fix(attestation): correct module_hash to match AOSP Keystore2
BouncyCastle DERSet() sorts by full encoded sequence, but AOSP keystore2 maintenance.rs sorts by encoded name only. Replace PackageManager-based APEX enumeration with filesystem scan of /apex/ directories using a minimal protobuf parser for apex_manifest.pb. Encode the DER SET tag manually to preserve the name-only sort order.
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@@ -1,9 +1,11 @@
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package org.matrix.TEESimulator.util
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import android.content.pm.PackageManager
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import android.hardware.security.keymint.SecurityLevel
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import android.os.Build
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import android.os.SystemProperties
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import java.io.ByteArrayOutputStream
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import java.io.File
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import java.io.FileInputStream
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import java.security.MessageDigest
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import java.time.LocalDate
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import java.util.concurrent.ThreadLocalRandom
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@@ -11,7 +13,6 @@ import org.bouncycastle.asn1.ASN1EncodableVector
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import org.bouncycastle.asn1.ASN1Integer
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import org.bouncycastle.asn1.DEROctetString
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import org.bouncycastle.asn1.DERSequence
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import org.bouncycastle.asn1.DERSet
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import org.matrix.TEESimulator.attestation.DeviceAttestationService
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import org.matrix.TEESimulator.config.ConfigurationManager
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import org.matrix.TEESimulator.logging.SystemLogger
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@@ -371,52 +372,174 @@ object AndroidDeviceUtils {
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// --- APEX and Module Hash Properties ---
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private val apexInfos: List<Pair<String, Long>> by lazy {
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runCatching {
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val pm = ConfigurationManager.getPackageManager()
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val packages =
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if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.TIRAMISU) {
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pm?.getInstalledPackages(PackageManager.MATCH_APEX.toLong(), 0)
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} else {
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@Suppress("DEPRECATION")
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pm?.getInstalledPackages(PackageManager.MATCH_APEX, 0)
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// Minimal protobuf parser for apex_manifest.pb (field 1: name, field 2: version)
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private class MinimalApexManifestParser(private val data: ByteArray) {
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var pos = 0
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fun parse(): Pair<String, Long>? {
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var name: String? = null
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var version: Long? = null
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while (pos < data.size) {
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val tag = readVarint()
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val fieldNum = tag ushr 3
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val wireType = (tag and 0x07).toInt()
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when (fieldNum) {
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1L -> {
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val length = readVarint().toInt()
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if (pos + length > data.size) return null
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name = String(data, pos, length, Charsets.UTF_8)
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pos += length
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}
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packages?.list.orEmpty().map { it.packageName to it.longVersionCode }
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2L -> {
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version = readVarint()
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}
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else -> skipField(wireType)
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}
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}
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.getOrElse {
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SystemLogger.error("Failed to get APEX package information.", it)
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emptyList()
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return if (name != null && version != null) {
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name to version
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} else {
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null
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}
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}
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private fun readVarint(): Long {
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var value = 0L
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var shift = 0
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while (pos < data.size) {
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val b = data[pos++].toInt()
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value = value or ((b and 0x7F).toLong() shl shift)
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if ((b and 0x80) == 0) return value
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shift += 7
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}
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return value
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}
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private fun skipField(wireType: Int) {
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when (wireType) {
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0 -> readVarint()
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1 -> pos += 8
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2 -> {
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val len = readVarint().toInt()
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pos += len
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}
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5 -> pos += 4
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else -> throw IllegalStateException("Unknown wire type $wireType")
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}
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}
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}
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private val apexInfos: List<Pair<String, Long>> by lazy {
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val results = mutableListOf<Pair<String, Long>>()
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val apexRoot = File("/apex")
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if (!apexRoot.exists() || !apexRoot.isDirectory) {
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return@lazy emptyList()
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}
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apexRoot.listFiles()?.forEach { file ->
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if (!file.isDirectory) return@forEach
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val name = file.name
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if (name.startsWith(".")) return@forEach
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if (name.contains("@")) return@forEach
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if (name == "sharedlibs") return@forEach
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val manifestFile = File(file, "apex_manifest.pb")
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if (manifestFile.exists()) {
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runCatching {
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val bytes = FileInputStream(manifestFile).use { it.readBytes() }
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val parser = MinimalApexManifestParser(bytes)
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parser.parse()?.let { (pkgName, version) -> results.add(pkgName to version) }
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}
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}
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}
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results.distinctBy { it.first }
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}
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val moduleHash: ByteArray by lazy {
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DeviceAttestationService.CachedAttestationData?.moduleHash
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?: runCatching {
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// TODO: figure out the correct calculation
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val moduleSequences = ASN1EncodableVector()
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data class ModuleEntry(
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val nameEncoded: ByteArray,
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val fullEncoded: ByteArray,
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)
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// 1. Create a DERSequence for each module.
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apexInfos.forEach { (packageName, versionCode) ->
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val moduleVector = ASN1EncodableVector()
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// Use explicit UTF-8 encoding for the package name.
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moduleVector.add(DEROctetString(packageName.toByteArray(Charsets.UTF_8)))
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moduleVector.add(ASN1Integer(versionCode))
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moduleSequences.add(DERSequence(moduleVector))
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}
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val modules =
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apexInfos.map { (packageName, versionCode) ->
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val nameOctet = DEROctetString(packageName.toByteArray(Charsets.UTF_8))
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val versionInt = ASN1Integer(versionCode)
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// 2. Create a DERSet. Bouncy Castle will automatically handle
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// the sorting based on the DER-encoded value of each sequence.
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val modulesSet = DERSet(moduleSequences)
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val vec = ASN1EncodableVector()
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vec.add(nameOctet)
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vec.add(versionInt)
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val sequence = DERSequence(vec)
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// 3. Get the final DER-encoded byte array of the SET.
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val encodedModules = modulesSet.encoded
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// AOSP sorts by encoded name only, not full sequence
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ModuleEntry(
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nameEncoded = nameOctet.encoded,
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fullEncoded = sequence.encoded,
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)
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}
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// 4. Compute the SHA-256 hash.
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MessageDigest.getInstance("SHA-256").digest(encodedModules)
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val sortedModules =
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modules.sortedWith { m1, m2 ->
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compareByteArrays(m1.nameEncoded, m2.nameEncoded)
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}
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val payloadStream = ByteArrayOutputStream()
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sortedModules.forEach { payloadStream.write(it.fullEncoded) }
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val payload = payloadStream.toByteArray()
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// Wrap in DER SET tag manually — DERSet() re-sorts by full encoding
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val finalDerSet = encodeAsDerSet(payload)
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MessageDigest.getInstance("SHA-256").digest(finalDerSet)
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}
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.getOrElse {
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SystemLogger.error("Failed to compute module hash.", it)
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ByteArray(32) // Return empty hash on failure
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ByteArray(32)
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}
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}
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private fun compareByteArrays(a: ByteArray, b: ByteArray): Int {
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val length = minOf(a.size, b.size)
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for (i in 0 until length) {
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val byteA = a[i].toInt() and 0xFF
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val byteB = b[i].toInt() and 0xFF
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if (byteA != byteB) {
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return byteA - byteB
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}
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}
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return a.size - b.size
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}
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private fun encodeAsDerSet(payload: ByteArray): ByteArray {
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val out = ByteArrayOutputStream()
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out.write(0x31)
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writeDerLength(out, payload.size)
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out.write(payload)
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return out.toByteArray()
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}
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private fun writeDerLength(out: ByteArrayOutputStream, length: Int) {
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if (length < 128) {
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out.write(length)
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} else {
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var size = length
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val bytes = ArrayList<Byte>()
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while (size > 0) {
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bytes.add((size and 0xFF).toByte())
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size = size ushr 8
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}
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out.write(0x80 or bytes.size)
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for (i in bytes.indices.reversed()) {
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out.write(bytes[i].toInt())
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}
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}
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}
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}
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