java: Overhaul detection of attestation properties

- Reuse and extend the attestation we perform for detection of functional TEE.
- Extract properties like boot hash, os version, attest version, keymaster version from the generated certificate.
- Use previous methods as fallback for devices without functional TEE.
- Set ro.boot.vbmeta.digest during initialization with the boot hash value.

Signed-off-by: Dakkshesh <beakthoven@gmail.com>

app/src/main/java/io/github/beakthoven/TrickyStoreOSS/AndroidUtils.kt

@@ -23,20 +23,61 @@ fun getTransactCode(clazz: Class<*>, method: String): Int =
     clazz.getDeclaredField("TRANSACTION_$method").apply { isAccessible = true }
         .getInt(null)
 
-val bootHash: ByteArray by lazy {
+// cache attest data to avoid running attestation multiple times
-    getBootHashFromProp() ?: randomBytes()
+private val cachedAttestData: AttestationData? by lazy {
+    getAttestData() // from CertHacker
 }
 
 val bootKey: ByteArray by lazy {
     randomBytes()
 }
 
+fun setupBootHash() {
+    getBootHashFromProp()?.also { 
+        Logger.d("Using boot hash from system property: ${it.toHex()}")
+    }
+    ?: getBootHashFromAttestation()?.also { 
+        Logger.d("Using boot hash from attestation: ${it.toHex()}")
+        setBootHashProp(it)
+    }
+    ?: randomBytes().also { 
+        Logger.d("Generating random boot hash: ${it.toHex()}")
+        setBootHashProp(it)
+    }
+}
+
 @OptIn(ExperimentalStdlibApi::class)
-private fun getBootHashFromProp(): ByteArray? {
+fun getBootHashFromProp(): ByteArray? {
     val digest = SystemProperties.get("ro.boot.vbmeta.digest", null) ?: return null
+    Logger.d("System property ro.boot.vbmeta.digest: $digest")
+    
+    if (digest.isBlank()) {
+        Logger.d("Property is blank")
+        return null
+    }
+    
     return if (digest.length == 64) digest.hexToByteArray() else null
 }
 
+private fun getBootHashFromAttestation(): ByteArray? {
+    return try {
+        cachedAttestData?.verifiedBootHash
+    } catch (e: Exception) {
+        Logger.e("Failed to get boot hash from attestation: ${e.message}")
+        null
+    }
+}
+
+private fun setBootHashProp(bytes: ByteArray) {
+    val hex = bytes.toHex()
+    try {
+        Logger.d("Setting ro.boot.vbmeta.digest to: $hex")
+        SystemProperties.set("ro.boot.vbmeta.digest", hex)
+    } catch (e: Exception) {
+        Logger.e("Exception setting vbmeta digest: ${e.message}")
+    }
+}
+
 private fun randomBytes(): ByteArray = ByteArray(32).also { 
     ThreadLocalRandom.current().nextBytes(it) 
 }
@@ -114,9 +155,6 @@ private fun parsePatchLevelValue(value: String, component: String, isLong: Boole
     }
 }
 
-val osVersion: Int
-    get() = getOsVersion(Build.VERSION.SDK_INT)
-
 private val osVersionMap = mapOf(
     Build.VERSION_CODES.BAKLAVA to 160000,
     Build.VERSION_CODES.VANILLA_ICE_CREAM to 150000,
@@ -128,7 +166,8 @@ private val osVersionMap = mapOf(
     Build.VERSION_CODES.Q to 100000
 )
 
-private fun getOsVersion(sdkVersion: Int): Int = osVersionMap[sdkVersion] ?: 160000
+val osVersion: Int
+    get() = cachedAttestData?.osVersion ?: osVersionMap[Build.VERSION.SDK_INT] ?: 160000
 
 private val attestVersionMap = mapOf(
     Build.VERSION_CODES.Q to 4,                   // Keymaster 4.1
@@ -142,11 +181,10 @@ private val attestVersionMap = mapOf(
 )
 
 val attestVersion: Int
-    get() = attestVersionMap[Build.VERSION.SDK_INT] ?: 400
+    get() = cachedAttestData?.attestVersion ?: attestVersionMap[Build.VERSION.SDK_INT] ?: 400
 
 val keymasterVersion: Int
-    get() = if (attestVersion == 4) 41 else attestVersion
+    get() = cachedAttestData?.keymasterVersion ?: if (attestVersion == 4) 41 else attestVersion
-
 
 fun String.convertPatchLevel(isLong: Boolean): Int = runCatching {
     val parts = split("-")
@@ -195,4 +233,5 @@ val moduleHash: ByteArray by lazy {
     }
 }
 
-fun String.trimLine(): String = trim().split("\n").joinToString("\n") { it.trim() }
+fun String.trimLine(): String = trim().split("\n").joinToString("\n") { it.trim() }
+fun ByteArray.toHex(): String = joinToString("") { "%02x".format(it) }

app/src/main/java/io/github/beakthoven/TrickyStoreOSS/CertificateHacker.kt

@@ -10,14 +10,28 @@ import android.hardware.security.keymint.Algorithm
 import android.hardware.security.keymint.EcCurve
 import android.hardware.security.keymint.KeyParameter
 import android.hardware.security.keymint.Tag
+import android.os.Build
+import android.security.keystore.KeyGenParameterSpec
 import android.security.keystore.KeyProperties
 import android.system.keystore2.KeyDescriptor
 import android.util.Pair
-import io.github.beakthoven.TrickyStoreOSS.*
 import io.github.beakthoven.TrickyStoreOSS.core.config.Config
 import io.github.beakthoven.TrickyStoreOSS.core.logging.Logger
 import io.github.beakthoven.TrickyStoreOSS.interceptors.SecurityLevelInterceptor
-import org.bouncycastle.asn1.*
+import org.bouncycastle.asn1.ASN1Boolean
+import org.bouncycastle.asn1.ASN1Encodable
+import org.bouncycastle.asn1.ASN1EncodableVector
+import org.bouncycastle.asn1.ASN1Enumerated
+import org.bouncycastle.asn1.ASN1Integer
+import org.bouncycastle.asn1.ASN1ObjectIdentifier
+import org.bouncycastle.asn1.ASN1OctetString
+import org.bouncycastle.asn1.ASN1Sequence
+import org.bouncycastle.asn1.ASN1TaggedObject
+import org.bouncycastle.asn1.DERNull
+import org.bouncycastle.asn1.DEROctetString
+import org.bouncycastle.asn1.DERSequence
+import org.bouncycastle.asn1.DERSet
+import org.bouncycastle.asn1.DERTaggedObject
 import org.bouncycastle.asn1.x500.X500Name
 import org.bouncycastle.asn1.x509.Extension
 import org.bouncycastle.asn1.x509.KeyUsage
@@ -31,16 +45,21 @@ import org.bouncycastle.operator.jcajce.JcaContentSignerBuilder
 import java.io.ByteArrayInputStream
 import java.math.BigInteger
 import java.nio.charset.StandardCharsets
-import java.security.*
+import java.security.KeyPair
+import java.security.KeyPairGenerator
+import java.security.KeyStore
+import java.security.MessageDigest
+import java.security.SecureRandom
+import java.security.Security
 import java.security.cert.Certificate
 import java.security.cert.CertificateFactory
 import java.security.cert.X509Certificate
 import java.security.spec.ECGenParameterSpec
 import java.security.spec.RSAKeyGenParameterSpec
-import java.util.*
+import java.util.Date
+import java.util.LinkedList
 import java.util.concurrent.ConcurrentHashMap
 import javax.security.auth.x500.X500Principal
-import android.os.Build
 
 object CertificateHacker {
     
@@ -625,7 +644,7 @@ object CertificateHacker {
         }
         
         if (verifiedBootHash == null) {
-            verifiedBootHash = bootHash
+            verifiedBootHash = getBootHashFromProp()
         }
         
         val rootOfTrustElements = arrayOf(
@@ -684,7 +703,9 @@ object CertificateHacker {
     private fun createAttestationExtension(params: KeyGenParameters, uid: Int, securityLevel: Int = 1): Extension {
         try {
             val key = bootKey
-            val hash = bootHash
+            val hash = getBootHashFromProp()
+
+            Logger.d("Using boothash ${hash?.toHex() ?: 0}")
             
             val rootOfTrustEncodables = arrayOf(
                 DEROctetString(key),
@@ -834,4 +855,130 @@ object CertificateHacker {
         return DEROctetString(DERSequence(applicationIdArray).encoded)
     }
 
+}
+
+data class AttestationData(
+    val verifiedBootHash: ByteArray?,
+    val attestVersion: Int?,
+    val keymasterVersion: Int?,
+    val osVersion: Int?,
+)
+
+val keygen_alias = "tricky_store_oss_attest"
+
+val teeStatus: Boolean by lazy { isTEEWorking() }
+
+private fun isTEEWorking(): Boolean {
+    return try {
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
+            android.app.ActivityThread.initializeMainlineModules()
+        }
+
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+            android.security.keystore2.AndroidKeyStoreProvider.install()
+        } else {
+            android.security.keystore.AndroidKeyStoreProvider.install()
+        }
+
+        val keyStore = KeyStore.getInstance("AndroidKeyStore")
+        keyStore.load(null)
+
+        val keyPairGenerator = KeyPairGenerator.getInstance(
+            KeyProperties.KEY_ALGORITHM_EC, "AndroidKeyStore")
+
+        val challenge = ByteArray(16).apply {
+            SecureRandom().nextBytes(this)
+        }
+
+        val parameterSpec = KeyGenParameterSpec.Builder(
+            keygen_alias,
+            KeyProperties.PURPOSE_SIGN
+        )
+            .setAlgorithmParameterSpec(ECGenParameterSpec("secp256r1"))
+            .setDigests(KeyProperties.DIGEST_SHA256)
+            .setAttestationChallenge(challenge)
+            .setIsStrongBoxBacked(false)
+            .build()
+
+        keyPairGenerator.initialize(parameterSpec)
+        keyPairGenerator.generateKeyPair()
+
+        Logger.d("TEE check: successful")
+
+        // keyStore.deleteEntry(keygen_alias)
+        true
+    } catch (e: Exception) {
+        Logger.w("TEE check failure: ${e.message}")
+        false
+    }
+}
+
+private fun getAttestCert(): X509Certificate? {
+    return if (teeStatus) {
+        val keyStore = KeyStore.getInstance("AndroidKeyStore")
+        keyStore.load(null)
+        
+        val certChain = keyStore.getCertificateChain(keygen_alias)
+        if (certChain == null || certChain.isEmpty()) {
+            null
+        } else {
+            keyStore.deleteEntry(keygen_alias)
+            certChain[0] as X509Certificate
+        }
+    } else {
+        null
+    }
+}
+
+fun getAttestData(): AttestationData? {
+    val leaf: X509Certificate = getAttestCert() ?: return null
+    val ATTESTATION_OID = ASN1ObjectIdentifier("1.3.6.1.4.1.11129.2.1.17")
+
+    return try {
+        val leafHolder = X509CertificateHolder(leaf.encoded)
+        val ext: Extension = leafHolder.getExtension(ATTESTATION_OID) ?: run {
+            Logger.i("No attestation extension found on certificate")
+            return null
+        }
+
+        val keyDescriptionSeq = ASN1Sequence.getInstance(ext.extnValue.octets)
+        val encodables = keyDescriptionSeq.toArray()
+
+        val attestVersion = ASN1Integer.getInstance(encodables[0]).value.intValueExact()
+        val keymasterVersion = ASN1Integer.getInstance(encodables[2]).value.intValueExact()
+        var attestVerifiedBootHash: ByteArray? = null
+        var attestOSVersion: Int? = null
+
+        val teeEnforced = ASN1Sequence.getInstance(encodables[7])
+
+        teeEnforced.forEach { element ->
+            val tagged = element as ASN1TaggedObject
+            when (tagged.tagNo) {
+                704 -> { // Parse Root of Trust
+                    val rootOfTrustSeq = ASN1Sequence.getInstance(tagged.baseObject.toASN1Primitive())
+                    if (rootOfTrustSeq.size() >= 4) {
+                        attestVerifiedBootHash = ASN1OctetString.getInstance(rootOfTrustSeq.getObjectAt(3)).octets
+                    }
+                }
+                705 -> { // Parse OS Version
+                    attestOSVersion = ASN1Integer.getInstance(tagged.baseObject.toASN1Primitive()).value.intValueExact()
+                }
+            }
+        }
+
+        Logger.i("Extracted attestationVersion: $attestVersion")
+        Logger.i("Extracted keymasterVersion: $keymasterVersion")
+        Logger.i("Extracted verifiedBootHash: ${attestVerifiedBootHash?.toHex() ?: 0}")
+        Logger.i("Extracted osVersion: $attestOSVersion")
+
+        AttestationData(
+            verifiedBootHash = attestVerifiedBootHash,
+            attestVersion = attestVersion,
+            keymasterVersion = keymasterVersion,
+            osVersion = attestOSVersion
+        )
+    } catch (e: Exception) {
+        Logger.e("Failed to parse attestation data", e)
+        null
+    }
 }

app/src/main/java/io/github/beakthoven/TrickyStoreOSS/Main.kt

@@ -18,6 +18,7 @@ fun main(args: Array<String>) {
     Logger.i("Welcome to TrickyStoreOSS!")
     
     try {
+        setupBootHash()
         initializeInterceptors()
         maintainService()
     } catch (e: Exception) {

app/src/main/java/io/github/beakthoven/TrickyStoreOSS/core/config/Config.kt

@@ -6,18 +6,12 @@
 package io.github.beakthoven.TrickyStoreOSS.core.config
 
 import android.content.pm.IPackageManager
-import android.os.Build
 import android.os.FileObserver
 import android.os.ServiceManager
-import android.security.keystore.KeyGenParameterSpec
-import android.security.keystore.KeyProperties
 import io.github.beakthoven.TrickyStoreOSS.CertificateHacker
 import io.github.beakthoven.TrickyStoreOSS.core.logging.Logger
+import io.github.beakthoven.TrickyStoreOSS.teeStatus
 import java.io.File
-import java.security.KeyPairGenerator
-import java.security.KeyStore
-import java.security.SecureRandom
-import java.security.spec.ECGenParameterSpec
 
 object Config {
     private val hackPackages = mutableSetOf<String>()
@@ -74,58 +68,12 @@ object Config {
     @Volatile
     private var teeBroken: Boolean? = null
 
-    private fun isTEEWorking(): Boolean {
-        val alias = "tee_attest_test_key"
-        return try {
-
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {
-                android.app.ActivityThread.initializeMainlineModules();
-            }
-
-            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
-                android.security.keystore2.AndroidKeyStoreProvider.install();
-            } else {
-                android.security.keystore.AndroidKeyStoreProvider.install();
-            }
-
-            val keyStore = KeyStore.getInstance("AndroidKeyStore")
-            keyStore.load(null)
-
-            val keyPairGenerator = KeyPairGenerator.getInstance(
-                KeyProperties.KEY_ALGORITHM_EC, "AndroidKeyStore")
-
-            val challenge = ByteArray(16).apply {
-                SecureRandom().nextBytes(this)
-            }
-
-            val parameterSpec = KeyGenParameterSpec.Builder(
-                alias,
-                KeyProperties.PURPOSE_SIGN
-            )
-                .setAlgorithmParameterSpec(ECGenParameterSpec("secp256r1"))
-                .setDigests(KeyProperties.DIGEST_SHA256)
-                .setAttestationChallenge(challenge)
-                .setIsStrongBoxBacked(false)
-                .build()
-
-            keyPairGenerator.initialize(parameterSpec)
-            keyPairGenerator.generateKeyPair()
-
-            keyStore.deleteEntry(alias)
-            true
-        } catch (e: Exception) {
-            Logger.e("TEE check failure: ${e.message}")
-            false
-        }
-    }
-
-
     private fun storeTEEStatus(root: File) {
         val statusFile = File(root, TEE_STATUS_FILE)
-        val status = isTEEWorking()
+        teeBroken = !teeStatus
-        teeBroken = !status
         try {
-            statusFile.writeText("teeBroken=${!status}")
+            statusFile.writeText("teeBroken=${teeBroken}")
+            Logger.i("TEE status written to $statusFile: teeBroken=$teeBroken") 
         } catch (e: Exception) {
             Logger.e("Failed to write TEE status: ${e.message}")
         }

stub/src/main/java/android/os/SystemProperties.java

@@ -9,4 +9,8 @@ public class SystemProperties {
     public static String get(String key, String def) {
         throw new RuntimeException("");
     }
+
+    public static void set(String key, String val) {
+        throw new RuntimeException("");
+    }
 }