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 { DeviceManifestBody, DeviceRevocation } from "../shared/sync-types";28import type { SyncVaultAdapter } from "./sync-coordinator";29import { getDeviceName, getLocalPairingIdentity, getOrCreateDeviceId } from "./device-identity";30import {31  computeVaultId,32  hexToPubkey,33  pubkeyToHex,34} from "../shared/sync-identity";35import {36  buildSignedDeviceManifest,37  signDeviceRevocation,38  verifyDeviceManifest,39  verifyDeviceRevocation,40} from "../shared/device-manifest";41import { constantTimeEqualHex } from "../shared/constant-time";42import {43  applyMergedRemoteEntries,44  getTombstoneManifest,45  getRootKeyHex,46  getEntries,47  getEntryById,48  getVaultVersion,49  isUnlocked,50  isDecoyMode,51} from "./vault";52import {53  findPairedDeviceById,54  findPairedDeviceByPubkey,55  isDeviceRevoked,56  listDeviceRevocations,57  listPairedDevices,58  upsertPairedDevicesAndMergeRevocations,59} from "./paired-devices";60import { setPairSecret } from "./pair-secrets";61import {62  removePendingVouchedDevice,63} from "./pending-vouched-devices";64import {65  bytesToHex as rendezvousBytesToHex,66  deriveMeshRendezvousSecret,67  normalizeRelayUrl,68} from "../shared/rendezvous";69import { recordSyncAlerts } from "./sync-alerts";70import { SYNC_LIMITS, clampSyncTimestamp } from "../shared/sync-limits";71import type { VaultEntry } from "../shared/types";72import {73  MAX_VOUCH_DEPTH,74  type ManifestDeviceEntry,75  type PairedDevice,76  type SignedDeviceManifest,77} from "../shared/sync-types";78import { replaceLockedSyncSpool, drainLockedSyncInbox } from "./locked-sync-spool";7980// Each entry uses a unique AES-GCM key: HKDF(masterKey, info = entryId + "\x00" + "sync-entry-v1").81// The info binding prevents a ciphertext from one entry slot being replayed into another.82const ENTRY_KEY_INFO_SUFFIX = "sync-entry-v1";83const ENTRY_AAD = "peach-sync-entry-v1";8485export class VaultLockedError extends Error {86  constructor() {87    super("vault_locked");88    this.name = "VaultLockedError";89  }90}9192export function createSyncVaultAdapter(93  _context: { deviceName?: string } = {},94): SyncVaultAdapter {95  return {96    async computeVaultId() {97      const master = requireMasterKey();98      return computeVaultId(master);99    },100101    async getOurDeviceId() {102      return getOrCreateDeviceId();103    },104105    async getLocalVersion() {106      return getVaultVersion();107    },108109    async buildEntryManifest() {110      requireRealUnlocked();111      const manifest: Record<string, number> = {};112      for (const entry of getEntries()) {113        manifest[entry.id] = entry.modifiedAt;114      }115      return manifest;116    },117118    async buildTombstoneManifest() {119      requireRealUnlocked();120      return getTombstoneManifest();121    },122123    async getEncryptedEntries(entryIds) {124      requireRealUnlocked();125      const masterKey = requireMasterKey();126      const out: Record<string, string> = {};127      for (const id of entryIds) {128        const entry = getEntryById(id);129        if (!entry) continue;130        const key = await deriveEntryKey(masterKey, id);131        out[id] = await encryptEntry(key, entry);132      }133      return out;134    },135136    async applyEntries(entries) {137      requireRealUnlocked();138      const entryList = Object.entries(entries);139      if (entryList.length > SYNC_LIMITS.MAX_ENTRY_COUNT) {140        throw new Error(141          `sync entry count ${entryList.length} exceeds limit ${SYNC_LIMITS.MAX_ENTRY_COUNT}`,142        );143      }144      const masterKey = requireMasterKey();145      const decrypted: VaultEntry[] = [];146      for (const [id, envelope] of entryList) {147        if (envelope.length > (SYNC_LIMITS.MAX_ENTRY_PLAINTEXT_BYTES * 4) / 3 + 64) continue;148        const key = await deriveEntryKey(masterKey, id);149        const entry = await decryptEntryOrNull(key, envelope);150        if (!entry) continue;151        if (JSON.stringify(entry).length > SYNC_LIMITS.MAX_ENTRY_PLAINTEXT_BYTES) continue;152        if (entry.id !== id) continue;153        decrypted.push(entry);154      }155      if (decrypted.length > 0) {156        requireRealUnlocked();157        await applyMergedRemoteEntries(decrypted, {});158      }159    },160161    async applyTombstones(tombstones) {162      requireRealUnlocked();163      const tombstoneList = Object.entries(tombstones);164      if (tombstoneList.length > SYNC_LIMITS.MAX_TOMBSTONE_COUNT) {165        throw new Error(166          `sync tombstone count ${tombstoneList.length} exceeds limit ${SYNC_LIMITS.MAX_TOMBSTONE_COUNT}`,167        );168      }169      const cleaned: Record<string, number> = {};170      for (const [id, ts] of tombstoneList) {171        if (typeof ts === "number" && Number.isFinite(ts) && ts > 0) {172          cleaned[id] = clampSyncTimestamp(ts);173        }174      }175      if (Object.keys(cleaned).length > 0) {176        requireRealUnlocked();177        await applyMergedRemoteEntries([], cleaned);178      }179    },180181    async buildOutgoingDeviceManifest() {182      requireRealUnlocked();183      const local = await getLocalPairingIdentity();184      try {185        const issuerDeviceId = local.identity.deviceId;186        const revoked = await listDeviceRevocations();187        const revokedIds = new Set(revoked.map((r) => r.deviceId));188        const devices = (await listPairedDevices())189          .filter((d) => !revokedIds.has(d.deviceId))190          .map(toManifestEntry)191          .filter((d): d is ManifestDeviceEntry => d !== null);192        const signedRevoked = (193          await Promise.all(revoked.map(async (record) => {194            // A terminal record may have been issued by another mesh member.195            // Preserve its signature unchanged after checking that issuer's196            // current or immutable historical signing key is trusted locally.197            if (198              record.signatureHex &&199              record.issuerSigningPublicKeyHex &&200              record.issuerSigningKeyVersion201            ) {202              const issuer = await findPairedDeviceById(record.revokedByDeviceId);203              const trustedKeys = [204                ...(issuer?.signingKeyHistory ?? []),205                ...(issuer?.signingPublicKeyHex206                  ? [{ version: issuer.signingKeyHistory?.length207                    ? Math.max(...issuer.signingKeyHistory.map((key) => key.version)) + 1208                    : 1, publicKeyHex: issuer.signingPublicKeyHex }]209                  : []),210              ];211              for (const key of trustedKeys) {212                if (213                  key.version === record.issuerSigningKeyVersion &&214                  key.publicKeyHex.toLowerCase() === record.issuerSigningPublicKeyHex.toLowerCase() &&215                  await verifyDeviceRevocation(record, hexToPubkey(key.publicKeyHex))216                ) return record;217              }218              return null;219            }220            // Only this device may mint a new signature; never re-issue a221            // record attributed to a different issuer as our own.222            if (record.revokedByDeviceId !== issuerDeviceId) return null;223            return signDeviceRevocation(224              record,225              local.signingPrivateKey,226              local.identity.signingPublicKeyHex!,227            );228          }))229        ).filter((record): record is DeviceRevocation => record !== null);230        return buildSignedDeviceManifest(231          issuerDeviceId,232          devices,233          local.signingPrivateKey,234          { revoked: signedRevoked },235        );236      } finally {237        local.privateKey.fill(0);238        local.publicKey.fill(0);239      }240    },241242    async applyIncomingDeviceManifest(manifest, authenticatedRemoteStaticPublicKey) {243      requireRealUnlocked();244      await applyVerifiedPeerManifest(245        manifest,246        authenticatedRemoteStaticPublicKey,247      );248    },249  };250}251252export async function refreshLockedSyncSpool(): Promise<void> {253  requireUnlocked();254  const masterKey = requireMasterKey();255  const deviceId = await getOrCreateDeviceId();256  const identity = await buildCachedIdentity(masterKey, deviceId);257  const cachedEntries: Record<string, { modifiedAt: number; ciphertext: string }> = {};258  try {259    for (const entry of getEntries()) {260      if (entry.deletedAt) continue;261      const key = await deriveEntryKey(masterKey, entry.id);262      cachedEntries[entry.id] = {263        modifiedAt: entry.modifiedAt,264        ciphertext: await encryptEntry(key, entry),265      };266    }267    const tombstones = getTombstoneManifest();268    // PB-26-104: the private key rides along because locked sync needs it, but269    // the spool is written to chrome.storage.session — never to disk. See270    // locked-sync-spool.ts for why session storage is the only home that271    // satisfies both constraints.272    const { longTermPrivateKeyBytes: _privateKeyBytes, ...storedIdentity } = identity;273    await replaceLockedSyncSpool({274      ...storedIdentity,275      localVersion: await getVaultVersion(),276      entries: cachedEntries,277      tombstones,278    });279  } finally {280    masterKey.fill(0);281    identity.longTermPrivateKeyBytes.fill(0);282  }283}284285export async function drainAndRefreshLockedSyncSpool(): Promise<void> {286  const live = createSyncVaultAdapter();287  await drainLockedSyncInbox(live);288  await refreshLockedSyncSpool();289}290291async function buildCachedIdentity(masterKey: Uint8Array, _deviceId: string) {292  const vaultId = await computeVaultId(masterKey);293  const pairing = await getLocalPairingIdentity();294  const deviceName = await getDeviceName();295  return {296    vaultId,297    deviceId: pairing.identity.deviceId,298    deviceName,299    deviceType: "extension" as const,300    longTermPublicKeyHex: pubkeyToHex(pairing.publicKey),301    longTermPrivateKeyHex: bytesToHex(pairing.privateKey),302    longTermPrivateKeyBytes: pairing.privateKey,303  };304}305306function toManifestEntry(device: PairedDevice): ManifestDeviceEntry | null {307  if (308    !device.deviceId ||309    !device.deviceName ||310    !device.deviceType ||311    !device.longTermPublicKeyHex ||312    !/^[0-9a-f]{64}$/.test(device.longTermPublicKeyHex) ||313    !device.signingPublicKeyHex ||314    !/^[0-9a-f]{64}$/.test(device.signingPublicKeyHex)315  ) {316    return null;317  }318  return {319    deviceId: device.deviceId,320    deviceName: device.deviceName,321    deviceType: device.deviceType,322    longTermPublicKeyHex: device.longTermPublicKeyHex,323    signingPublicKeyHex: device.signingPublicKeyHex,324    wsPort: device.wsPort,325    relayUrl: device.relayUrl,326    pairedAt: device.pairedAt,327    vouchDepth: device.vouchDepth ?? 0,328  };329}330331/**332 * Apply a device manifest issued by a peer we pair with directly.333 *334 * The issuer used to be required to be an "extension", on the assumption that335 * the extension was the mesh's trust anchor. It is not: the device a fresh336 * install joins through is the one holding the peer list to hand over.337 *338 * The issuer must already be admitted locally as either direct or vouched.339 * That is the decentralisation boundary: an unknown key has no session and no340 * authority, while every authenticated member can propagate the same signed341 * pool without the original hub online. A v3 entry is admitted only when it342 * carries a valid relay route; both endpoints independently derive the same343 * pair-only capability from their vault root and public keys.344 */345async function applyVerifiedPeerManifest(346  manifest: SignedDeviceManifest,347  authenticatedRemoteStaticPublicKey: Uint8Array,348): Promise<void> {349  const issuerId = manifest?.body?.issuerDeviceId;350  if (typeof issuerId !== "string" || !issuerId) { return; }351352  if (authenticatedRemoteStaticPublicKey.length !== 32) {353    return;354  }355  const authenticatedPubkeyHex = pubkeyToHex(authenticatedRemoteStaticPublicKey);356  const issuer = await findPairedDeviceByPubkey(authenticatedPubkeyHex);357  if (358    !issuer ||359    issuer.deviceId !== issuerId ||360    (361      issuer.trustSource !== "direct" &&362      issuer.trustSource !== "vouched"363    ) ||364    (issuer.vouchDepth ?? 0) >= MAX_VOUCH_DEPTH ||365    !issuer.signingPublicKeyHex ||366    !/^[0-9a-f]{64}$/.test(issuer.signingPublicKeyHex)367  ) {368    return;369  }370371  let body: DeviceManifestBody | undefined;372  let selectedSigningKey: { version: number; publicKeyHex: string } | undefined;373  const issuerSigningPublicKeyHex = issuer.signingPublicKeyHex;374  const historicalKeys = (issuer.signingKeyHistory ?? [])375    .filter((key) => Number.isInteger(key.version) && key.version > 0 && /^[0-9a-f]{64}$/i.test(key.publicKeyHex))376    .map((key) => ({ version: key.version, publicKeyHex: key.publicKeyHex.toLowerCase() }));377  const currentVersion = historicalKeys.find(378    (key) => key.publicKeyHex === issuerSigningPublicKeyHex.toLowerCase(),379  )?.version ?? (historicalKeys.reduce((max, key) => Math.max(max, key.version), 0) + 1);380  const signingKeys = [381    ...historicalKeys,382    { version: currentVersion, publicKeyHex: issuerSigningPublicKeyHex.toLowerCase() },383  ].filter((key, index, keys) =>384    keys.findIndex((candidate) => candidate.version === key.version && candidate.publicKeyHex === key.publicKeyHex) === index,385  );386  try {387    for (const key of signingKeys) {388      try {389        body = await verifyDeviceManifest(manifest, hexToPubkey(key.publicKeyHex));390        selectedSigningKey = key;391        break;392      } catch { /* try the next immutable trusted key */ }393    }394    if (!body || !selectedSigningKey) return;395  } catch {396    return;397  }398  if (body.issuerDeviceId !== issuer.deviceId) {399    return;400  }401  const verifiedRevocations = (402    await Promise.all(403      body.revoked.map(async (record) => {404        // The outer manifest is authenticated by the directly connected405        // forwarder, but a forwarded revocation retains its original issuer.406        // Resolve that issuer independently from our paired registry and407        // immutable signing-key history; never bind it to the forwarder's key.408        const originalIssuer = await findPairedDeviceById(record.revokedByDeviceId);409        if (!originalIssuer?.signingPublicKeyHex) return null;410        const historicalKeys = (originalIssuer.signingKeyHistory ?? [])411          .filter((key) =>412            Number.isInteger(key.version) &&413            key.version > 0 &&414            /^[0-9a-f]{64}$/i.test(key.publicKeyHex)415          )416          .map((key) => ({417            version: key.version,418            publicKeyHex: key.publicKeyHex.toLowerCase(),419          }));420        const currentKey = originalIssuer.signingPublicKeyHex.toLowerCase();421        const currentVersion = historicalKeys.find(422          (key) => key.publicKeyHex === currentKey,423        )?.version ?? (historicalKeys.reduce(424          (max, key) => Math.max(max, key.version),425          0,426        ) + 1);427        const trustedKeys = [428          ...historicalKeys,429          { version: currentVersion, publicKeyHex: currentKey },430        ].filter((key, index, keys) =>431          keys.findIndex((candidate) =>432            candidate.version === key.version &&433            candidate.publicKeyHex === key.publicKeyHex434          ) === index435        );436        if (437          typeof record.issuerSigningPublicKeyHex !== "string" ||438          !Number.isInteger(record.issuerSigningKeyVersion)439        ) return null;440        const key = trustedKeys.find(441          (candidate) =>442            candidate.version === record.issuerSigningKeyVersion &&443            candidate.publicKeyHex === record.issuerSigningPublicKeyHex!.toLowerCase(),444        );445        if (!key) return null;446        return (await verifyDeviceRevocation(record, hexToPubkey(key.publicKeyHex)))447          ? record448          : null;449      }),450    )451  ).filter((record): record is DeviceRevocation => record !== null);452  body = { ...body, revoked: verifiedRevocations };453454  const ourDeviceId = await getOrCreateDeviceId();455  const masterKey = requireMasterKey();456  const localPairing = await getLocalPairingIdentity();457  const localKeys = { publicKey: localPairing.publicKey, secretKey: localPairing.privateKey };458  try {459    const pendingRegistry: PairedDevice[] = [];460    const pendingSecrets: { deviceId: string; secret: string }[] = [];461    const pendingVouchedIds: string[] = [];462    for (const entry of body.devices) {463      if (entry.deviceId === ourDeviceId || entry.deviceId === issuer.deviceId) continue;464      if (await isDeviceRevoked(entry.deviceId, entry.longTermPublicKeyHex)) continue;465      if ((entry.vouchDepth ?? 0) > (issuer.vouchDepth ?? 0) + 1) continue;466      const existing = await findPairedDeviceById(entry.deviceId);467      const meshRoute = deriveManifestMeshRoute(localKeys.secretKey, localKeys.publicKey, entry);468      if (!existing) {469        if (!meshRoute) continue;470        pendingRegistry.push({471          deviceId: entry.deviceId,472          deviceName: entry.deviceName,473          deviceType: entry.deviceType,474          longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),475          signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),476          wsPort: entry.wsPort,477          relayUrl: meshRoute.relayUrl,478          pairedAt: entry.pairedAt,479          trustSource: "vouched",480          vouchDepth: (issuer.vouchDepth ?? 0) + 1,481        });482        pendingSecrets.push({ deviceId: entry.deviceId, secret: meshRoute.rendezvousSecretHex });483        pendingVouchedIds.push(entry.deviceId);484        continue;485      }486      if (existing.longTermPublicKeyHex && !constantTimeEqualHex(existing.longTermPublicKeyHex, entry.longTermPublicKeyHex)) {487        const knownName = existing.deviceName ?? entry.deviceName;488        notifyPopup({ type: "DEVICE_KEY_ROTATED", payload: { deviceName: knownName, deviceId: entry.deviceId } });489        void recordSyncAlerts([{490          type: "DEVICE_KEY_ROTATED",491          entryId: "",492          entryTitle: knownName,493          deviceName: knownName,494          timestamp: Date.now(),495        }]);496      }497      pendingRegistry.push({498        ...existing,499        deviceId: entry.deviceId,500        deviceName: existing.deviceName ?? entry.deviceName,501        deviceType: entry.deviceType,502        longTermPublicKeyHex: entry.longTermPublicKeyHex.toLowerCase(),503        signingPublicKeyHex: entry.signingPublicKeyHex.toLowerCase(),504        pairedAt: existing.pairedAt ?? entry.pairedAt,505        trustSource: existing.trustSource,506        wsPort: existing.wsPort ?? entry.wsPort,507        relayUrl: existing.trustSource === "vouched" && meshRoute ? meshRoute.relayUrl : existing.relayUrl,508        lastSyncedAt: existing.lastSyncedAt,509      });510      if (existing.trustSource === "vouched" && meshRoute) {511        pendingSecrets.push({ deviceId: entry.deviceId, secret: meshRoute.rendezvousSecretHex });512      }513    }514    const newlyRevoked = await upsertPairedDevicesAndMergeRevocations(515      pendingRegistry,516      body.revoked.filter((r) => r.deviceId !== ourDeviceId),517    );518    for (const deviceId of newlyRevoked) {519      await removePendingVouchedDevice(deviceId);520      void recordSyncAlerts([{521        type: "DEVICE_REVOKED",522        entryId: "",523        entryTitle: deviceId,524        deviceName: issuer.deviceName ?? "paired device",525        timestamp: Date.now(),526      }]);527    }528    for (const pending of pendingSecrets) {529      if (newlyRevoked.includes(pending.deviceId)) continue;530      await setPairSecret(pending.deviceId, pending.secret, masterKey);531    }532    for (const deviceId of pendingVouchedIds) {533      if (newlyRevoked.includes(deviceId)) continue;534      await removePendingVouchedDevice(deviceId);535    }536  } finally {537    masterKey.fill(0);538    localKeys.secretKey.fill(0);539    localKeys.publicKey.fill(0);540  }541}542543function deriveManifestMeshRoute(544  localPrivateKey: Uint8Array,545  localPublicKey: Uint8Array,546  entry: ManifestDeviceEntry,547): { rendezvousSecretHex: string; relayUrl: string } | null {548  try {549    if (!entry.relayUrl) return null;550    const relayUrl = normalizeRelayUrl(entry.relayUrl);551    const secret = deriveMeshRendezvousSecret(552      localPrivateKey,553      localPublicKey,554      hexToPubkey(entry.longTermPublicKeyHex),555    );556    try {557      return {558        rendezvousSecretHex: rendezvousBytesToHex(secret),559        relayUrl,560      };561    } finally {562      secret.fill(0);563    }564  } catch {565    return null;566  }567}568569function notifyPopup(msg: { type: string; payload?: unknown }): void {570  try {571    void chrome.runtime.sendMessage(msg).catch(() => undefined);572  } catch {573    /* popup closed — the durable sync-alert queue remains authoritative */574  }575}576577function requireUnlocked(): void {578  if (!isUnlocked()) throw new VaultLockedError();579}580581function requireRealUnlocked(): void {582  if (!isUnlocked() || isDecoyMode()) throw new VaultLockedError();583}584585// Sync derives everything — vault_id, the Noise static key, the Ed25519586// manifest signing key, and the per-entry envelope keys — from the vault's587// stable root key, NOT the password-derived key. This keeps paired devices'588// identities and envelope keys constant across a master-password change on589// either side (SEV-2-B); two paired devices with independently-rotated590// passwords still share this key and can decrypt each other's entries.591function requireMasterKey(): Uint8Array {592  if (!isUnlocked()) throw new VaultLockedError();593  const hex = getRootKeyHex();594  if (!hex) throw new VaultLockedError();595  return hexToBytes(hex);596}597598async function deriveEntryKey(masterKey: Uint8Array, entryId: string): Promise<CryptoKey> {599  // Null-byte separator (HKDF hardening): entryId cannot contain \x00, so this600  // makes the (entryId, suffix) boundary unambiguous regardless of future id601  // formats. Coordinated wire change — peach-android VaultSyncAdapter derives602  // the identical info; the two MUST stay byte-for-byte in lockstep.603  const info = new TextEncoder().encode(`${entryId}\x00${ENTRY_KEY_INFO_SUFFIX}`);604  const raw = new HKDF(SHA256, masterKey, new Uint8Array(0), info).expand(32);605  return crypto.subtle.importKey(606    "raw",607    raw.buffer as ArrayBuffer,608    { name: "AES-GCM" },609    false,610    ["encrypt", "decrypt"],611  );612}613614async function encryptEntry(key: CryptoKey, entry: VaultEntry): Promise<string> {615  const plaintext = new TextEncoder().encode(JSON.stringify(entry));616  const nonce = crypto.getRandomValues(new Uint8Array(12));617  const aad = new TextEncoder().encode(ENTRY_AAD);618  const ct = await crypto.subtle.encrypt(619    {620      name: "AES-GCM",621      iv: nonce.buffer as ArrayBuffer,622      additionalData: aad.buffer as ArrayBuffer,623      tagLength: 128,624    },625    key,626    plaintext.buffer as ArrayBuffer,627  );628  const ctBytes = new Uint8Array(ct);629  const envelope = new Uint8Array(nonce.length + ctBytes.length);630  envelope.set(nonce, 0);631  envelope.set(ctBytes, nonce.length);632  return bytesToBase64(envelope);633}634635async function decryptEntryOrNull(key: CryptoKey, envelopeB64: string): Promise<VaultEntry | null> {636  try {637    const bytes = base64ToBytes(envelopeB64);638    if (bytes.length < 12 + 16) return null;639    const nonce = bytes.subarray(0, 12);640    const ct = bytes.subarray(12);641    const aad = new TextEncoder().encode(ENTRY_AAD);642    const pt = await crypto.subtle.decrypt(643      {644        name: "AES-GCM",645        iv: nonce.buffer.slice(nonce.byteOffset, nonce.byteOffset + nonce.byteLength) as ArrayBuffer,646        additionalData: aad.buffer as ArrayBuffer,647        tagLength: 128,648      },649      key,650      ct.buffer.slice(ct.byteOffset, ct.byteOffset + ct.byteLength) as ArrayBuffer,651    );652    const json = new TextDecoder().decode(pt);653    const parsed = JSON.parse(json);654    if (!parsed || typeof parsed !== "object" || typeof parsed.id !== "string") return null;655    return parsed as VaultEntry;656  } catch {657    return null;658  }659}660661function hexToBytes(hex: string): Uint8Array {662  if (hex.length % 2 !== 0) throw new Error("hex length must be even");663  const out = new Uint8Array(hex.length / 2);664  for (let i = 0; i < out.length; i++) {665    out[i] = parseInt(hex.slice(i * 2, i * 2 + 2), 16);666  }667  return out;668}669670function bytesToBase64(bytes: Uint8Array): string {671  let bin = "";672  for (let i = 0; i < bytes.length; i++) bin += String.fromCharCode(bytes[i]);673  return btoa(bin);674}675676function bytesToHex(bytes: Uint8Array): string {677  return Array.from(bytes, (byte) => byte.toString(16).padStart(2, "0")).join("");678}679680function base64ToBytes(b64: string): Uint8Array {681  const bin = atob(b64);682  const out = new Uint8Array(bin.length);683  for (let i = 0; i < bin.length; i++) out[i] = bin.charCodeAt(i);684  return out;685}