feat(pki): integrate native cert gen with BouncyCastle fallback

NativeCertGen.kt provides CertGenConfig data class and JNI bridge to libcertgen.so. KeyMintSecurityLevelInterceptor.doSoftwareKeyGen() tries native path first, falls back to BouncyCastle on failure or when library unavailable. App.kt loads libcertgen.so at daemon start.
2026-03-09 16:23:09 +01:00
parent c87759c6c3
commit ac9641ed2a
4 changed files with 194 additions and 4 deletions
@@ -13,6 +13,7 @@ import org.matrix.TEESimulator.interception.keystore.AbstractKeystoreInterceptor
 import org.matrix.TEESimulator.interception.keystore.Keystore2Interceptor
 import org.matrix.TEESimulator.interception.keystore.KeystoreInterceptor
 import org.matrix.TEESimulator.logging.SystemLogger
+import org.matrix.TEESimulator.pki.NativeCertGen
 import org.matrix.TEESimulator.util.AndroidDeviceUtils

 /**
@@ -51,6 +52,8 @@ object App {
            Security.removeProvider(BouncyCastleProvider.PROVIDER_NAME)
            Security.addProvider(BouncyCastleProvider())

+            NativeCertGen.initialize("/data/adb/modules/tricky_store/libcertgen.so")
+
            // This starts the message queue processing. It blocks here indefinitely
            // processing messages until Looper.myLooper().quit() is called.
            Looper.loop()
@@ -345,7 +345,7 @@ object AttestationBuilder {
     *   retrieved.
     */
    @Throws(Throwable::class)
-    private fun createApplicationId(uid: Int): DEROctetString {
+    internal fun createApplicationId(uid: Int): DEROctetString {
        val pm =
            ConfigurationManager.getPackageManager()
                ?: throw IllegalStateException("PackageManager not found!")
@@ -8,6 +8,7 @@ import android.hardware.security.keymint.Tag
 import android.os.IBinder
 import android.os.Parcel
 import android.system.keystore2.*
+import android.util.Pair as AndroidPair
 import java.io.ByteArrayInputStream
 import java.security.KeyFactory
 import java.security.KeyPair
@@ -17,6 +18,7 @@ import java.security.cert.CertificateFactory
 import java.security.spec.PKCS8EncodedKeySpec
 import java.util.concurrent.ConcurrentHashMap
 import java.util.concurrent.atomic.AtomicInteger
+import org.matrix.TEESimulator.attestation.AttestationBuilder
 import org.matrix.TEESimulator.attestation.AttestationPatcher
 import org.matrix.TEESimulator.attestation.KeyMintAttestation
 import org.matrix.TEESimulator.config.ConfigurationManager
@@ -24,8 +26,12 @@ import org.matrix.TEESimulator.interception.core.BinderInterceptor
 import org.matrix.TEESimulator.interception.keystore.InterceptorUtils
 import org.matrix.TEESimulator.interception.keystore.KeyIdentifier
 import org.matrix.TEESimulator.logging.SystemLogger
+import org.matrix.TEESimulator.pki.CertGenConfig
 import org.matrix.TEESimulator.pki.CertificateGenerator
 import org.matrix.TEESimulator.pki.CertificateHelper
+import org.matrix.TEESimulator.pki.KeyBoxManager
+import org.matrix.TEESimulator.pki.NativeCertGen
+import org.matrix.TEESimulator.util.AndroidDeviceUtils

 class KeyMintSecurityLevelInterceptor(
    private val original: IKeystoreSecurityLevel,
@@ -296,9 +302,16 @@ class KeyMintSecurityLevelInterceptor(
        keyDescriptor.nspace = secureRandom.nextLong()
        SystemLogger.info("Generating software key for ${keyDescriptor.alias}[${keyDescriptor.nspace}].")

-        val keyData = CertificateGenerator.generateAttestedKeyPair(
-            callingUid, keyDescriptor.alias, attestationKey?.alias, parsedParams, securityLevel,
-        ) ?: throw Exception("CertificateGenerator failed to create key pair.")
+        val keyData = if (NativeCertGen.isAvailable && attestationKey == null) {
+            generateAttestedKeyPairNative(callingUid, parsedParams)
+                ?: CertificateGenerator.generateAttestedKeyPair(
+                    callingUid, keyDescriptor.alias, attestationKey?.alias, parsedParams, securityLevel,
+                )
+        } else {
+            CertificateGenerator.generateAttestedKeyPair(
+                callingUid, keyDescriptor.alias, attestationKey?.alias, parsedParams, securityLevel,
+            )
+        } ?: throw Exception("Both native and BouncyCastle cert gen failed.")

        cleanupKeyData(keyId)
        val response = buildKeyEntryResponse(keyData.second, parsedParams, keyDescriptor)
@@ -322,6 +335,74 @@ class KeyMintSecurityLevelInterceptor(
        return InterceptorUtils.createTypedObjectReply(response.metadata)
    }

+    private fun generateAttestedKeyPairNative(
+        callingUid: Int,
+        params: KeyMintAttestation,
+    ): AndroidPair<KeyPair, List<Certificate>>? {
+        return runCatching {
+            val algorithmName = when (params.algorithm) {
+                Algorithm.EC -> "EC"
+                Algorithm.RSA -> "RSA"
+                else -> return null
+            }
+            val keyboxFile = ConfigurationManager.getKeyboxFileForUid(callingUid)
+            val keybox = KeyBoxManager.getAttestationKey(keyboxFile, algorithmName) ?: return null
+
+            val keyboxPrivateKeyBytes = keybox.keyPair.private.encoded
+            val keyboxCertChainBytes = keybox.certificates
+                .map { it.encoded }
+                .fold(ByteArray(0)) { acc, der -> acc + der }
+
+            val attestVersion = AndroidDeviceUtils.getAttestVersion(securityLevel)
+            val keymasterVersion = AndroidDeviceUtils.getKeymasterVersion(securityLevel)
+            val appId = AttestationBuilder.createApplicationId(callingUid)
+
+            val config = CertGenConfig(
+                algorithm = params.algorithm,
+                keySize = params.keySize,
+                ecCurve = params.ecCurve,
+                rsaPublicExponent = params.rsaPublicExponent?.toLong() ?: 65537L,
+                attestationChallenge = params.attestationChallenge,
+                purposes = params.purpose.toIntArray(),
+                digests = params.digest.toIntArray(),
+                certSerial = params.certificateSerial?.toByteArray(),
+                certSubject = params.certificateSubject?.encoded,
+                certNotBefore = params.certificateNotBefore?.time ?: -1L,
+                certNotAfter = params.certificateNotAfter?.time ?: -1L,
+                keyboxPrivateKey = keyboxPrivateKeyBytes,
+                keyboxCertChain = keyboxCertChainBytes,
+                securityLevel = securityLevel,
+                attestVersion = attestVersion,
+                keymasterVersion = keymasterVersion,
+                osVersion = AndroidDeviceUtils.osVersion,
+                osPatchLevel = AndroidDeviceUtils.getPatchLevel(callingUid),
+                vendorPatchLevel = AndroidDeviceUtils.getVendorPatchLevelLong(callingUid),
+                bootPatchLevel = AndroidDeviceUtils.getBootPatchLevelLong(callingUid),
+                bootKey = AndroidDeviceUtils.bootKey,
+                bootHash = AndroidDeviceUtils.bootHash,
+                creationDatetime = System.currentTimeMillis(),
+                attestationApplicationId = appId.octets,
+                moduleHash = if (attestVersion >= 400) AndroidDeviceUtils.moduleHash else null,
+                idBrand = params.brand,
+                idDevice = params.device,
+                idProduct = params.product,
+                idSerial = params.serial,
+                idImei = params.imei,
+                idMeid = params.meid,
+                idManufacturer = params.manufacturer,
+                idModel = params.model,
+                idSecondImei = if (attestVersion >= 300) params.secondImei else null,
+            )
+
+            val resultBytes = NativeCertGen.generateAttestedKeyPair(config) ?: return null
+            val (keyPair, certs) = NativeCertGen.parseNativeResult(resultBytes)
+            SystemLogger.info("NativeCertGen: generated key pair successfully (${certs.size} certs)")
+            AndroidPair(keyPair, certs)
+        }.onFailure {
+            SystemLogger.error("NativeCertGen: generation failed, falling back to BouncyCastle", it)
+        }.getOrNull()
+    }
+
    private fun buildKeyEntryResponse(
        chain: List<Certificate>,
        params: KeyMintAttestation,
@@ -0,0 +1,106 @@
+package org.matrix.TEESimulator.pki
+
+import java.io.ByteArrayInputStream
+import java.nio.ByteBuffer
+import java.nio.ByteOrder
+import java.security.KeyFactory
+import java.security.KeyPair
+import java.security.cert.Certificate
+import java.security.cert.CertificateFactory
+import java.security.spec.PKCS8EncodedKeySpec
+import org.matrix.TEESimulator.logging.SystemLogger
+
+data class CertGenConfig(
+    val algorithm: Int,
+    val keySize: Int,
+    val ecCurve: Int,
+    val rsaPublicExponent: Long,
+    val attestationChallenge: ByteArray?,
+    val purposes: IntArray,
+    val digests: IntArray,
+    val certSerial: ByteArray?,
+    val certSubject: ByteArray?,
+    val certNotBefore: Long,
+    val certNotAfter: Long,
+    val keyboxPrivateKey: ByteArray,
+    val keyboxCertChain: ByteArray,
+    val securityLevel: Int,
+    val attestVersion: Int,
+    val keymasterVersion: Int,
+    val osVersion: Int,
+    val osPatchLevel: Int,
+    val vendorPatchLevel: Int,
+    val bootPatchLevel: Int,
+    val bootKey: ByteArray,
+    val bootHash: ByteArray,
+    val creationDatetime: Long,
+    val attestationApplicationId: ByteArray,
+    val moduleHash: ByteArray?,
+    val idBrand: ByteArray?,
+    val idDevice: ByteArray?,
+    val idProduct: ByteArray?,
+    val idSerial: ByteArray?,
+    val idImei: ByteArray?,
+    val idMeid: ByteArray?,
+    val idManufacturer: ByteArray?,
+    val idModel: ByteArray?,
+    val idSecondImei: ByteArray?,
+)
+
+object NativeCertGen {
+
+    @Volatile
+    var isAvailable: Boolean = false
+        private set
+
+    fun initialize(libraryPath: String) {
+        try {
+            System.load(libraryPath)
+            isAvailable = true
+            SystemLogger.info("NativeCertGen: loaded libcertgen.so successfully")
+        } catch (e: UnsatisfiedLinkError) {
+            SystemLogger.error("NativeCertGen: failed to load libcertgen.so, falling back to BouncyCastle", e)
+        }
+    }
+
+    external fun generateAttestedKeyPair(config: CertGenConfig): ByteArray?
+
+    external fun generateSoftwareKeyPair(
+        algorithm: Int,
+        keySize: Int,
+        ecCurve: Int,
+        rsaPublicExponent: Long,
+    ): ByteArray?
+
+    external fun initLogging(verbose: Boolean)
+
+    external fun dumpLogs(): String
+
+    fun parseNativeResult(bytes: ByteArray): Pair<KeyPair, List<Certificate>> {
+        val buf = ByteBuffer.wrap(bytes).order(ByteOrder.BIG_ENDIAN)
+
+        val pkLen = buf.getInt()
+        val pkBytes = ByteArray(pkLen)
+        buf.get(pkBytes)
+
+        val numCerts = buf.getInt()
+        val certs = mutableListOf<Certificate>()
+        val certFactory = CertificateFactory.getInstance("X.509")
+        repeat(numCerts) {
+            val certLen = buf.getInt()
+            val certBytes = ByteArray(certLen)
+            buf.get(certBytes)
+            certs.add(certFactory.generateCertificate(ByteArrayInputStream(certBytes)))
+        }
+
+        val algorithmName = when (certs[0].publicKey.algorithm) {
+            "EC" -> "EC"
+            "RSA" -> "RSA"
+            else -> certs[0].publicKey.algorithm
+        }
+        val keyFactory = KeyFactory.getInstance(algorithmName)
+        val privateKey = keyFactory.generatePrivate(PKCS8EncodedKeySpec(pkBytes))
+        val publicKey = certs[0].publicKey
+        return Pair(KeyPair(publicKey, privateKey), certs)
+    }
+}