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 [SyncVaultAdapter] backing the coordinator with the live18 * [VaultRepository]. Exact port of the browser `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 KK reconnect 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 var remoteDeviceName: String = "paired device",38    override val supportsDeviceManifest: Boolean = pairedDevices != null && pendingVouched != null,39) : SyncVaultAdapter {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 master = requireMasterKey()70        val decrypted = try {71            entries.mapNotNull { (id, envelope) ->72                val entry = decryptEntryOrNull(deriveEntryKey(master, id), envelope)73                // The map key is the authority on id — refuse a swapped envelope74                // so a ciphertext can't poison a different entry slot.75                if (entry != null && entry.id == id) entry else null76            }77        } finally {78            master.fill(0)79        }80        if (decrypted.isNotEmpty()) {81            repo.applyMergedRemoteEntries(decrypted, emptyList())82        }83    }8485    override suspend fun applyTombstones(tombstones: Map<String, Long>) {86        val cleaned = tombstones87            .filterValues { it > 0L }88            .map { (id, ts) -> Tombstone(id, ts) }89        if (cleaned.isNotEmpty()) {90            repo.applyMergedRemoteEntries(emptyList(), cleaned)91        }92    }9394    override fun bindAuthenticatedPeer(peer: PairedDevice) {95        remoteDeviceName = peer.deviceName?.takeIf { it.isNotBlank() }96            ?: peer.deviceId.takeIf { it.isNotBlank() }97            ?: "paired device"98    }99100    override suspend fun buildOutgoingDeviceManifest(): SignedDeviceManifest? {101        val registry = pairedDevices ?: return null102        val master = requireMasterKey()103        return try {104            val signing = deriveSyncSigningKeypair(master, ourDeviceId)105            val revoked = registry.listRevocations()106            val revokedIds = revoked.map { it.deviceId }.toSet()107            val devices = registry.getAll()108                .filterNot { revokedIds.contains(it.deviceId) }109                .mapNotNull { it.toManifestEntry() }110            buildSignedDeviceManifest(111                ourDeviceId,112                devices,113                signing.privateKey,114                revoked = revoked,115            )116        } finally {117            master.fill(0)118        }119    }120121    override suspend fun applyIncomingDeviceManifest(122        manifest: SignedDeviceManifest,123        authenticatedRemoteStaticPublicKey: ByteArray,124    ) {125        val registry = pairedDevices ?: return126        val pending = pendingVouched ?: return127        if (authenticatedRemoteStaticPublicKey.size != 32) return128        val issuer = registry.getByPubkey(pubkeyToHex(authenticatedRemoteStaticPublicKey)) ?: return129        // Match the browser (`applyVerifiedPeerManifest` in sync-vault-adapter.ts):130        // trust a manifest only from a DIRECTLY paired issuer. This previously131        // keyed on deviceType == "extension" instead, which got both halves132        // wrong: it ignored manifests from other phones/tablets, so mesh trust133        // could never propagate between native devices (the whole point of the134        // mesh now that phones are the listening side), and it never checked135        // trustSource at all — so a merely VOUCHED device could introduce136        // further devices, chaining trust transitively in a way the browser137        // deliberately refuses.138        if (issuer.trustSource != "direct") return139        val signingKey = issuer.signingPublicKeyHex?.lowercase()?.takeIf { it.length == 64 } ?: return140        val body = verifyDeviceManifest(manifest, hexToPubkey(signingKey)) ?: return141        if (body.issuerDeviceId != issuer.deviceId) return142143        // Revocations are absorbed BEFORE any vouching, so a manifest that both144        // revokes and re-vouches the same device cannot race itself. A peer may145        // not revoke US — that would let one compromised device sever the whole146        // mesh — so our own id is filtered out first.147        val newlyRevoked = registry.mergeRevocations(148            body.revoked.filterNot { it.deviceId == ourDeviceId },149        )150        for (deviceId in newlyRevoked) {151            registry.remove(deviceId)152            pending.remove(deviceId)153            syncAlerts?.record(154                listOf(155                    SyncAlert(156                        type = SyncAlertType.DEVICE_REVOKED,157                        deviceName = issuer.deviceName ?: "paired device",158                        entryTitle = deviceId,159                        timestamp = System.currentTimeMillis(),160                    ),161                ),162            )163        }164        for (entry in body.devices) {165            if (entry.deviceId == ourDeviceId || entry.deviceId == issuer.deviceId) continue166            // Terminal: no manifest re-admits a revoked device. Matched on the167            // key as well as the id, because the id is the issuer's to choose —168            // checking only the id let a revoked key walk back in under a fresh169            // one. The check sits ahead of the existing-device lookup so it also170            // refuses rotating a device we still trust onto a revoked key.171            if (registry.isRevoked(entry.deviceId, entry.longTermPublicKeyHex)) continue172            val existing = registry.get(entry.deviceId)173            if (existing == null) {174                pending.upsert(175                    PendingVouchedDevice(176                        deviceId = entry.deviceId,177                        deviceName = entry.deviceName,178                        deviceType = entry.deviceType,179                        longTermPublicKeyHex = entry.longTermPublicKeyHex.lowercase(),180                        signingPublicKeyHex = entry.signingPublicKeyHex.lowercase(),181                        wsPort = entry.wsPort,182                        pairedAt = entry.pairedAt,183                        receivedAt = System.currentTimeMillis(),184                        vouchedByDeviceId = issuer.deviceId,185                    ),186                )187            } else {188                deviceKeyRotationAlert(existing, entry, System.currentTimeMillis())?.let { alert ->189                    syncAlerts?.record(listOf(alert))190                }191                // S5: keys and ports propagate through the mesh, the name does192                // not. A device names itself at pairing; letting a third-party193                // issuer rewrite that is the rename-then-impersonate vector.194                registry.upsert(195                    existing.copy(196                        deviceName = existing.deviceName?.takeIf { it.isNotBlank() }197                            ?: entry.deviceName,198                        deviceType = entry.deviceType,199                        longTermPublicKeyHex = entry.longTermPublicKeyHex.lowercase(),200                        signingPublicKeyHex = entry.signingPublicKeyHex.lowercase(),201                        wsPort = existing.wsPort ?: entry.wsPort,202                        pairedAt = existing.pairedAt,203                        trustSource = existing.trustSource ?: "direct",204                    ),205                )206            }207        }208    }209210    private fun requireMasterKey(): ByteArray =211        repo.syncMasterKey() ?: throw VaultLockedException()212213    private fun deriveEntryKey(masterKey: ByteArray, entryId: String): ByteArray {214        // Null-byte separator (HKDF hardening): entryId cannot contain U+0000, so215        // the (entryId, suffix) boundary is unambiguous regardless of future id216        // formats. Coordinated wire change — peach-browser deriveEntryKey produces217        // the identical info bytes; the two MUST stay byte-for-byte in lockstep.218        val info = (entryId + "\u0000" + ENTRY_KEY_INFO_SUFFIX).toByteArray(Charsets.UTF_8)219        val gen = HKDFBytesGenerator(SHA256Digest())220        gen.init(HKDFParameters(masterKey, ByteArray(0), info))221        return ByteArray(32).also { gen.generateBytes(it, 0, it.size) }222    }223224    private fun encryptEntry(key: ByteArray, entry: VaultEntry): String {225        val plaintext = entryJson.encodeToString(VaultEntry.serializer(), entry).toByteArray(Charsets.UTF_8)226        val nonce = ByteArray(12).also(rng::nextBytes)227        val cipher = Cipher.getInstance("AES/GCM/NoPadding")228        cipher.init(Cipher.ENCRYPT_MODE, SecretKeySpec(key, "AES"), GCMParameterSpec(128, nonce))229        cipher.updateAAD(ENTRY_AAD)230        val ct = cipher.doFinal(plaintext)231        return b64(nonce + ct)232    }233234    private fun decryptEntryOrNull(key: ByteArray, envelopeB64: String): VaultEntry? = try {235        val bytes = unb64(envelopeB64)236        if (bytes.size < 12 + 16) null else {237            val nonce = bytes.copyOfRange(0, 12)238            val ct = bytes.copyOfRange(12, bytes.size)239            val cipher = Cipher.getInstance("AES/GCM/NoPadding")240            cipher.init(Cipher.DECRYPT_MODE, SecretKeySpec(key, "AES"), GCMParameterSpec(128, nonce))241            cipher.updateAAD(ENTRY_AAD)242            val pt = cipher.doFinal(ct)243            entryJson.decodeFromString(VaultEntry.serializer(), String(pt, Charsets.UTF_8))244        }245    } catch (_: Exception) {246        null247    }248249    private companion object {250        const val ENTRY_KEY_INFO_SUFFIX = "sync-entry-v1"251        val ENTRY_AAD = "peach-sync-entry-v1".toByteArray(Charsets.UTF_8)252        val rng = SecureRandom()253        val entryJson = Json { encodeDefaults = false; ignoreUnknownKeys = true }254        fun b64(b: ByteArray): String = Base64.getEncoder().encodeToString(b)255        fun unb64(s: String): ByteArray = Base64.getDecoder().decode(s)256    }257}258259class VaultLockedException : Exception("vault_locked")