VaultSyncAdapter.kt

1package com.peachpasswords.sync23import com.peachpasswords.vault.Tombstone4import com.peachpasswords.vault.VaultEntry5import com.peachpasswords.vault.VaultRepository6import kotlinx.serialization.json.Json7import org.bouncycastle.crypto.digests.SHA256Digest8import org.bouncycastle.crypto.generators.HKDFBytesGenerator9import org.bouncycastle.crypto.params.HKDFParameters10import java.security.SecureRandom11import java.util.Base6412import javax.crypto.Cipher13import javax.crypto.spec.GCMParameterSpec14import javax.crypto.spec.SecretKeySpec1516/**17 * Production [ChirpSyncVaultAdapter] backing the coordinator with the live18 * [VaultRepository]. Exact port of the browser `chirp-sync-vault-adapter.ts`:19 * the coordinator only ever moves opaque base64 envelopes; plaintext crosses20 * this boundary and nowhere else.21 *22 * Envelope cipher: AES-GCM under a PER-ENTRY key23 *   HKDF-SHA256(ikm = syncMasterKey, salt = "", info = entryId + "\u0000" + "sync-entry-v1")24 * with a random 12-byte nonce and aad = "peach-sync-entry-v1". Binding the key25 * to the entry id means a ciphertext minted for one slot cannot be replayed26 * into another — [applyEntries] rejects any envelope whose decrypted id does27 * not match the map key it arrived under. Both paired devices hold the same28 * syncMasterKey (same vault root key), so keys match without negotiation; the29 * Noise XX session is a second, independent encryption layer on top.30 */31class VaultSyncAdapter(32    private val repo: VaultRepository,33    private val ourDeviceId: String,34    private val pairedDevices: PairedDeviceRegistry? = null,35    private val pendingVouched: PendingVouchedRegistry? = null,36    private val syncAlerts: SyncAlertRecorder? = null,37    private val remoteDeviceName: String = "paired device",38    override val supportsDeviceManifest: Boolean = pairedDevices != null && pendingVouched != null,39) : ChirpSyncVaultAdapter {4041    override suspend fun computeVaultId(): String =42        repo.syncVaultId() ?: throw VaultLockedException()4344    override suspend fun getOurDeviceId(): String = ourDeviceId4546    override suspend fun getLocalVersion(): Long = repo.getVaultVersion()4748    override suspend fun buildEntryManifest(): Map<String, Long> =49        repo.getEntries().associate { it.id to it.modifiedAt }5051    override suspend fun buildTombstoneManifest(): Map<String, Long> =52        repo.getTombstones().associate { it.id to it.deletedAt }5354    override suspend fun getEncryptedEntries(entryIds: List<String>): Map<String, String> {55        val master = requireMasterKey()56        try {57            val out = LinkedHashMap<String, String>()58            for (id in entryIds) {59                val entry = repo.getEntry(id) ?: continue60                out[id] = encryptEntry(deriveEntryKey(master, id), entry)61            }62            return out63        } finally {64            master.fill(0)65        }66    }6768    override suspend fun applyEntries(entries: Map<String, String>) {69        val before = if (syncAlerts != null) repo.getEntries() else emptyList()70        val master = requireMasterKey()71        val decrypted = try {72            entries.mapNotNull { (id, envelope) ->73                val entry = decryptEntryOrNull(deriveEntryKey(master, id), envelope)74                // The map key is the authority on id — refuse a swapped envelope75                // so a ciphertext can't poison a different entry slot.76                if (entry != null && entry.id == id) entry else null77            }78        } finally {79            master.fill(0)80        }81        if (decrypted.isNotEmpty()) {82            val applied = repo.applyMergedRemoteEntries(decrypted, emptyList())83            if (applied > 0) {84                syncAlerts?.record(85                    remoteEntrySyncAlerts(86                        localEntries = before,87                        remoteEntries = decrypted,88                        deviceName = remoteDeviceName,89                        nowMs = System.currentTimeMillis(),90                    ),91                )92            }93        }94    }9596    override suspend fun applyTombstones(tombstones: Map<String, Long>) {97        val before = if (syncAlerts != null) repo.getEntries() else emptyList()98        val cleaned = tombstones99            .filterValues { it > 0L }100            .map { (id, ts) -> Tombstone(id, ts) }101        if (cleaned.isNotEmpty()) {102            val applied = repo.applyMergedRemoteEntries(emptyList(), cleaned)103            if (applied > 0) {104                syncAlerts?.record(105                    remoteTombstoneSyncAlerts(106                        localEntries = before,107                        remoteTombstones = cleaned,108                        deviceName = remoteDeviceName,109                        nowMs = System.currentTimeMillis(),110                    ),111                )112            }113        }114    }115116    override suspend fun buildOutgoingDeviceManifest(): SignedDeviceManifest? {117        val registry = pairedDevices ?: return null118        val master = requireMasterKey()119        return try {120            val signing = deriveSyncSigningKeypair(master, ourDeviceId)121            val devices = registry.getAll().mapNotNull { it.toManifestEntry() }122            buildSignedDeviceManifest(ourDeviceId, devices, signing.privateKey)123        } finally {124            master.fill(0)125        }126    }127128    override suspend fun applyIncomingDeviceManifest(manifest: SignedDeviceManifest) {129        val registry = pairedDevices ?: return130        val pending = pendingVouched ?: return131        val issuerId = manifest.body.issuerDeviceId132        val issuer = registry.get(issuerId) ?: return133        // Match the browser (`applyVerifiedPeerManifest` in sync-vault-adapter.ts):134        // trust a manifest only from a DIRECTLY paired issuer. This previously135        // keyed on deviceType == "extension" instead, which got both halves136        // wrong: it ignored manifests from other phones/tablets, so mesh trust137        // could never propagate between native devices (the whole point of the138        // mesh now that phones are the listening side), and it never checked139        // trustSource at all — so a merely VOUCHED device could introduce140        // further devices, chaining trust transitively in a way the browser141        // deliberately refuses.142        if (issuer.trustSource != "direct") return143        val signingKey = issuer.signingPublicKeyHex?.lowercase()?.takeIf { it.length == 64 } ?: return144        val body = verifyDeviceManifest(manifest, hexToPubkey(signingKey)) ?: return145        if (body.issuerDeviceId != issuer.deviceId) return146147        for (entry in body.devices) {148            if (entry.deviceId == ourDeviceId || entry.deviceId == issuer.deviceId) continue149            val existing = registry.get(entry.deviceId)150            if (existing == null) {151                pending.upsert(152                    PendingVouchedDevice(153                        deviceId = entry.deviceId,154                        deviceName = entry.deviceName,155                        deviceType = entry.deviceType,156                        longTermPublicKeyHex = entry.longTermPublicKeyHex.lowercase(),157                        signingPublicKeyHex = entry.signingPublicKeyHex.lowercase(),158                        wsPort = entry.wsPort,159                        pairedAt = entry.pairedAt,160                        receivedAt = System.currentTimeMillis(),161                        vouchedByDeviceId = issuer.deviceId,162                    ),163                )164            } else {165                deviceKeyRotationAlert(existing, entry, System.currentTimeMillis())?.let { alert ->166                    syncAlerts?.record(listOf(alert))167                }168                registry.upsert(169                    existing.copy(170                        deviceName = entry.deviceName,171                        deviceType = entry.deviceType,172                        longTermPublicKeyHex = entry.longTermPublicKeyHex.lowercase(),173                        signingPublicKeyHex = entry.signingPublicKeyHex.lowercase(),174                        wsPort = existing.wsPort ?: entry.wsPort,175                        pairedAt = existing.pairedAt,176                        trustSource = existing.trustSource ?: "direct",177                    ),178                )179            }180        }181    }182183    private fun requireMasterKey(): ByteArray =184        repo.syncMasterKey() ?: throw VaultLockedException()185186    private fun deriveEntryKey(masterKey: ByteArray, entryId: String): ByteArray {187        // Null-byte separator (HKDF hardening): entryId cannot contain U+0000, so188        // the (entryId, suffix) boundary is unambiguous regardless of future id189        // formats. Coordinated wire change — peach-browser deriveEntryKey produces190        // the identical info bytes; the two MUST stay byte-for-byte in lockstep.191        val info = (entryId + "\u0000" + ENTRY_KEY_INFO_SUFFIX).toByteArray(Charsets.UTF_8)192        val gen = HKDFBytesGenerator(SHA256Digest())193        gen.init(HKDFParameters(masterKey, ByteArray(0), info))194        return ByteArray(32).also { gen.generateBytes(it, 0, it.size) }195    }196197    private fun encryptEntry(key: ByteArray, entry: VaultEntry): String {198        val plaintext = entryJson.encodeToString(VaultEntry.serializer(), entry).toByteArray(Charsets.UTF_8)199        val nonce = ByteArray(12).also(rng::nextBytes)200        val cipher = Cipher.getInstance("AES/GCM/NoPadding")201        cipher.init(Cipher.ENCRYPT_MODE, SecretKeySpec(key, "AES"), GCMParameterSpec(128, nonce))202        cipher.updateAAD(ENTRY_AAD)203        val ct = cipher.doFinal(plaintext)204        return b64(nonce + ct)205    }206207    private fun decryptEntryOrNull(key: ByteArray, envelopeB64: String): VaultEntry? = try {208        val bytes = unb64(envelopeB64)209        if (bytes.size < 12 + 16) null else {210            val nonce = bytes.copyOfRange(0, 12)211            val ct = bytes.copyOfRange(12, bytes.size)212            val cipher = Cipher.getInstance("AES/GCM/NoPadding")213            cipher.init(Cipher.DECRYPT_MODE, SecretKeySpec(key, "AES"), GCMParameterSpec(128, nonce))214            cipher.updateAAD(ENTRY_AAD)215            val pt = cipher.doFinal(ct)216            entryJson.decodeFromString(VaultEntry.serializer(), String(pt, Charsets.UTF_8))217        }218    } catch (_: Exception) {219        null220    }221222    private companion object {223        const val ENTRY_KEY_INFO_SUFFIX = "sync-entry-v1"224        val ENTRY_AAD = "peach-sync-entry-v1".toByteArray(Charsets.UTF_8)225        val rng = SecureRandom()226        val entryJson = Json { encodeDefaults = false; ignoreUnknownKeys = true }227        fun b64(b: ByteArray): String = Base64.getEncoder().encodeToString(b)228        fun unb64(s: String): ByteArray = Base64.getDecoder().decode(s)229    }230}231232class VaultLockedException : Exception("vault_locked")