DeviceManifestSupport.kt

1package com.peachpasswords.sync23import kotlinx.serialization.builtins.serializer4import kotlinx.serialization.json.Json5import org.bouncycastle.crypto.params.Ed25519PrivateKeyParameters67/** 0x03 adds relay routing to each introduced peer edge. */8const val DEVICE_MANIFEST_VERSION = 0x039private const val DEVICE_MANIFEST_FRESHNESS_MS = 5 * 60_000L10/**11 * Upper bounds on what verifyDeviceManifest will accept. A pathological peer12 * could otherwise craft a manifest that consumes unbounded memory or skips13 * sanity checks (e.g. `issuedAt = Long.MIN_VALUE` bypasses `abs(...) > window`14 * because `abs(Long.MIN_VALUE)` is still negative). These caps match the15 * realistic limits of the pairing protocol: a handful of paired devices, a16 * bounded revocation list, and string fields long enough for any honest use.17 */18private const val MAX_MANIFEST_DEVICES = 25619private const val MAX_MANIFEST_REVOCATIONS = 50020private const val MAX_MANIFEST_STRING = 25621internal const val NO_KEY_SENTINEL = "0000000000000000000000000000000000000000000000000000000000000000"2223/**24 * Fully staged membership change. Implementations must linearize the whole25 * batch; callers hold the vault session epoch fence while invoking it, so a26 * lock/re-unlock cannot observe or leave behind a half-applied manifest.27 */28data class DeviceManifestRegistryBatch(29    val incomingRevocations: List<DeviceRevocation>,30    val removals: Set<String>,31    val upserts: List<PairedDevice>,32)3334interface PairedDeviceRegistry {35    fun getAll(): List<PairedDevice>36    fun get(id: String): PairedDevice?37    fun getByPubkey(pubkeyHex: String): PairedDevice? =38        getAll().firstOrNull {39            it.longTermPublicKeyHex?.let { key -> CryptoCompare.hex(key, pubkeyHex) } == true40        }41    fun upsert(device: PairedDevice)42    fun remove(deviceId: String) {}43    fun listRevocations(): List<DeviceRevocation> = emptyList()4445    /** Commit a complete staged manifest as one logical registry mutation. */46    fun applyManifestBatch(batch: DeviceManifestRegistryBatch): Boolean4748    /** Returns the ids that were not already revoked. */49    fun mergeRevocations(incoming: List<DeviceRevocation>): List<String> = emptyList()5051    /**52     * True when either the id or the long-term key is under a terminal53     * revocation. `deviceId` is a self-asserted string in a manifest, so54     * keying terminality on it alone is bypassed by re-vouching a revoked55     * device's key under a fresh id. The key is what a revoked device still56     * holds, so it is what terminality has to follow. `0`×64 is the "no key was57     * ever stored" sentinel (see PairedDeviceStore.revoke) and matches nothing.58     */59    fun isRevoked(deviceId: String, longTermPublicKeyHex: String? = null): Boolean {60        val key = longTermPublicKeyHex?.lowercase()?.takeIf { it != NO_KEY_SENTINEL }61        return listRevocations().any {62            it.deviceId == deviceId || (key != null && it.longTermPublicKeyHex.lowercase() == key)63        }64    }6566    /** Only a direct, SAS-confirmed re-pair may lift a terminal revocation. */67    fun clearRevocation(deviceId: String) {}68}6970fun buildSignedDeviceManifest(71    issuerDeviceId: String,72    devices: List<ManifestDeviceEntry>,73    signingPrivateKey: Ed25519PrivateKeyParameters,74    nowMs: Long = System.currentTimeMillis(),75    revoked: List<DeviceRevocation> = emptyList(),76): SignedDeviceManifest {77    require(issuerDeviceId.isNotBlank()) { "issuerDeviceId is required" }78    val body = DeviceManifestBody(79        manifestVersion = DEVICE_MANIFEST_VERSION,80        issuerDeviceId = issuerDeviceId,81        issuedAt = nowMs,82        // Normalise valid entries but keep invalid ones too — verifyDeviceManifest83        // is the gate that detects malformed input (M-09: silent drop would let84        // a caller believe they sent a valid manifest).85        devices = devices.map { normaliseManifestEntry(it) ?: it },86        revoked = revoked.map(::normaliseRevocation),87    )88    val signature = signEd25519(signingPrivateKey, canonicalDeviceManifestBody(body).toByteArray(Charsets.UTF_8))89    return SignedDeviceManifest(body, pubkeyToHex(signature))90}9192fun verifyDeviceManifest(93    manifest: SignedDeviceManifest,94    issuerSigningPublicKey: ByteArray,95    nowMs: Long = System.currentTimeMillis(),96    freshnessMs: Long = DEVICE_MANIFEST_FRESHNESS_MS,97): DeviceManifestBody? {98    val body = manifest.body99    if (body.manifestVersion != DEVICE_MANIFEST_VERSION) return null100    // Two-sided bounds — avoids `abs(...) > window`, which overflows for101    // `Long.MIN_VALUE` and lets a peer-presented timestamp bypass the102    // freshness gate. Reject negative `issuedAt` outright so the bounds103    // arithmetic can't be steered into a wrap-around by the manifest.104    if (body.issuedAt < 0L) return null105    if (body.issuedAt < nowMs - freshnessMs || body.issuedAt > nowMs + freshnessMs) return null106    if (body.issuerDeviceId.isBlank() || body.issuerDeviceId.length > MAX_MANIFEST_STRING) return null107    if (body.devices.size > MAX_MANIFEST_DEVICES) return null108    if (body.revoked.size > MAX_MANIFEST_REVOCATIONS) return null109    if (!isHex(manifest.signatureHex, 128)) return null110    if (!body.devices.all { normaliseManifestEntry(it) != null }) return null111    if (!body.revoked.all { isValidRevocation(it) }) return null112    val signature = runCatching { hexToBytes(manifest.signatureHex) }.getOrNull() ?: return null113    val canonical = canonicalDeviceManifestBody(body).toByteArray(Charsets.UTF_8)114    if (!verifyEd25519(issuerSigningPublicKey, canonical, signature)) return null115    return body116}117118fun canonicalDeviceManifestBody(body: DeviceManifestBody): String =119    canonicalise(120        mapOf(121            "devices" to body.devices.map { manifestEntryMap(it) },122            "issuedAt" to body.issuedAt,123            "issuerDeviceId" to body.issuerDeviceId,124            "manifestVersion" to body.manifestVersion,125            "revoked" to body.revoked.map { revocationMap(it) },126        ),127    )128129fun PairedDevice.toManifestEntry(): ManifestDeviceEntry? {130    val id = deviceId.takeIf { it.isNotBlank() } ?: return null131    val name = deviceName?.takeIf { it.isNotBlank() } ?: return null132    val type = deviceType?.takeIf { it in setOf("extension", "android", "ios") } ?: return null133    val longTerm = longTermPublicKeyHex?.lowercase()?.takeIf { isHex(it, 64) } ?: return null134    val signing = signingPublicKeyHex?.lowercase()?.takeIf { isHex(it, 64) } ?: return null135    return ManifestDeviceEntry(136        deviceId = id,137        deviceName = name,138        deviceType = type,139        longTermPublicKeyHex = longTerm,140        signingPublicKeyHex = signing,141        wsPort = wsPort,142        relayUrl = relayUrl,143        pairedAt = pairedAt,144    )145}146147private fun normaliseManifestEntry(entry: ManifestDeviceEntry): ManifestDeviceEntry? {148    if (entry.deviceId.isBlank() || entry.deviceName.isBlank()) return null149    // Bound string fields — a peer could otherwise send multi-megabyte strings150    // that pass the format checks and bloat the canonical signature input.151    if (entry.deviceId.length > MAX_MANIFEST_STRING || entry.deviceName.length > MAX_MANIFEST_STRING) return null152    if (entry.deviceType !in setOf("extension", "android", "ios")) return null153    if (!isHex(entry.longTermPublicKeyHex, 64) || !isHex(entry.signingPublicKeyHex, 64)) return null154    if (entry.wsPort != null && entry.wsPort !in 1..65_535) return null155    if (entry.pairedAt < 0L) return null156    if (157        entry.relayUrl != null && (158            entry.relayUrl.length > MAX_MANIFEST_STRING ||159            runCatching { Rendezvous.normalizeRelayUrl(entry.relayUrl) }.isFailure160        )161    ) return null162    return entry.copy(163        longTermPublicKeyHex = entry.longTermPublicKeyHex.lowercase(),164        signingPublicKeyHex = entry.signingPublicKeyHex.lowercase(),165    )166}167168private fun normaliseRevocation(r: DeviceRevocation): DeviceRevocation =169    r.copy(longTermPublicKeyHex = r.longTermPublicKeyHex.lowercase())170171private fun isValidRevocation(r: DeviceRevocation): Boolean =172    r.deviceId.isNotBlank() && r.deviceId.length <= MAX_MANIFEST_STRING &&173        isHex(r.longTermPublicKeyHex.lowercase(), 64) &&174        r.revokedByDeviceId.isNotBlank() && r.revokedByDeviceId.length <= MAX_MANIFEST_STRING &&175        r.revokedAt >= 0L176177private fun revocationMap(r: DeviceRevocation): Map<String, Any> = linkedMapOf(178    "deviceId" to r.deviceId,179    "longTermPublicKeyHex" to r.longTermPublicKeyHex.lowercase(),180    "revokedAt" to r.revokedAt,181    "revokedByDeviceId" to r.revokedByDeviceId,182)183184private fun manifestEntryMap(entry: ManifestDeviceEntry): Map<String, Any> {185    val normalised = normaliseManifestEntry(entry) ?: entry186    val map = linkedMapOf<String, Any>(187        "deviceId" to normalised.deviceId,188        "deviceName" to normalised.deviceName,189        "deviceType" to normalised.deviceType,190        "longTermPublicKeyHex" to normalised.longTermPublicKeyHex.lowercase(),191        "pairedAt" to normalised.pairedAt,192        "signingPublicKeyHex" to normalised.signingPublicKeyHex.lowercase(),193    )194    normalised.wsPort?.let { map["wsPort"] = it }195    normalised.relayUrl?.let { map["relayUrl"] = it }196    return map197}198199private fun canonicalise(value: Any?): String = when (value) {200    null -> "null"201    is Number -> {202        val d = value.toDouble()203        require(d.isFinite()) { "non-finite number" }204        if (d % 1.0 == 0.0) value.toLong().toString() else value.toString()205    }206    is String -> Json.encodeToString(String.serializer(), value)207    is Boolean -> if (value) "true" else "false"208    is List<*> -> value.joinToString(prefix = "[", postfix = "]", separator = ",") { canonicalise(it) }209    is Map<*, *> -> value.entries210        .map { (k, v) -> k.toString() to v }211        .sortedBy { it.first }212        .joinToString(prefix = "{", postfix = "}", separator = ",") { (k, v) ->213            Json.encodeToString(String.serializer(), k) + ":" + canonicalise(v)214        }215    else -> error("cannot canonicalise ${value::class.simpleName}")216}217218private fun isHex(value: String, length: Int): Boolean =219    value.length == length && value.all { it in '0'..'9' || it in 'a'..'f' }