Add client attestion to the mail authentication

app/src/main/java/io/timelimit/android/sync/network/api/Api.kt

@@ -1,5 +1,5 @@
 /*
- * TimeLimit Copyright <C> 2019 - 2023 Jonas Lochmann
+ * TimeLimit Copyright <C> 2019 - 2024 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -61,3 +61,4 @@ interface ServerApi {
 
 class MailServerBlacklistedException: RuntimeException()
 class MailAddressNotWhitelistedException: RuntimeException()
+class MailLoginBlockedForIntegrityReasonsException: RuntimeException()

app/src/main/java/io/timelimit/android/sync/network/api/HttpServerApi.kt

@@ -1,5 +1,5 @@
 /*
- * TimeLimit Copyright <C> 2019 - 2023 Jonas Lochmann
+ * TimeLimit Copyright <C> 2019 - 2024 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -15,9 +15,14 @@
  */
 package io.timelimit.android.sync.network.api
 
+import android.os.Build.VERSION
+import android.os.Build.VERSION_CODES
+import android.security.keystore.KeyGenParameterSpec
+import android.security.keystore.KeyProperties
 import android.util.JsonReader
 import android.util.JsonWriter
 import android.util.Log
+import de.wivewa.android.network.X509ClientKeyManager
 import io.timelimit.android.BuildConfig
 import io.timelimit.android.async.Threads
 import io.timelimit.android.coroutines.executeAndWait
@@ -25,6 +30,7 @@ import io.timelimit.android.coroutines.waitForResponse
 import io.timelimit.android.sync.network.*
 import io.timelimit.android.util.okio.LengthSink
 import okhttp3.MediaType.Companion.toMediaTypeOrNull
+import okhttp3.OkHttpClient
 import okhttp3.Request
 import okhttp3.RequestBody
 import okhttp3.Response
@@ -34,6 +40,14 @@ import okio.GzipSink
 import okio.Sink
 import okio.buffer
 import java.io.OutputStreamWriter
+import java.security.KeyPairGenerator
+import java.security.KeyStore
+import java.security.KeyStore.PrivateKeyEntry
+import java.security.cert.X509Certificate
+import java.security.spec.ECGenParameterSpec
+import java.util.Date
+import java.util.UUID
+import javax.net.ssl.SSLContext
 
 class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
     companion object {
@@ -125,9 +139,10 @@ class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
         }
     }
 
-    override suspend fun sendMailLoginCode(mail: String, locale: String, deviceAuthToken: String?): String {
+    override suspend fun sendMailLoginCode(mail: String, locale: String, deviceAuthToken: String?): String = withDeviceVerification { client ->
         postJsonRequest(
-            "auth/send-mail-login-code-v2"
+            "auth/send-mail-login-code-v2",
+            client = client
         ) { writer ->
             writer.beginObject()
             writer.name(MAIL).value(mail)
@@ -145,7 +160,7 @@ class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
                         Log.d(LOG_TAG, "sendMailLoginCode() try again without deviceAuthToken")
                     }
 
-                    return sendMailLoginCode(mail, locale, null)
+                    return@use sendMailLoginCode(mail, locale, null)
                 } else {
                     throw ex
                 }
@@ -153,7 +168,7 @@ class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
 
             val body = it.body!!
 
-            return Threads.network.executeAndWait {
+            return@use Threads.network.executeAndWait {
                 var response: String? = null
 
                 JsonReader(body.charStream()).use { reader ->
@@ -172,6 +187,11 @@ class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
                                     throw MailAddressNotWhitelistedException()
                                 }
                             }
+                            "blockedForIntegrityReasons" -> {
+                                if (reader.nextBoolean()) {
+                                    throw MailLoginBlockedForIntegrityReasonsException()
+                                }
+                            }
                             else -> reader.skipValue()
                         }
                     }
@@ -627,10 +647,11 @@ class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
 
     private suspend fun postJsonRequest(
         path: String,
+        client: OkHttpClient = httpClient,
         requestBody: (writer: JsonWriter) -> Unit
     ): Response {
         if (!sendContentLength) {
-            val response = postJsonRequest(path, requestBody, transmitContentLength = false)
+            val response = postJsonRequest(path, requestBody, transmitContentLength = false, client = client)
 
             if (response.code != 411) return response
 
@@ -639,17 +660,18 @@ class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
             sendContentLength = true
         }
 
-        return postJsonRequest(path, requestBody, transmitContentLength = true)
+        return postJsonRequest(path, requestBody, transmitContentLength = true, client = client)
     }
 
     private suspend fun postJsonRequest(
         path: String,
         requestBody: (writer: JsonWriter) -> Unit,
-        transmitContentLength: Boolean
+        transmitContentLength: Boolean,
+        client: OkHttpClient = httpClient
     ): Response {
         val body = createJsonRequestBody(requestBody, transmitContentLength)
 
-        return httpClient.newCall(
+        return client.newCall(
             Request.Builder()
                 .url("$endpointWithoutSlashAtEnd/$path")
                 .post(body)
@@ -657,4 +679,53 @@ class HttpServerApi(private val endpointWithoutSlashAtEnd: String): ServerApi {
                 .build()
         ).waitForResponse()
     }
+
+    private suspend fun <T> withDeviceVerification(block: suspend (client: OkHttpClient) -> T): T {
+        if (VERSION.SDK_INT >= VERSION_CODES.N) {
+            val keyStoreName = "AndroidKeyStore"
+            val keyStore = KeyStore.getInstance(keyStoreName).also { it.load(null) }
+            val keyId = "temp-" + UUID.randomUUID().toString()
+            val now = getTimeInMillis()
+
+            KeyPairGenerator.getInstance(KeyProperties.KEY_ALGORITHM_EC, keyStoreName)
+                .also {
+                    it.initialize(
+                        KeyGenParameterSpec.Builder(
+                            keyId,
+                            KeyProperties.PURPOSE_SIGN
+                        )
+                            .setAlgorithmParameterSpec(
+                                ECGenParameterSpec("prime256v1")
+                            )
+                            .setDigests(
+                                KeyProperties.DIGEST_NONE,
+                                KeyProperties.DIGEST_SHA256,
+                                KeyProperties.DIGEST_SHA384,
+                                KeyProperties.DIGEST_SHA512
+                            )
+                            .setCertificateNotBefore(Date(now - 1000 * 60))
+                            .setCertificateNotAfter(Date(now + 1000 * 60))
+                            .setAttestationChallenge(byteArrayOf())
+                            .build()
+                    )
+                }.genKeyPair()
+
+            try {
+                val key = keyStore.getEntry(keyId, null) as PrivateKeyEntry
+                val keyManager = X509ClientKeyManager(key.privateKey, key.certificateChain.map { it as X509Certificate })
+
+                val socketFactory = SSLContext.getInstance("TLS").also {
+                    it.init(arrayOf(keyManager), null, null)
+                }.socketFactory
+
+                return block(
+                    httpClient.newBuilder()
+                        .sslSocketFactory(socketFactory, httpClient.x509TrustManager!!)
+                        .build()
+                )
+            } finally {
+                keyStore.deleteEntry(keyId)
+            }
+        } else return block(httpClient)
+    }
 }

app/src/main/java/io/timelimit/android/sync/network/api/X509ClientKeyManager.kt

@@ -0,0 +1,63 @@
+/*
+ * TimeLimit Copyright <C> 2019 - 2024 Jonas Lochmann
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation version 3 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+package de.wivewa.android.network
+
+import java.net.Socket
+import java.security.Principal
+import java.security.PrivateKey
+import java.security.cert.X509Certificate
+import javax.net.ssl.X509KeyManager
+
+class X509ClientKeyManager(
+    private val privateKey: PrivateKey,
+    private val certificateChain: List<X509Certificate>
+): X509KeyManager {
+    companion object {
+        private const val ALIAS_NAME = "key"
+    }
+
+    override fun chooseClientAlias(
+        keyType: Array<out String>,
+        principal: Array<out Principal>?,
+        socket: Socket?
+    ): String = ALIAS_NAME
+
+    override fun chooseServerAlias(
+        keyType: String,
+        principal: Array<out Principal>?,
+        socket: Socket?
+    ): String? = null
+
+    override fun getCertificateChain(alias: String): Array<X509Certificate>? = when (alias) {
+        ALIAS_NAME -> certificateChain.toTypedArray()
+        else -> null
+    }
+
+    override fun getClientAliases(
+        keyType: String,
+        issuers: Array<out Principal>?
+    ): Array<String> = arrayOf(ALIAS_NAME)
+
+    override fun getPrivateKey(alias: String): PrivateKey? = when (alias) {
+        ALIAS_NAME -> privateKey
+        else -> null
+    }
+
+    override fun getServerAliases(
+        keyType: String,
+        issuers: Array<out Principal>?
+    ): Array<String> = emptyArray()
+}

app/src/main/java/io/timelimit/android/ui/authentication/AuthenticateByMailScreen.kt

@@ -1,5 +1,5 @@
 /*
- * TimeLimit Copyright <C> 2019 - 2023 Jonas Lochmann
+ * TimeLimit Copyright <C> 2019 - 2024 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -154,6 +154,11 @@ fun AuthenticateByMailError(error: MailAuthentication.ErrorDialog, close: () ->
             stringResource(R.string.authenticate_not_whitelisted_address_text),
             close
         )
+        MailAuthentication.ErrorDialog.BlockedForIntegrityReasons -> SimpleErrorDialog(
+            stringResource(R.string.authenticate_error_integrity_title),
+            stringResource(R.string.authenticate_error_integrity_text),
+            close
+        )
         is MailAuthentication.ErrorDialog.ExceptionDetails -> DiagnoseExceptionDialog(error.message, close)
     }
 }

app/src/main/java/io/timelimit/android/ui/model/mailauthentication/MailAuthentication.kt

@@ -1,5 +1,5 @@
 /*
- * TimeLimit Copyright <C> 2019 - 2023 Jonas Lochmann
+ * TimeLimit Copyright <C> 2019 - 2024 Jonas Lochmann
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -129,6 +129,7 @@ object MailAuthentication {
         object RateLimit: ErrorDialog()
         object BlockedMailServer: ErrorDialog()
         object MailAddressNotAllowed: ErrorDialog()
+        object BlockedForIntegrityReasons: ErrorDialog()
         data class ExceptionDetails(val message: String): ErrorDialog()
     }
 
@@ -188,6 +189,8 @@ object MailAuthentication {
                 updateState { it.withError(error = ErrorDialog.BlockedMailServer) }
             } catch (ex: MailAddressNotWhitelistedException) {
                 updateState { it.withError(error = ErrorDialog.MailAddressNotAllowed) }
+            } catch (ex: MailLoginBlockedForIntegrityReasonsException) {
+                updateState { it.withError(error = ErrorDialog.BlockedForIntegrityReasons) }
             } catch (ex: Exception) {
                 showGenericExceptionMessage(ex)
             }

app/src/main/res/values-de/strings.xml

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <!--
-  TimeLimit Copyright <C> 2019 - 2023 Jonas Lochmann
+  TimeLimit Copyright <C> 2019 - 2024 Jonas Lochmann
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation version 3 of the License.
@@ -164,6 +164,8 @@
         serverseitig eine Whitelist mit E-Mail-Adressen festgelegt und die angegebene E-Mail-Adresse war nicht
         in dieser Whitelist
     </string>
+    <string name="authenticate_error_integrity_title">Anmeldung blockiert</string>
+    <string name="authenticate_error_integrity_text">Wegen einem Problem mit Ihrem Gerät oder Ihrer TimeLimit-Installation ist keine Anmeldung möglich.</string>
     <string name="authenticate_too_many_requests_text">Es gab viele Anmeldeversuche, daher gibt es eine vorübergehende Anmeldesperre.
         Diese Sperre wird automatisch deaktiviert.
     </string>

app/src/main/res/values/strings.xml

@@ -206,6 +206,8 @@
         side whitelist of mail addresses and the specified mail address is not
         in this whitelist
     </string>
+    <string name="authenticate_error_integrity_title">Login blocked</string>
+    <string name="authenticate_error_integrity_text">Due to an issue with your TimeLimit installation or your device, you can not sign in.</string>
     <string name="authenticate_too_many_requests_text">There were much login attempts.
         Due to that, signing in is temporarily blocked.
         This blocking is disabled automatically.