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bmartybmarty
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Expose service to let Element X access some internal data
Note: Using permission "${applicationId}.READ_DATA" with android:protectionLevel="normal" does not work in release mode.
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4 files changed

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‎vector/build.gradle‎

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@@ -71,6 +71,28 @@ android {
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if (project.hasProperty("coverage")) {
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testCoverageEnabled = project.properties["coverage"] == "true"
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}
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buildConfigField(
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"String",
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"ELEMENT_X_APP_ID",
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"\"io.element.android.x.debug\"",
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)
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buildConfigField(
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"String",
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"ELEMENT_X_FINGERPRINT",
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"\"B0:B0:51:DC:56:5C:81:2F:E1:7F:6F:3E:94:5B:4D:79:04:71:23:AB:0D:A6:12:86:76:9E:B2:94:91:97:13:0E\"",
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)
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}
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release {
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buildConfigField(
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"String",
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"ELEMENT_X_APP_ID",
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"\"io.element.android.x\"",
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)
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buildConfigField(
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"String",
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"ELEMENT_X_FINGERPRINT",
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"\"C6:DB:9B:9C:8C:BD:D6:5D:16:E8:EC:8C:8B:91:C8:31:B9:EF:C9:5C:BF:98:AE:41:F6:A9:D8:35:15:1A:7E:16\"",
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)
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}
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}
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‎vector/src/main/AndroidManifest.xml‎

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@@ -415,6 +415,12 @@
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android:foregroundServiceType="microphone"
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android:permission="android.permission.FOREGROUND_SERVICE_MICROPHONE" />
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<service
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android:name=".features.importer.ImporterService"
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android:exported="true"
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android:process=":remote"
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tools:ignore="ExportedService" />
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<!-- Receivers -->
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<receiver

‎vector/src/main/java/im/vector/app/features/importer/ImporterService.kt‎

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/*
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* Copyright 2026 New Vector Ltd.
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*
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* SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
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* Please see LICENSE files in the repository root for full details.
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*/
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package im.vector.app.features.importer
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import android.app.Service
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import android.content.Intent
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import android.os.Bundle
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import android.os.Handler
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import android.os.IBinder
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import android.os.Looper
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import android.os.Message
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import android.os.Messenger
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import android.os.RemoteException
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import dagger.hilt.android.AndroidEntryPoint
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import im.vector.app.core.di.ActiveSessionHolder
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import kotlinx.coroutines.runBlocking
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import timber.log.Timber
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import javax.inject.Inject
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@AndroidEntryPoint
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class ImporterService : Service() {
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private companion object {
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/**
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* Command to the service to get the data.
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*/
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const val MSG_GET_DATA = 1
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const val KEY_ERROR_STR = "error"
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const val KEY_USER_ID_STR = "userId"
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const val KEY_IS_VERIFIED_BOOLEAN = "isVerified"
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const val KEY_MASTER_PRIVATE_KEY_STR = "masterPrivateKey"
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const val KEY_USER_PRIVATE_KEY_STR = "userPrivateKey"
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const val KEY_SELF_SIGNING_PRIVATE_KEY_STR = "selfSigningPrivateKey"
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const val KEY_KEY_BACKUP_KEY_STR = "keyBackupKey"
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}
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@Inject lateinit var activeSessionHolder: ActiveSessionHolder
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private val signaturePermissionChecker = SignaturePermissionChecker()
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/**
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* Handler of incoming messages from clients.
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*/
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private inner class IncomingHandler : Handler(Looper.getMainLooper()) {
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override fun handleMessage(msg: Message) {
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Timber.w("ImporterService: handling message ${msg.what}")
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val replyTo = msg.replyTo
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if (replyTo == null) {
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Timber.e("ImporterService: no replyTo in the message, cannot answer")
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} else {
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val bundle = Bundle()
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if (signaturePermissionChecker.check(msg.sendingUid, packageManager)) {
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Timber.w("ImporterService: Authorized caller")
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when (msg.what) {
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MSG_GET_DATA -> bundle.putSessionData()
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else -> bundle.putString(KEY_ERROR_STR, "Unknown command ${msg.what}")
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}
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} else {
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Timber.w("ImporterService: Unauthorized caller")
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bundle.putString(KEY_ERROR_STR, "Unauthorized")
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}
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replyTo.sendResponse(msg.what, bundle)
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}
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}
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}
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private fun Bundle.putSessionData() {
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val session = activeSessionHolder.getSafeActiveSession()
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if (session == null) {
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// Keep an empty Bundle to indicate that there is no session
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} else {
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putString(KEY_USER_ID_STR, session.myUserId)
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val crossSigningService = session.cryptoService().crossSigningService()
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val keysBackupService = session.cryptoService().keysBackupService()
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runBlocking {
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// TODO Use method exposed by the SDK (see https://github.com/matrix-org/matrix-rust-sdk/issues/6037)
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putBoolean(KEY_IS_VERIFIED_BOOLEAN, crossSigningService.isCrossSigningVerified())
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crossSigningService.getCrossSigningPrivateKeys()?.let { privateKeys ->
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putString(KEY_MASTER_PRIVATE_KEY_STR, privateKeys.master)
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putString(KEY_SELF_SIGNING_PRIVATE_KEY_STR, privateKeys.selfSigned)
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putString(KEY_USER_PRIVATE_KEY_STR, privateKeys.user)
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}
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val keyBackupKey = keysBackupService.getKeyBackupRecoveryKeyInfo()?.recoveryKey?.toBase64()
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putString(KEY_KEY_BACKUP_KEY_STR, keyBackupKey)
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}
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}
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}
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private fun Messenger.sendResponse(what: Int, bundle: Bundle) {
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Timber.d("ImporterService: send response to client")
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try {
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val message = Message.obtain(null, what).also {
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it.data = bundle
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}
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send(message)
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} catch (e: RemoteException) {
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// The client is dead.
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Timber.e(e, "ImporterService: The client is dead.")
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}
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}
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/**
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* When binding to the service, we return an interface to our messenger
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* for sending messages to the service.
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*/
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override fun onBind(intent: Intent): IBinder? {
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Timber.w("ImporterService: onBind")
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val messenger = Messenger(IncomingHandler())
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return messenger.binder
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}
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override fun onUnbind(intent: Intent?): Boolean {
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Timber.w("ImporterService: onUnbind")
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return super.onUnbind(intent)
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}
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}

‎vector/src/main/java/im/vector/app/features/importer/SignaturePermissionChecker.kt‎

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/*
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* Copyright 2026 New Vector Ltd.
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*
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* SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
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* Please see LICENSE files in the repository root for full details.
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*/
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package im.vector.app.features.importer
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import android.content.pm.PackageInfo
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import android.content.pm.PackageManager
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import android.os.Build
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import im.vector.app.BuildConfig
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import timber.log.Timber
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import java.security.MessageDigest
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class SignaturePermissionChecker {
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/**
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* Check if the calling UID is allowed to access the service.
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* @param sendingUid The UID of the calling process.
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* @param pm The PackageManager to use to get package info.
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* @return True if the calling UID is allowed, false otherwise.
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*/
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fun check(sendingUid: Int, pm: PackageManager): Boolean {
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Timber.w("ImporterService: callingUid: $sendingUid")
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val pkgs = pm.getPackagesForUid(sendingUid) ?: return false
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for (pkg in pkgs) {
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Timber.w("ImporterService: checking package: $pkg")
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if (pkg == BuildConfig.ELEMENT_X_APP_ID && isSignatureAllowed(pkg, pm)) {
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return true
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}
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}
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Timber.e("ImporterService: Unauthorized attempt, denying")
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return false
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}
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private fun isSignatureAllowed(packageName: String, pm: PackageManager): Boolean {
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try {
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val fingerprints = getSignatureFingerprints(pm, packageName)
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if (fingerprints.any { fingerprint ->
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Timber.d("isSignatureAllowed: checking fingerprint $fingerprint")
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fingerprint == BuildConfig.ELEMENT_X_FINGERPRINT
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}
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) {
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return true
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}
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} catch (e: Exception) {
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Timber.w(e, "signature check failed for $packageName")
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}
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Timber.w("isSignatureAllowed: not allowed")
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return false
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}
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private fun getSignatureFingerprints(pm: PackageManager, packageName: String): List<String> {
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val signatures = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.P) {
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val pkgInfo: PackageInfo = pm.getPackageInfo(packageName, PackageManager.GET_SIGNING_CERTIFICATES)
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if (pkgInfo.signingInfo?.hasMultipleSigners() == true) {
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pkgInfo.signingInfo?.apkContentsSigners
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} else {
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pkgInfo.signingInfo?.signingCertificateHistory
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}
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} else {
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@Suppress("DEPRECATION")
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val pkgInfo: PackageInfo = pm.getPackageInfo(packageName, PackageManager.GET_SIGNATURES)
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@Suppress("DEPRECATION")
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pkgInfo.signatures
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}
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if (signatures.isNullOrEmpty()) {
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Timber.w("ImporterService: isSignatureAllowed: no signatures found for package $packageName")
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}
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return signatures.orEmpty().map { sig ->
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sha256Hex(sig.toByteArray())
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}
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}
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private fun sha256Hex(data: ByteArray): String {
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val md = MessageDigest.getInstance("SHA-256")
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val digest = md.digest(data)
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return digest.joinToString(":") { "%02X".format(it) }
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}
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}

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