): Uint8Array {584  const bin = atob(b64);585  const out = new Uint8Array(bin.length);586  for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i);587  return out;588}