VaultRepository.kt

1package com.peachpasswords.vault23import kotlinx.coroutines.flow.MutableStateFlow4import kotlinx.coroutines.flow.StateFlow5import kotlinx.coroutines.flow.asStateFlow6import kotlinx.coroutines.sync.Mutex7import kotlinx.coroutines.sync.withLock8import java.security.SecureRandom9import java.text.Normalizer10import kotlinx.serialization.json.Json11import android.util.Log12import com.peachpasswords.BuildConfig13import kotlinx.serialization.json.JsonElement14import kotlinx.serialization.json.JsonNull15import kotlinx.serialization.json.JsonObject16import kotlinx.serialization.json.JsonPrimitive17import java.util.Base6418import java.util.UUID19import javax.inject.Inject20import javax.inject.Singleton2122/** Lenient parser for the Codex vault-blob wrapper only. */23private val CodexJson = Json { ignoreUnknownKeys = true; isLenient = true }2425private fun b64(bytes: ByteArray): String = Base64.getEncoder().withoutPadding().encodeToString(bytes)26private fun unb64(s: String): ByteArray = Base64.getDecoder().decode(s)2728/** Cap on retained past passwords per entry. Mirrors the browser PASSWORD_HISTORY_MAX. */29private const val PASSWORD_HISTORY_MAX = 5030private const val VAULT_HISTORY_MAX = 53132sealed interface UnlockResult {33    data object Success : UnlockResult34    data object WrongPassword : UnlockResult35    data class Error(val reason: String) : UnlockResult36}3738sealed interface CreateVaultResult {39    data object Success : CreateVaultResult40    data class Error(val reason: String) : CreateVaultResult41}4243sealed interface AdoptVaultResult {44    data class Success(val vaultId: String) : AdoptVaultResult45    data class Error(val reason: String) : AdoptVaultResult46}4748/**49 * In-memory vault session backed by [VaultStore]. Faithful port of the browser50 * `vault.ts` semantics that matter for correctness:51 *52 *  - Two-slot at rest: slot A is the real (encrypted) vault, slot B a size-matched53 *    noise blob so a fresh install shows two similarly-shaped records.54 *  - Every modifiedAt/deletedAt uses [VaultCrypto.monotonicEntryTimestamp] so a55 *    deletion always wins last-write-wins against an in-flight edit.56 *  - Local writes bump the version counter; sync-applied writes do NOT (so a57 *    sync round never cascades into another outbound sync).58 *  - add/update/delete roll back in-memory state if the disk write fails.59 *  - destroyVault never touches the Pro license (separate store).60 */61@Singleton62class VaultRepository @Inject constructor(63    private val store: VaultStorage,64) {65    private val mutex = Mutex()66    private val rng = SecureRandom()6768    private var derivedKey: ByteArray? = null69    private var rootKey: ByteArray? = null70    private var entryList: MutableList<VaultEntry> = mutableListOf()71    private var duressConfigured: Boolean = false72    private var recoveryWordHash: String? = null73    private var recoveryWordsSet: Boolean = false74    /** True while a decoy (duress) session is active — persistence targets the decoy slot. */75    private var decoyMode: Boolean = false7677    private val _isUnlocked = MutableStateFlow(false)78    val isUnlocked: StateFlow<Boolean> = _isUnlocked.asStateFlow()7980    private val _entries = MutableStateFlow<List<VaultEntry>>(emptyList())81    /** Active (non-deleted) entryList. */82    val entries: StateFlow<List<VaultEntry>> = _entries.asStateFlow()8384    private val _settings = MutableStateFlow(VaultSettings())85    val settings: StateFlow<VaultSettings> = _settings.asStateFlow()8687    fun hasVault(): Boolean = store.hasVault()8889    // ---- Codex (printed paper backup) -------------------------------------9091    /**92     * The at-rest slot-A envelope as base64 JSON `{"a": <StoredVault>}` — the93     * Codex payload's vaultBlob. Slot B is noise, so it is omitted. Restorable94     * on any device that has the master password. Null when no vault exists.95     */96    fun codexVaultBlobBase64(): String? {97        val slotA = store.loadSlotA() ?: return null98        val wrapper = """{"a":${VaultCodec.encodeSlot(slotA)}}"""99        return Base64.getUrlEncoder().withoutPadding().encodeToString(wrapper.toByteArray(Charsets.UTF_8))100    }101102    /**103     * Replace the local vault from a Codex blob, then unlock with [password].104     * Writes slot A (and a size-matched noise slot B) before unlocking so the105     * restored vault is at rest exactly as a freshly-created one would be.106     */107    /** A slot is stored either as a JSON string (browser) or inline object (Android). */108    private fun JsonElement?.asSlotJson(): String? = when {109        this == null || this is JsonNull -> null110        this is JsonPrimitive && isString -> content111        else -> toString()112    }113114    suspend fun restoreFromCodex(vaultBlobBase64: String, password: String): UnlockResult = mutex.withLock {115        return try {116            val wrapperJson = String(Base64.getUrlDecoder().decode(vaultBlobBase64), Charsets.UTF_8)117            // Parsed as JSON, not matched with a regex. The wrapper is118            // `{ "a": <slot>, "b": <slot|null> }` and the browser — which119            // generates most real Codexes — writes each slot as a JSON120            // *string*, with "b" present. A regex looking for an object121            // literal under "a" at the very end of the wrapper matches122            // neither of those, so every browser-generated Codex failed here123            // with "invalid_codex_blob" after decoding perfectly.124            val wrapper = CodexJson.parseToJsonElement(wrapperJson) as? JsonObject125                ?: return UnlockResult.Error("invalid_codex_blob")126            val slotJson = wrapper["a"].asSlotJson() ?: return UnlockResult.Error("invalid_codex_blob")127            // A Codex printed from the browser carries a browser-shaped slot,128            // which is the common case — most Codexes are printed there. It is129            // translated to Android's shape (see BrowserSlot) rather than130            // rejected. A translation failure is a wrong password, not a bad131            // blob: the codes decoded fine, the password just didn't open them.132            val slotA = VaultCodec.decodeSlot(slotJson)133                ?: BrowserSlot.parse(slotJson)?.let {134                    BrowserSlot.toAndroidSlot(it, password) ?: return UnlockResult.WrongPassword135                }136                ?: return UnlockResult.Error("invalid_codex_blob")137            if (!store.writeSlotA(slotA)) return UnlockResult.Error("storage_write_failed")138            // Carry the real slot B across when the Codex has one — it holds a139            // duress vault, which noise would silently destroy.140            val slotB = wrapper["b"].asSlotJson()141            if (slotB != null) {142                store.writeSlotB(Base64.getEncoder().encodeToString(slotB.toByteArray(Charsets.UTF_8)))143            } else {144                writeMatchingNoiseSlotB(slotA)145            }146            store.stampLocalMutation()147            unlockLocked(password)148        } catch (e: Exception) {149            // A raw kotlinx parse error ("Unexpected JSON token at offset N")150            // reaching the user says nothing about WHICH json failed — the151            // wrapper, or the payload decrypted out of it. Codex screens are152            // FLAG_SECURE so this can't be screenshotted either. Debug builds153            // log the structure around the failure; alphanumerics are masked so154            // no ciphertext or vault content lands in a log.155            if (BuildConfig.DEBUG) Log.w("PeachCodex", codexFailureShape(vaultBlobBase64, e))156            UnlockResult.Error(e.message ?: "restore_failed")157        }158    }159160    /** Debug-only: structure of a failed Codex restore, with content masked. */161    private fun codexFailureShape(vaultBlobBase64: String, e: Exception): String = runCatching {162        val wrapperJson = String(Base64.getUrlDecoder().decode(vaultBlobBase64), Charsets.UTF_8)163        val offset = Regex("offset (\\d+)").find(e.message.orEmpty())?.groupValues?.get(1)?.toIntOrNull()164        val window = offset?.let {165            val from = (it - 40).coerceAtLeast(0)166            val to = (it + 40).coerceAtMost(wrapperJson.length)167            wrapperJson.substring(from, to).replace(Regex("[A-Za-z0-9+/=_-]"), "x")168        }169        val wrapper = runCatching { CodexJson.parseToJsonElement(wrapperJson) as? JsonObject }.getOrNull()170        val slot = wrapper?.get("a")171        buildString {172            append("codex restore failed: ").append(e::class.simpleName).append(": ").append(e.message)173            append(" | blobBase64=").append(vaultBlobBase64.length)174            append(" wrapperChars=").append(wrapperJson.length)175            append(" wrapperParses=").append(wrapper != null)176            append(" keys=").append(wrapper?.keys)177            append(" slotAKind=").append(178                when {179                    slot == null -> "absent"180                    slot is JsonPrimitive && slot.isString -> "string"181                    slot is JsonObject -> "object:" + slot.keys182                    else -> slot::class.simpleName183                },184            )185            if (window != null) append(" masked@").append(offset).append("=").append(window)186        }187    }.getOrElse { "codex restore failed: ${e.message} (shape unavailable: $it)" }188189    suspend fun createVault(password: String): CreateVaultResult = mutex.withLock {190        return try {191            val salt = VaultCrypto.generateSalt()192            val key = VaultCrypto.deriveKey(password, salt)193            entryList = mutableListOf()194            duressConfigured = false195            recoveryWordHash = null196            recoveryWordsSet = false197            decoyMode = false198            rootKey = generateRecoverableRootKey()199            val slotA = sealSlotA(key, salt)200            if (!store.writeSlotA(slotA)) return CreateVaultResult.Error("storage_write_failed")201            writeMatchingNoiseSlotB(slotA)202            store.stampLocalMutation()203            store.writeSettings(_settings.value)204            derivedKey = key205            publish()206            _isUnlocked.value = true207            CreateVaultResult.Success208        } catch (e: Exception) {209            CreateVaultResult.Error(e.message ?: "create_failed")210        }211    }212213    suspend fun createVaultFromRootKey(password: String, rootKeyHex: String): AdoptVaultResult = mutex.withLock {214        if (password.isEmpty()) return AdoptVaultResult.Error("ADOPT_INVALID_PASSWORD")215        if (!rootKeyHex.matches(Regex("^[0-9a-f]{64}$"))) {216            return AdoptVaultResult.Error("ADOPT_INVALID_ROOT_KEY: expected 64 lowercase hex chars")217        }218        var adoptedRootKey: ByteArray? = null219        var nextDerivedKey: ByteArray? = null220        var sessionRootKey: ByteArray? = null221        return try {222            adoptedRootKey = hexToRootKey(rootKeyHex)223            if (adoptedRootKey.size != VaultCrypto.KEY_SIZE) {224                return AdoptVaultResult.Error("ADOPT_INVALID_ROOT_KEY: expected 32 bytes")225            }226            val vaultId = com.peachpasswords.sync.computeVaultId(adoptedRootKey)227            val salt = VaultCrypto.generateSalt()228            nextDerivedKey = VaultCrypto.deriveKey(password, salt)229            sessionRootKey = adoptedRootKey.copyOf()230            val payload = VaultPayload(231                entries = emptyList(),232                duressConfigured = false,233                rootKeyB64 = b64(sessionRootKey),234                recoveryWordHash = null,235                recoveryWordsSet = false,236            )237            val blob = b64(VaultCrypto.encrypt(VaultCodec.encode(payload), nextDerivedKey, VaultCrypto.AAD_SLOT_A))238            val slotA = StoredVault(version = 1, salt = b64(salt), blob = blob)239            if (!store.writeSlotA(slotA)) return AdoptVaultResult.Error("storage_write_failed")240            writeMatchingNoiseSlotB(slotA)241            store.stampLocalMutation()242            store.writeSettings(_settings.value)243244            val previousDerivedKey = derivedKey245            val previousRootKey = rootKey246            derivedKey = nextDerivedKey247            rootKey = sessionRootKey248            nextDerivedKey = null249            sessionRootKey = null250            entryList = mutableListOf()251            duressConfigured = false252            recoveryWordHash = null253            recoveryWordsSet = false254            decoyMode = false255            publish()256            _isUnlocked.value = true257            previousDerivedKey?.let(VaultCrypto::zero)258            previousRootKey?.let(VaultCrypto::zero)259            AdoptVaultResult.Success(vaultId)260        } catch (e: Exception) {261            AdoptVaultResult.Error(e.message ?: "adoption_create_failed")262        } finally {263            adoptedRootKey?.let(VaultCrypto::zero)264            nextDerivedKey?.let(VaultCrypto::zero)265            sessionRootKey?.let(VaultCrypto::zero)266        }267    }268269    suspend fun unlock(password: String): UnlockResult = mutex.withLock { unlockLocked(password) }270271    /** Unlock body without acquiring the mutex — callers must already hold it. */272    private fun unlockLocked(password: String): UnlockResult {273        val slotA = store.loadSlotA() ?: return UnlockResult.Error("no_vault")274        val key = VaultCrypto.deriveKey(password, unb64(slotA.salt))275        val payload = try {276            VaultCodec.decode(VaultCrypto.decrypt(unb64(slotA.blob), key, VaultCrypto.AAD_SLOT_A))277        } catch (_: Exception) {278            VaultCrypto.zero(key)279            // LV-1: a vault sealed before NFC normalization with a non-NFC280            // password derives a different key now. If the supplied password is281            // not already in NFC form, retry with the raw (un-normalized) bytes.282            if (password != Normalizer.normalize(password, Normalizer.Form.NFC)) {283                val legacy = tryLegacyRawUnlock(password, slotA)284                if (legacy != null) return legacy285            }286            return UnlockResult.WrongPassword287        }288        return adoptSlotA(key, payload)289    }290291    /**292     * LV-1 legacy fallback: unlock a slot-A vault that was sealed under the raw293     * (un-normalized) password bytes. On success the slot is HEALED — re-sealed294     * under the NFC-normalized key — so every future unlock takes the normal295     * path. Returns null when the raw key also fails (genuinely wrong password).296     */297    private fun tryLegacyRawUnlock(password: String, slotA: StoredVault): UnlockResult? {298        val rawKey = VaultCrypto.deriveKeyRaw(password, unb64(slotA.salt))299        val payload = try {300            VaultCodec.decode(VaultCrypto.decrypt(unb64(slotA.blob), rawKey, VaultCrypto.AAD_SLOT_A))301        } catch (_: Exception) {302            VaultCrypto.zero(rawKey)303            return null304        }305        // Heal: re-seal slot A under the NFC key (mirrors changePassword's306        // re-seal). Escrows carry forward unchanged — only the wrapping rotates.307        val newSalt = VaultCrypto.generateSalt()308        val newKey = VaultCrypto.deriveKey(password, newSalt)309        val healed = try {310            val blob = b64(VaultCrypto.encrypt(VaultCodec.encode(payload), newKey, VaultCrypto.AAD_SLOT_A))311            val next = StoredVault(312                version = slotA.version,313                salt = b64(newSalt),314                blob = blob,315                recoveryEscrow = slotA.recoveryEscrow,316                rootKeyEscrow = slotA.rootKeyEscrow,317            )318            if (store.writeSlotA(next)) {319                writeMatchingNoiseSlotB(next)320                store.stampLocalMutation()321                true322            } else {323                false324            }325        } catch (_: Exception) {326            false327        }328        return if (healed) {329            VaultCrypto.zero(rawKey)330            adoptSlotA(newKey, payload) // session key now matches the re-sealed slot331        } else {332            VaultCrypto.zero(newKey)333            adoptSlotA(rawKey, payload) // heal failed — keep using the raw key334        }335    }336337    /** Adopt a derived slot-A [key]/[payload] as the live (real-vault) session. */338    private fun adoptSlotA(key: ByteArray, payload: VaultPayload): UnlockResult {339        return try {340            derivedKey = key341            decoyMode = false342            entryList = payload.entries.toMutableList()343            duressConfigured = payload.duressConfigured344            recoveryWordHash = payload.recoveryWordHash345            recoveryWordsSet = payload.recoveryWordsSet346            _settings.value = store.loadSettings()347            ensureRootKey(payload)348            autoPurgeExpiredTrash()349            publish()350            _isUnlocked.value = true351            UnlockResult.Success352        } catch (e: Exception) {353            UnlockResult.Error(e.message ?: "unlock_failed")354        }355    }356357    // ---- Constant-time unlock (MF-5) --------------------------------------358359    /**360     * A slot-A unlock that has been derived but not yet adopted. Holds the live361     * Argon2id key and decoded payload so the caller can derive several candidates362     * concurrently and commit only the winner. The key is owned by this token until363     * [commitSlotAUnlock] adopts it or [discardSlotAUnlock] zeroes it.364     */365    class SlotAUnlock internal constructor(366        internal val key: ByteArray,367        internal val payload: VaultPayload,368    )369370    /**371     * Derive the slot-A key and decrypt its payload WITHOUT mutating session state.372     * Pure computation (no mutex), so it can run concurrently with other candidate373     * derivations before the caller decides which to commit (MF-5). Returns null on374     * no-vault or wrong password (the derived key is zeroed on a tag mismatch).375     */376    fun tryUnlockSlotA(password: String): SlotAUnlock? {377        val slotA = store.loadSlotA() ?: return null378        val key = VaultCrypto.deriveKey(password, unb64(slotA.salt))379        return try {380            val payload = VaultCodec.decode(VaultCrypto.decrypt(unb64(slotA.blob), key, VaultCrypto.AAD_SLOT_A))381            SlotAUnlock(key, payload)382        } catch (_: Exception) {383            VaultCrypto.zero(key)384            null385        }386    }387388    /** Adopt a previously-derived [SlotAUnlock] as the live session. */389    suspend fun commitSlotAUnlock(unlock: SlotAUnlock): UnlockResult = mutex.withLock {390        adoptSlotA(unlock.key, unlock.payload)391    }392393    /** Zero a derived [SlotAUnlock] that will not be adopted. */394    fun discardSlotAUnlock(unlock: SlotAUnlock) = VaultCrypto.zero(unlock.key)395396    // ---- Duress slot B (MF-6) ---------------------------------------------397398    /**399     * A duress-slot (slot B) unlock derived but not yet adopted. Holds the live key400     * and decoded decoy payload so it can be derived concurrently with slot A and401     * only committed if the duress passphrase was the one entered (MF-5/MF-6).402     */403    class DuressUnlock internal constructor(404        internal val key: ByteArray,405        internal val payload: VaultPayload,406    )407408    /**409     * Try to decrypt the duress slot (slot B) with [password] WITHOUT mutating the410     * session. Success means the entered password is the duress passphrase that keys411     * slot B — indistinguishable from the real slot A at the lock screen. Pure412     * computation (no mutex), safe to run concurrently with [tryUnlockSlotA].413     * Returns null when no duress slot exists or the password is not the duress one.414     */415    fun tryUnlockDuress(password: String): DuressUnlock? {416        val slot = store.loadDecoySlot() ?: return null417        val key = VaultCrypto.deriveKey(password, unb64(slot.salt))418        return try {419            val payload = VaultCodec.decode(VaultCrypto.decrypt(unb64(slot.blob), key, VaultCrypto.AAD_SLOT_A))420            DuressUnlock(key, payload)421        } catch (_: Exception) {422            VaultCrypto.zero(key)423            null424        }425    }426427    /** Adopt a derived [DuressUnlock] as a live decoy session (edits persist to slot B only). */428    suspend fun commitDuressUnlock(unlock: DuressUnlock): UnlockResult = mutex.withLock {429        return try {430            derivedKey = unlock.key431            decoyMode = true432            entryList = unlock.payload.entries.toMutableList()433            duressConfigured = false434            recoveryWordHash = unlock.payload.recoveryWordHash435            recoveryWordsSet = unlock.payload.recoveryWordsSet436            rootKey = if (unlock.payload.rootKeyB64.isNotBlank()) unb64(unlock.payload.rootKeyB64)437                      else VaultCrypto.generateRootKey()438            _settings.value = store.loadSettings()439            publish()440            _isUnlocked.value = true441            UnlockResult.Success442        } catch (e: Exception) {443            UnlockResult.Error(e.message ?: "decoy_unlock_failed")444        }445    }446447    /** Zero a derived [DuressUnlock] that will not be adopted. */448    fun discardDuressUnlock(unlock: DuressUnlock) = VaultCrypto.zero(unlock.key)449450    /**451     * Configure the duress vault (MF-6): seal a fresh, empty decoy payload under an452     * Argon2id key derived from [duressPassphrase] (fresh salt) into slot B. The453     * passphrase is never stored — only its ability to decrypt slot B proves it.454     * Requires the real vault to be unlocked and not itself a decoy session.455     */456    suspend fun setDuressPassphrase(duressPassphrase: String): Boolean = mutex.withLock {457        if (derivedKey == null || decoyMode) return false458        // Reject a duress passphrase that also opens the real vault: it would make the459        // lock screen ambiguous (both slots would decrypt for the same input).460        tryUnlockSlotA(duressPassphrase)?.let { discardSlotAUnlock(it); return false }461        return try {462            val salt = VaultCrypto.generateSalt()463            val key = VaultCrypto.deriveKey(duressPassphrase, salt)464            // An empty decoy vault with its own fresh sync root key — nothing real leaks.465            val decoyPayload = VaultPayload(entries = emptyList(), rootKeyB64 = b64(VaultCrypto.generateRootKey()))466            val plaintext = VaultCodec.encode(decoyPayload)467            val blob = b64(VaultCrypto.encrypt(plaintext, key, VaultCrypto.AAD_SLOT_A))468            VaultCrypto.zero(key)469            VaultCrypto.zero(plaintext)470            val ok = store.writeDecoySlot(StoredVault(version = 1, salt = b64(salt), blob = blob))471            if (ok) {472                duressConfigured = true473                runCatching { persistSlotA(bumpVersion = false) }474            }475            ok476        } catch (_: Exception) {477            false478        }479    }480481    /** Tear down the duress vault: drop slot B and the duress flag on the real payload. */482    suspend fun clearDuress(): Boolean = mutex.withLock {483        store.clearDecoySlot()484        if (derivedKey != null && !decoyMode) {485            duressConfigured = false486            runCatching { persistSlotA(bumpVersion = false) }487        }488        true489    }490491    /** Unlock with an already-derived AES-256 key (biometric path). */492    suspend fun unlockWithKey(key: ByteArray): UnlockResult = mutex.withLock {493        val slotA = store.loadSlotA() ?: return UnlockResult.Error("no_vault")494        return try {495            val payload = VaultCodec.decode(496                VaultCrypto.decrypt(unb64(slotA.blob), key, VaultCrypto.AAD_SLOT_A),497            )498            derivedKey = key.copyOf()499            decoyMode = false500            entryList = payload.entries.toMutableList()501            duressConfigured = payload.duressConfigured502            recoveryWordHash = payload.recoveryWordHash503            recoveryWordsSet = payload.recoveryWordsSet504            _settings.value = store.loadSettings()505            ensureRootKey(payload)506            autoPurgeExpiredTrash()507            publish()508            _isUnlocked.value = true509            UnlockResult.Success510        } catch (_: Exception) {511            UnlockResult.WrongPassword512        }513    }514515    fun lock() {516        derivedKey?.let(VaultCrypto::zero)517        rootKey?.let(VaultCrypto::zero)518        derivedKey = null519        rootKey = null520        entryList = mutableListOf()521        duressConfigured = false522        recoveryWordHash = null523        recoveryWordsSet = false524        decoyMode = false525        _entries.value = emptyList()526        _isUnlocked.value = false527    }528529    @Volatile private var suppressNextBackgroundLock = false530531    /**532     * Call immediately before launching a system Activity (a SAF file533     * picker/save dialog, a share sheet) that briefly takes the whole process534     * out of the foreground as an expected part of an in-app flow — not a535     * genuine user backgrounding. ProcessLifecycleOwner.onStop can't tell the536     * two apart on its own (it fires for both), and without this, exporting or537     * importing a file silently locked and wiped the vault mid-flow the moment538     * the picker took over, before its result ever reached the app.539     */540    fun expectTransientBackground() {541        suppressNextBackgroundLock = true542    }543544    /** Consumed once by the next background-lock check; see [expectTransientBackground]. */545    fun consumeTransientBackgroundSuppression(): Boolean {546        val suppressed = suppressNextBackgroundLock547        suppressNextBackgroundLock = false548        return suppressed549    }550551    // ---- Sync identity ----------------------------------------------------552553    /**554     * The vault's stable sync master key (a copy). Caller must zero it. Backs555     * vault_id, the Noise static key, the Ed25519 manifest key, and per-entry556     * envelope keys. Null when locked. See [VaultPayload.rootKeyB64].557     */558    fun syncMasterKey(): ByteArray? = rootKey?.copyOf()559560    /** Stable per-vault id two paired devices must share to sync. Null when locked. */561    fun syncVaultId(): String? = rootKey?.let { com.peachpasswords.sync.computeVaultId(it) }562563    /**564     * Browser parity (MV-8): rotate the sync identity by replacing the stable565     * root key. Entries remain under the master-password key, while sync566     * credentials, vault_id, and recovery words all change.567     */568    suspend fun rotateSyncIdentity(): Boolean = mutex.withLock {569        val key = derivedKey ?: return false570        if (decoyMode) return false571        val priorSlot = store.loadSlotA() ?: return false572        val priorRootKey = rootKey ?: return false573        val priorRecoveryHash = recoveryWordHash574        val priorRecoverySet = recoveryWordsSet575        val nextRootKey = generateRecoverableRootKey()576        val nextWords = rootKeyToWords(nextRootKey)577578        try {579            takeVaultSnapshot("local_save")580            rootKey = nextRootKey581            recoveryWordHash = recoveryWordsHash(nextWords)582            recoveryWordsSet = false583584            val nextRecoveryEscrow = buildRecoveryEscrow(nextWords)585                ?: throw IllegalStateException("recovery_escrow_failed")586            val nextRootKeyEscrow = buildRootKeyEscrow(nextWords)587                ?: throw IllegalStateException("root_escrow_failed")588            val plaintext = VaultCodec.encode(currentPayload())589            val blob = try {590                b64(VaultCrypto.encrypt(plaintext, key, VaultCrypto.AAD_SLOT_A))591            } finally {592                VaultCrypto.zero(plaintext)593            }594            val nextSlot = priorSlot.copy(595                blob = blob,596                recoveryEscrow = nextRecoveryEscrow,597                rootKeyEscrow = nextRootKeyEscrow,598            )599            if (!store.writeSlotA(nextSlot)) throw IllegalStateException("storage_write_failed")600            try {601                writeMatchingNoiseSlotB(nextSlot)602                store.stampLocalMutation()603            } catch (e: Exception) {604                store.writeSlotA(priorSlot)605                throw e606            }607            VaultCrypto.zero(priorRootKey)608            publish()609            true610        } catch (_: Exception) {611            rootKey = priorRootKey612            recoveryWordHash = priorRecoveryHash613            recoveryWordsSet = priorRecoverySet614            VaultCrypto.zero(nextRootKey)615            store.writeSlotA(priorSlot)616            false617        }618    }619620    /**621     * A copy of the live Argon2id-derived vault key, for biometric escrow only622     * (wrapped under a hardware KeyStore key on biometric enable). Null when623     * locked. Caller must [VaultCrypto.zero] it after use.624     */625    fun currentVaultKey(): ByteArray? = derivedKey?.copyOf()626627    suspend fun changePassword(oldPassword: String, newPassword: String): Boolean = mutex.withLock {628        val slotA = store.loadSlotA() ?: return false629        return try {630            val oldKey = VaultCrypto.deriveKey(oldPassword, unb64(slotA.salt))631            val payload = VaultCodec.decode(632                VaultCrypto.decrypt(unb64(slotA.blob), oldKey, VaultCrypto.AAD_SLOT_A),633            )634            val newSalt = VaultCrypto.generateSalt()635            val newKey = VaultCrypto.deriveKey(newPassword, newSalt)636            // Re-seal the existing payload under the new key/salt.637            val plaintext = VaultCodec.encode(payload)638            val blob = b64(VaultCrypto.encrypt(plaintext, newKey, VaultCrypto.AAD_SLOT_A))639            // The escrow seals the slot-A PLAINTEXT, which a password change does not640            // alter — only the wrapping changes — so carry it forward; rebuilding the641            // StoredVault from scratch would silently drop it.642            // Carry BOTH escrows forward unchanged: each seals plaintext/root-key643            // content that a password change does not alter — only the slot-A644            // wrapping rotates. The root-key escrow staying stable across password645            // changes matches the browser (`vault.ts:363-364`).646            val next = StoredVault(647                version = slotA.version,648                salt = b64(newSalt),649                blob = blob,650                recoveryEscrow = slotA.recoveryEscrow,651                rootKeyEscrow = slotA.rootKeyEscrow,652            )653            if (!store.writeSlotA(next)) return false654            writeMatchingNoiseSlotB(next)655            store.stampLocalMutation()656            VaultCrypto.zero(oldKey)657            derivedKey?.let(VaultCrypto::zero)658            derivedKey = newKey659            true660        } catch (_: Exception) {661            false662        }663    }664665    /**666     * Irreversible wipe. Locks the session and clears every vault key. The Pro667     * license is in a separate store and is preserved by construction.668     */669    suspend fun destroyVault() = mutex.withLock {670        lock()671        store.clearVault()672        store.clearDecoySlot()673    }674675    // ---- Entry CRUD -------------------------------------------------------676677    suspend fun addEntry(draft: VaultEntry): VaultEntry = mutex.withLock {678        requireUnlocked()679        val stamp = VaultCrypto.monotonicEntryTimestamp()680        val now = System.currentTimeMillis()681        val entry = withDerivedLast4(draft.copy(682            id = draft.id.ifBlank { UUID.randomUUID().toString() },683            createdAt = if (draft.createdAt > 0) draft.createdAt else now,684            modifiedAt = stamp,685            passwordChangedAt = if (!draft.password.isNullOrEmpty()) stamp else draft.passwordChangedAt,686        ))687        val rollback = entryList.toMutableList()688        entryList.add(entry)689        persistOrRollback(rollback)690        entry691    }692693    /**694     * Insert many entries with a single encrypt-and-write at the end.695     *696     * Importing a real vault through [addEntry] was quadratic: every entry took697     * the lock and re-encrypted and rewrote the whole vault, so an 806-entry698     * restore did 806 full-vault writes and hung the app long enough to ANR.699     * Rolls back to the pre-import list if the one write fails, matching700     * [addEntry]'s all-or-nothing behaviour.701     */702    suspend fun addEntries(drafts: List<VaultEntry>): Int = mutex.withLock {703        requireUnlocked()704        if (drafts.isEmpty()) return 0705        val rollback = entryList.toMutableList()706        val now = System.currentTimeMillis()707        for (draft in drafts) {708            val stamp = VaultCrypto.monotonicEntryTimestamp()709            entryList.add(710                withDerivedLast4(711                    draft.copy(712                        id = draft.id.ifBlank { UUID.randomUUID().toString() },713                        createdAt = if (draft.createdAt > 0) draft.createdAt else now,714                        modifiedAt = stamp,715                        passwordChangedAt = if (!draft.password.isNullOrEmpty()) stamp else draft.passwordChangedAt,716                    ),717                ),718            )719        }720        persistOrRollback(rollback)721        return drafts.size722    }723724    suspend fun updateEntry(patch: VaultEntry): VaultEntry = mutex.withLock {725        requireUnlocked()726        val idx = entryList.indexOfFirst { it.id == patch.id }727        if (idx == -1 || entryList[idx].deletedAt != null) throw IllegalStateException("entry_not_found")728        val current = entryList[idx]729        val stamp = VaultCrypto.monotonicEntryTimestamp(current.modifiedAt)730        // Only refresh passwordChangedAt when the password value actually changes.731        val passwordChanged = patch.password != null && patch.password != current.password732        // Capture the outgoing password (newest first) so the user can reveal/copy/733        // restore it later. History is computed authoritatively from `current`, not734        // the patch — updateEntry is a full-entry replace, so trusting patch's value735        // would let a stale form clobber the real history. Record the age the old736        // password carried, skip an empty prior, and skip an immediate exact dupe737        // (e.g. restore-then-restore). Capped at PASSWORD_HISTORY_MAX.738        val priorPassword = current.password739        val shouldCapture = passwordChanged &&740            !priorPassword.isNullOrEmpty() &&741            current.passwordHistory?.firstOrNull()?.password != priorPassword742        val nextHistory = if (shouldCapture) {743            (listOf(PasswordHistoryItem(priorPassword!!, current.passwordChangedAt ?: current.createdAt)) +744                (current.passwordHistory ?: emptyList())).take(PASSWORD_HISTORY_MAX)745        } else {746            current.passwordHistory747        }748        val updated = withDerivedLast4(patch.copy(749            createdAt = current.createdAt,750            modifiedAt = stamp,751            passwordChangedAt = if (passwordChanged) stamp else current.passwordChangedAt,752            passwordHistory = nextHistory,753        ))754        val rollback = entryList.toMutableList()755        entryList[idx] = updated756        persistOrRollback(rollback)757        updated758    }759760    /** Soft-delete: writes a tombstone whose timestamp beats any in-flight edit. */761    suspend fun deleteEntry(id: String) = mutex.withLock {762        requireUnlocked()763        val idx = entryList.indexOfFirst { it.id == id }764        if (idx == -1 || entryList[idx].deletedAt != null) throw IllegalStateException("entry_not_found")765        val current = entryList[idx]766        val stamp = VaultCrypto.monotonicEntryTimestamp(current.modifiedAt)767        val rollback = entryList.toMutableList()768        entryList[idx] = current.copy(deletedAt = stamp, modifiedAt = stamp)769        persistOrRollback(rollback)770    }771772    suspend fun restoreEntry(id: String) = mutex.withLock {773        requireUnlocked()774        val idx = entryList.indexOfFirst { it.id == id && it.deletedAt != null }775        if (idx == -1) throw IllegalStateException("deleted entry not found")776        val current = entryList[idx]777        val rollback = entryList.toMutableList()778        entryList[idx] = current.copy(deletedAt = null, modifiedAt = VaultCrypto.monotonicEntryTimestamp(current.modifiedAt))779        persistOrRollback(rollback)780    }781782    /** Permanent delete — no tombstone, no recovery. */783    suspend fun purgeEntry(id: String) = mutex.withLock {784        requireUnlocked()785        val idx = entryList.indexOfFirst { it.id == id && it.deletedAt != null }786        if (idx == -1) throw IllegalStateException("deleted entry not found")787        val rollback = entryList.toMutableList()788        entryList.removeAt(idx)789        persistOrRollback(rollback)790    }791792    /** Permanently empty the trash — hard-deletes every soft-deleted entry. */793    suspend fun purgeDeletedEntries(): Int = mutex.withLock {794        requireUnlocked()795        val rollback = entryList.toMutableList()796        val before = entryList.size797        entryList.removeAll { it.deletedAt != null }798        val removed = before - entryList.size799        if (removed > 0) persistOrRollback(rollback)800        removed801    }802803    /** Browser parity: number of active entries that dedupe would move to trash. */804    suspend fun countDuplicateEntries(): Int = mutex.withLock {805        requireUnlocked()806        countDuplicateEntriesLocked()807    }808809    /**810     * Browser parity: soft-delete duplicate entries, keeping the most recently811     * modified member of each group. Refuse in decoy mode so the duress vault is812     * not reshaped into a forensically distinct state.813     */814    suspend fun deduplicateEntries(): Int = mutex.withLock {815        requireUnlocked()816        if (decoyMode) throw IllegalStateException("deduplicate disabled in decoy mode")817        val active = entryList.filter { it.deletedAt == null }818        val keepIds = mutableSetOf<String>()819        active.groupBy { it.duplicateKey() }.values.forEach { group ->820            keepIds += group.maxBy { it.modifiedAt.takeIf { ts -> ts > 0 } ?: it.createdAt }.id821        }822823        val rollback = entryList.toMutableList()824        var removed = 0825        entryList = entryList.map { entry ->826            if (entry.deletedAt == null && entry.id !in keepIds) {827                removed++828                val stamp = VaultCrypto.monotonicEntryTimestamp(entry.modifiedAt)829                entry.copy(deletedAt = stamp, modifiedAt = stamp)830            } else {831                entry832            }833        }.toMutableList()834        if (removed > 0) persistOrRollback(rollback)835        removed836    }837838    fun getEntries(): List<VaultEntry> = entryList.filter { it.deletedAt == null }839    fun getEntry(id: String): VaultEntry? = entryList.firstOrNull { it.id == id && it.deletedAt == null }840    fun getDeletedEntries(): List<VaultEntry> =841        entryList.filter { it.deletedAt != null }.sortedByDescending { it.deletedAt }842843    /** Active entries, optionally narrowed to those carrying [tagFilter]. */844    fun getActiveEntries(tagFilter: String? = null): List<VaultEntry> {845        val active = entryList.filter { it.deletedAt == null }846        if (tagFilter == null) return active847        val needle = tagFilter.trim().lowercase()848        return active.filter { e -> e.tags?.any { it.equals(needle, ignoreCase = true) } == true }849    }850851    /** Sorted, de-duplicated tags across all active entries. */852    fun getDistinctTags(): List<String> =853        entryList.asSequence()854            .filter { it.deletedAt == null }855            .flatMap { it.tags?.asSequence() ?: emptySequence() }856            .map { it.trim().lowercase() }857            .filter { it.isNotEmpty() }858            .distinct()859            .sorted()860            .toList()861862    /**863     * Distinct non-blank values for an identity field across active entries,864     * most-frequently-used first. Supports "username" and "email"; unknown field865     * names return an empty list. Values keep original casing (deduped866     * case-insensitively) so a suggestion matches what the user typed.867     */868    fun getDistinctFieldValues(field: String): List<String> {869        val select: (VaultEntry) -> String? = when (field) {870            "username" -> { e -> e.username }871            "email" -> { e -> e.email }872            else -> return emptyList()873        }874        return entryList.asSequence()875            .filter { it.deletedAt == null }876            .mapNotNull { select(it)?.trim() }877            .filter { it.isNotEmpty() }878            .groupingBy { it.lowercase() }879            .aggregate { _, acc: Pair<String, Int>?, value, _ ->880                Pair(acc?.first ?: value, (acc?.second ?: 0) + 1)881            }882            .values883            .sortedWith(compareByDescending<Pair<String, Int>> { it.second }.thenBy { it.first.lowercase() })884            .map { it.first }885    }886887    fun getTombstones(): List<Tombstone> =888        entryList.filter { it.deletedAt != null }.map { Tombstone(it.id, it.deletedAt!!) }889    fun getVaultVersion(): Long = store.version()890    fun getVaultHistory(): List<VaultSnapshot> = store.loadVaultHistory().snapshots891892    suspend fun restoreVaultSnapshot(snapshotId: String): Boolean = mutex.withLock {893        val snapshot = store.loadVaultHistory().snapshots.firstOrNull { it.id == snapshotId } ?: return false894        val restoredA = VaultCodec.decodeSlot(snapshot.vault_a) ?: return false895        takeVaultSnapshot("restore")896        if (!store.writeSlotA(restoredA)) return false897        if (!store.writeSlotB(snapshot.vault_b)) return false898        store.stampLocalMutation()899        lock()900        true901    }902903    // ---- Sync apply (does NOT advance the version) ------------------------904905    /**906     * Apply remote entryList + tombstones with per-entry last-write-wins. Persists907     * WITHOUT bumping the version counter, so a sync round cannot cascade into908     * another outbound sync. Returns the number of locally-applied changes.909     */910    suspend fun applyMergedRemoteEntries(911        remoteEntries: List<VaultEntry>,912        remoteTombstones: List<Tombstone>,913    ): Int = mutex.withLock {914        requireUnlocked()915        val tombMap = remoteTombstones.associate { it.id to it.deletedAt }916        var applied = 0917        val byId = entryList.associateBy { it.id }.toMutableMap()918919        for (remote in remoteEntries) {920            val tomb = tombMap[remote.id]921            if (tomb != null && tomb >= remote.modifiedAt) continue922            val local = byId[remote.id]923            if (local == null) {924                entryList.add(remote); byId[remote.id] = remote; applied++925            } else if (remote.modifiedAt > local.modifiedAt) {926                val i = entryList.indexOfFirst { it.id == local.id }927                if (i != -1) { entryList[i] = remote; byId[remote.id] = remote; applied++ }928            }929        }930931        for ((id, deletedAt) in tombMap) {932            val local = byId[id] ?: continue933            if (local.deletedAt != null && local.deletedAt >= deletedAt) continue934            if (deletedAt < local.modifiedAt) continue935            val i = entryList.indexOfFirst { it.id == id }936            if (i != -1) { entryList[i] = local.copy(deletedAt = deletedAt, modifiedAt = deletedAt); applied++ }937        }938939        if (applied > 0) {940            persistSlotA(bumpVersion = false, snapshotReason = "sync_received")941            publish()942        }943        applied944    }945946    suspend fun updateSettings(settings: VaultSettings) = mutex.withLock {947        _settings.value = settings948        store.writeSettings(settings)949    }950951    // ---- Recovery words (vault metadata) ----------------------------------952953    /** True once the user has confirmed their recovery words for this vault. */954    fun isRecoveryWordsSet(): Boolean = recoveryWordsSet955956    /**957     * Record the BLAKE3 hash of the confirmed recovery words and mark them set.958     * Persisted without bumping the version — recovery metadata is local-only and959     * is not an entry mutation paired devices should sync against.960     */961    suspend fun setRecoveryWords(words: List<String>): Boolean = mutex.withLock {962        requireUnlocked()963        recoveryWordHash = recoveryWordsHash(words)964        recoveryWordsSet = true965        // Seal TWO escrows (MF-1): the browser-byte-compatible root-key escrow966        // (cross-platform recovery of the sync root key) and Android's whole-payload967        // escrow (offline forgot-password restore of entries). Both derive their key968        // from the same `wordsToRootKeyMaterial` IKM but use distinct AADs.969        runCatching {970            persistSlotAWithEscrows(buildRecoveryEscrow(words), buildRootKeyEscrow(words))971        }.getOrDefault(false)972    }973974    /** Verify entered words against the stored recovery hash. */975    fun verifyRecoveryWords(words: List<String>): Boolean {976        val stored = recoveryWordHash ?: return false977        return stored == recoveryWordsHash(words)978    }979980    // ---- Recovery escrow (forgot-password) --------------------------------981982    /** True at rest if this vault has any recovery escrow the recovery flow can use. */983    fun hasRecoveryEscrow(): Boolean =984        store.loadSlotA()?.let { it.recoveryEscrow != null || it.rootKeyEscrow != null } ?: false985986    /**987     * Attempt to unlock the vault using the 12 BIP39 recovery [words] instead of988     * the master password. On success the slot-A plaintext sealed in the escrow is989     * adopted as the live session (entries, rootKey, settings), but no Argon2id990     * password key exists yet — call [resetPasswordWithRecoveryWords] next to set a991     * new password and finish unlocking. Returns false when there is no escrow, the992     * words fail the BIP39 checksum, or the words are wrong (GCM tag mismatch).993     *994     * Unlike the brief's `unlockWithRecoveryWords(): ByteArray?`, there is no995     * detached vault key to return here — slot A is wrapped under the rotating996     * Argon2id key — so this opens the escrowed payload directly.997     */998    suspend fun unlockWithRecoveryWords(words: List<String>): Boolean = mutex.withLock {999        val slotA = store.loadSlotA() ?: return false1000        if (words.size != 12 || findInvalidWords(words).isNotEmpty()) return false10011002        // Prefer Android's whole-payload escrow: a full offline restore of entries,1003        // root key, and settings. Present for Android-created vaults.1004        slotA.recoveryEscrow?.let { escrow ->1005            val material = runCatching { wordsToRootKeyMaterial(words) }.getOrNull() ?: return@let1006            val recoveryKey = deriveRecoveryKey(material, unb64(escrow.salt))1007            val keyBytes = recoveryKey.encoded1008            try {1009                val plaintext = VaultCrypto.decrypt(unb64(escrow.blob), keyBytes, VaultCrypto.AAD_RECOVERY)1010                val payload = VaultCodec.decode(plaintext)1011                decoyMode = false1012                entryList = payload.entries.toMutableList()1013                duressConfigured = payload.duressConfigured1014                recoveryWordHash = payload.recoveryWordHash1015                recoveryWordsSet = payload.recoveryWordsSet1016                rootKey = if (payload.rootKeyB64.isNotBlank()) unb64(payload.rootKeyB64)1017                          else generateRecoverableRootKey()1018                _settings.value = store.loadSettings()1019                VaultCrypto.zero(plaintext)1020                return true1021            } catch (_: Exception) {1022                // Wrong words against this escrow — fall through to the root-key escrow.1023            } finally {1024                VaultCrypto.zero(material)1025                VaultCrypto.zero(keyBytes)1026            }1027        }10281029        // Browser-format vault (only the root-key escrow): recover the 32-byte root1030        // key (sync identity) and reset the password; entries return via sync. This1031        // is exactly the browser's recovery semantics (`messages.ts:312-347`).1032        slotA.rootKeyEscrow?.let { escrow ->1033            val rk = unsealRootKeyEscrow(words, escrow) ?: return false1034            decoyMode = false1035            entryList = mutableListOf()1036            duressConfigured = false1037            recoveryWordHash = recoveryWordsHash(words)1038            recoveryWordsSet = true1039            rootKey = rk1040            _settings.value = store.loadSettings()1041            return true1042        }1043        return false1044    }10451046    /**1047     * After [unlockWithRecoveryWords] succeeds, set a brand-new master password:1048     * re-seal slot A under a fresh Argon2id key, rotate the escrow under the same1049     * words, mark the session fully unlocked, and publish. Returns false if called1050     * without a prior successful recovery unlock (no in-memory root key).1051     *1052     * Folds the brief's `resetPasswordWithRecoveryKey(vaultKey, …)` + `unlock(…)`1053     * into one step, since there is no detached vault key here.1054     */1055    suspend fun resetPasswordWithRecoveryWords(1056        words: List<String>,1057        newPassword: String,1058    ): Boolean = mutex.withLock {1059        if (rootKey == null) return false // must have recovered first1060        return try {1061            val newSalt = VaultCrypto.generateSalt()1062            val newKey = VaultCrypto.deriveKey(newPassword, newSalt)1063            val plaintext = VaultCodec.encode(currentPayload())1064            val blob = b64(VaultCrypto.encrypt(plaintext, newKey, VaultCrypto.AAD_SLOT_A))1065            val prior = store.loadSlotA()1066            // Rebuild both escrows against the recovered session so their salts rotate1067            // with the password reset; fall back to the prior escrows if rebuild fails1068            // (e.g. a checksum-invalid phrase). The same 12 words keep working.1069            val valid = words.size == 12 && findInvalidWords(words).isEmpty()1070            val freshRecovery = if (valid) buildRecoveryEscrow(words) ?: prior?.recoveryEscrow else prior?.recoveryEscrow1071            val freshRootKey = if (valid) buildRootKeyEscrow(words) ?: prior?.rootKeyEscrow else prior?.rootKeyEscrow1072            val next = StoredVault(1073                version = prior?.version ?: 1,1074                salt = b64(newSalt),1075                blob = blob,1076                recoveryEscrow = freshRecovery,1077                rootKeyEscrow = freshRootKey,1078            )1079            if (!store.writeSlotA(next)) return false1080            writeMatchingNoiseSlotB(next)1081            store.stampLocalMutation()1082            derivedKey?.let(VaultCrypto::zero)1083            derivedKey = newKey1084            VaultCrypto.zero(plaintext)1085            publish()1086            _isUnlocked.value = true1087            true1088        } catch (_: Exception) {1089            false1090        }1091    }10921093    /**1094     * Seal the current slot-A plaintext under a key derived from the 12 BIP391095     * recovery [words] (Android offline-restore escrow). IKM is the browser's1096     * `wordsToRootKeyMaterial` (MF-1), AAD is the string [VaultCrypto.AAD_RECOVERY].1097     * Returns null for a checksum-invalid phrase.1098     */1099    private fun buildRecoveryEscrow(words: List<String>): RecoveryEscrow? {1100        if (words.size != 12 || findInvalidWords(words).isNotEmpty()) return null1101        val material = runCatching { wordsToRootKeyMaterial(words) }.getOrNull() ?: return null1102        val salt = VaultCrypto.generateSalt()1103        val recoveryKey = deriveRecoveryKey(material, salt)1104        val keyBytes = recoveryKey.encoded1105        val plaintext = VaultCodec.encode(currentPayload())1106        return try {1107            val sealed = VaultCrypto.encrypt(plaintext, keyBytes, VaultCrypto.AAD_RECOVERY)1108            RecoveryEscrow(salt = b64(salt), blob = b64(sealed))1109        } finally {1110            VaultCrypto.zero(material)1111            VaultCrypto.zero(keyBytes)1112            VaultCrypto.zero(plaintext)1113        }1114    }11151116    /**1117     * Seal ONLY the 32-byte root key under a key the recovery [words] derive,1118     * byte-for-byte the browser algorithm (MF-1): plaintext = lowercase ASCII hex1119     * of the root key, IKM = `wordsToRootKeyMaterial`, HKDF salt random-16,1120     * info `peach-recovery-v1`, AES-256-GCM AAD = 0x01. The same 12 words unwrap1121     * the same root key on the browser. Returns null with no in-memory root key or1122     * a checksum-invalid phrase.1123     */1124    private fun buildRootKeyEscrow(words: List<String>): RootKeyEscrow? {1125        if (words.size != 12 || findInvalidWords(words).isNotEmpty()) return null1126        val rk = rootKey ?: return null1127        val material = runCatching { wordsToRootKeyMaterial(words) }.getOrNull() ?: return null1128        val salt = VaultCrypto.generateSalt()1129        val recoveryKey = deriveRecoveryKey(material, salt)1130        val keyBytes = recoveryKey.encoded1131        val plaintext = rootKeyToHex(rk).toByteArray(Charsets.US_ASCII)1132        return try {1133            // combined = nonce(12) || ciphertext || tag(16)1134            val combined = VaultCrypto.encrypt(plaintext, keyBytes, VaultCrypto.AAD_RECOVERY_ROOTKEY)1135            val nonce = combined.copyOfRange(0, VaultCrypto.NONCE_SIZE)1136            val ctTag = combined.copyOfRange(VaultCrypto.NONCE_SIZE, combined.size)1137            val tag = ctTag.copyOfRange(ctTag.size - 16, ctTag.size)1138            val ct = ctTag.copyOfRange(0, ctTag.size - 16)1139            RootKeyEscrow(salt = b64(salt), wrappedRootKey = b64(ct), nonce = b64(nonce), tag = b64(tag))1140        } finally {1141            VaultCrypto.zero(material)1142            VaultCrypto.zero(keyBytes)1143            VaultCrypto.zero(plaintext)1144        }1145    }11461147    /** Unwrap the 32-byte root key from a browser-compatible [escrow]; null on wrong words. */1148    private fun unsealRootKeyEscrow(words: List<String>, escrow: RootKeyEscrow): ByteArray? {1149        val material = runCatching { wordsToRootKeyMaterial(words) }.getOrNull() ?: return null1150        val recoveryKey = deriveRecoveryKey(material, unb64(escrow.salt))1151        val keyBytes = recoveryKey.encoded1152        return try {1153            val combined = unb64(escrow.nonce) + unb64(escrow.wrappedRootKey) + unb64(escrow.tag)1154            val pt = VaultCrypto.decrypt(combined, keyBytes, VaultCrypto.AAD_RECOVERY_ROOTKEY)1155            hexToRootKey(String(pt, Charsets.US_ASCII))1156        } catch (_: Exception) {1157            null1158        } finally {1159            VaultCrypto.zero(material)1160            VaultCrypto.zero(keyBytes)1161        }1162    }11631164    /**1165     * Re-seal slot A from the current in-memory state under the live key, carrying1166     * both [recoveryEscrow] and [rootKeyEscrow] onto the written record. Never runs1167     * in decoy mode (recovery is never offered for the decoy) and persists without1168     * a version bump, like the recovery-words metadata write it replaces.1169     */1170    private fun persistSlotAWithEscrows(1171        recoveryEscrow: RecoveryEscrow?,1172        rootKeyEscrow: RootKeyEscrow?,1173    ): Boolean {1174        val key = derivedKey ?: throw IllegalStateException("vault_locked")1175        if (decoyMode) return false1176        val prior = store.loadSlotA() ?: throw IllegalStateException("missing slot A")1177        val plaintext = VaultCodec.encode(currentPayload())1178        val blob = b64(VaultCrypto.encrypt(plaintext, key, VaultCrypto.AAD_SLOT_A))1179        val next = prior.copy(1180            blob = blob,1181            recoveryEscrow = recoveryEscrow ?: prior.recoveryEscrow,1182            rootKeyEscrow = rootKeyEscrow ?: prior.rootKeyEscrow,1183        )1184        if (!store.writeSlotA(next)) return false1185        try {1186            writeMatchingNoiseSlotB(next)1187        } catch (e: Exception) {1188            store.writeSlotA(prior)1189            throw e1190        }1191        return true1192    }11931194    // ---- Internals --------------------------------------------------------11951196    private fun requireUnlocked() {1197        if (derivedKey == null) throw IllegalStateException("vault_locked")1198    }11991200    private fun countDuplicateEntriesLocked(): Int {1201        val seen = mutableMapOf<String, VaultEntry>()1202        var duplicates = 01203        for (entry in entryList.filter { it.deletedAt == null }) {1204            val key = entry.duplicateKey()1205            val existing = seen[key]1206            if (existing == null) {1207                seen[key] = entry1208            } else {1209                duplicates++1210                val entryStamp = entry.modifiedAt.takeIf { it > 0 } ?: entry.createdAt1211                val existingStamp = existing.modifiedAt.takeIf { it > 0 } ?: existing.createdAt1212                if (entryStamp > existingStamp) seen[key] = entry1213            }1214        }1215        return duplicates1216    }12171218    private fun VaultEntry.duplicateKey(): String {1219        if (type == "note") return "note|${title.lowercase()}"1220        val passkeyData = passkey1221        if (passkeyData != null) {1222            return "passkey|${passkeyData.rpId.lowercase()}|${passkeyData.userName.lowercase()}"1223        }1224        return "login|${title.lowercase()}|${url.orEmpty().lowercase()}|${username.orEmpty().lowercase()}"1225    }12261227    private fun takeVaultSnapshot(reason: String) {1228        runCatching {1229            val slotA = store.loadSlotA() ?: return1230            val vaultA = VaultCodec.encodeSlot(slotA)1231            val vaultB = store.loadSlotB() ?: slotA.blob1232            val history = store.loadVaultHistory()1233            val latest = history.snapshots.firstOrNull()1234            if (latest?.vault_a == vaultA && latest.vault_b == vaultB) return1235            val entryCount = if (derivedKey != null && !decoyMode) {1236                bucketEntryCount(entryList.count { it.deletedAt == null })1237            } else {1238                null1239            }1240            val snapshot = VaultSnapshot(1241                id = UUID.randomUUID().toString(),1242                savedAt = System.currentTimeMillis(),1243                reason = reason,1244                vault_a = vaultA,1245                vault_b = vaultB,1246                entryCount = entryCount,1247            )1248            store.writeVaultHistory(1249                history.copy(snapshots = (listOf(snapshot) + history.snapshots).take(VAULT_HISTORY_MAX)),1250            )1251        }1252    }12531254    private fun bucketEntryCount(n: Int): Int = when {1255        n <= 0 -> 01256        n <= 10 -> 101257        n <= 25 -> 251258        n <= 50 -> 501259        n <= 100 -> 1001260        n <= 250 -> 2501261        n <= 500 -> 5001262        else -> ((n + 499) / 500) * 5001263    }12641265    /**1266     * Keep [VaultEntry.last4] in sync with the card number for card entries (MF-3),1267     * so it is stored explicitly and survives the sync wire format rather than being1268     * re-derived at render time. Non-card entries pass through unchanged.1269     */1270    private fun withDerivedLast4(entry: VaultEntry): VaultEntry {1271        if (!entry.isCard()) return entry1272        val digits = entry.cardNumber?.filter { it.isDigit() } ?: ""1273        return entry.copy(last4 = if (digits.length >= 4) digits.takeLast(4) else null)1274    }12751276    /**1277     * On unlock, hard-delete trashed entries older than the retention window.1278     * A null or non-positive [VaultSettings.trashRetentionDays] means "never"1279     * (the app's "Never" option), so nothing is purged. Persists without a1280     * version bump and without touching the publish state (caller publishes).1281     */1282    private fun autoPurgeExpiredTrash() {1283        val days = _settings.value.trashRetentionDays ?: return1284        if (days <= 0) return1285        val cutoff = System.currentTimeMillis() - days.toLong() * 24L * 60L * 60L * 1000L1286        val before = entryList.size1287        entryList.removeAll { it.deletedAt != null && it.deletedAt < cutoff }1288        if (entryList.size != before) runCatching { persistSlotA(bumpVersion = false) }1289    }12901291    /** The slot-A plaintext envelope for the current in-memory session. */1292    private fun currentPayload(): VaultPayload =1293        VaultPayload(1294            entries = entryList.toList(),1295            duressConfigured = duressConfigured,1296            rootKeyB64 = rootKey?.let(::b64) ?: "",1297            recoveryWordHash = recoveryWordHash,1298            recoveryWordsSet = recoveryWordsSet,1299        )13001301    /**1302     * Adopt the payload's root key, lazily minting one for legacy payloads.1303     * A freshly-minted key is persisted WITHOUT bumping the version — adopting1304     * a root key is not a mutation paired devices should sync against.1305     */1306    private fun ensureRootKey(payload: VaultPayload) {1307        if (payload.rootKeyB64.isNotBlank()) {1308            rootKey = unb64(payload.rootKeyB64)1309            return1310        }1311        rootKey = generateRecoverableRootKey()1312        runCatching { persistSlotA(bumpVersion = false) }1313    }13141315    private fun publish() {1316        _entries.value = entryList.filter { it.deletedAt == null }1317    }13181319    private fun sealSlotA(key: ByteArray, salt: ByteArray): StoredVault {1320        val plaintext = VaultCodec.encode(currentPayload())1321        val blob = b64(VaultCrypto.encrypt(plaintext, key, VaultCrypto.AAD_SLOT_A))1322        return StoredVault(version = 1, salt = b64(salt), blob = blob)1323    }13241325    private fun writeMatchingNoiseSlotB(slotA: StoredVault) {1326        // Size the noise so its base64 length matches slot A's blob (MN-1): with the1327        // plaintext now bucket-padded, an at-rest observer sees two equal-length slots1328        // and cannot pick the real one by size. b64(N bytes) ≈ N*4/3 chars.1329        val approxBytes = (slotA.blob.length * 3 / 4).coerceAtLeast(VaultCrypto.NONCE_SIZE + 16)1330        val noise = ByteArray(approxBytes).also(rng::nextBytes)1331        store.writeSlotB(b64(noise))1332    }13331334    /** Re-seal slot A from the current in-memory state under the live key. */1335    private fun persistSlotA(bumpVersion: Boolean, snapshotReason: String? = "local_save"): Boolean {1336        val key = derivedKey ?: throw IllegalStateException("vault_locked")1337        // Decoy sessions persist to the decoy slot only — never touch the real slot A.1338        if (decoyMode) {1339            val prior = store.loadDecoySlot() ?: throw IllegalStateException("missing decoy slot")1340            val plaintext = VaultCodec.encode(currentPayload())1341            val blob = b64(VaultCrypto.encrypt(plaintext, key, VaultCrypto.AAD_SLOT_A))1342            return store.writeDecoySlot(prior.copy(blob = blob))1343        }1344        val prior = store.loadSlotA() ?: throw IllegalStateException("missing slot A")1345        if (snapshotReason != null) takeVaultSnapshot(snapshotReason)1346        val plaintext = VaultCodec.encode(currentPayload())1347        val blob = b64(VaultCrypto.encrypt(plaintext, key, VaultCrypto.AAD_SLOT_A))1348        val next = prior.copy(blob = blob)1349        if (!store.writeSlotA(next)) return false1350        // Slot A committed — keep slot B size-matched, then advance the version1351        // for local writes only. Restore slot A if a later step fails.1352        try {1353            writeMatchingNoiseSlotB(next)1354            if (bumpVersion) store.stampLocalMutation()1355        } catch (e: Exception) {1356            store.writeSlotA(prior)1357            throw e1358        }1359        return true1360    }13611362    /** Persist a local mutation, rolling the in-memory list back on failure. */1363    private fun persistOrRollback(rollback: MutableList<VaultEntry>) {1364        try {1365            if (!persistSlotA(bumpVersion = true)) {1366                entryList = rollback1367                throw IllegalStateException("storage_write_failed")1368            }1369        } catch (e: Exception) {1370            entryList = rollback1371            throw e1372        }1373        publish()1374    }1375}