Fix backup authdata serialization

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/model/rest/DefaultKeysAlgorithmAndData.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.matrix.android.sdk.internal.crypto.keysbackup.model.rest
+
+import com.squareup.moshi.Json
+import com.squareup.moshi.JsonClass
+import org.matrix.android.sdk.api.util.JsonDict
+
+@JsonClass(generateAdapter = true)
+internal data class DefaultKeysAlgorithmAndData(
+        /**
+         * The algorithm used for storing backups. Currently, only "m.megolm_backup.v1.curve25519-aes-sha2" is defined.
+         */
+        @Json(name = "algorithm")
+        override val algorithm: String,
+
+        /**
+         * algorithm-dependent data, for "m.megolm_backup.v1.curve25519-aes-sha2".
+         * see [org.matrix.android.sdk.internal.crypto.keysbackup.MegolmBackupAuthData]
+         */
+        @Json(name = "auth_data")
+        override val authData: JsonDict
+) : KeysAlgorithmAndData

matrix-sdk-android/src/rustCrypto/java/org/matrix/android/sdk/internal/crypto/OlmMachine.kt

@@ -52,6 +52,9 @@ import org.matrix.android.sdk.api.util.JsonDict
 import org.matrix.android.sdk.api.util.Optional
 import org.matrix.android.sdk.api.util.toOptional
 import org.matrix.android.sdk.internal.coroutines.builder.safeInvokeOnClose
+import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.CreateKeysBackupVersionBody
+import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.DefaultKeysAlgorithmAndData
+import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.KeysAlgorithmAndData
 import org.matrix.android.sdk.internal.crypto.network.RequestSender
 import org.matrix.android.sdk.internal.crypto.verification.SasVerification
 import org.matrix.android.sdk.internal.crypto.verification.VerificationRequest
@@ -860,14 +863,19 @@ internal class OlmMachine @Inject constructor(
     }
 
     @Throws(CryptoStoreException::class)
-    suspend fun checkAuthDataSignature(authData: MegolmBackupAuthData): Boolean {
+    suspend fun checkAuthDataSignature(authData: KeysAlgorithmAndData): Boolean {
         return withContext(coroutineDispatchers.computation) {
             val adapter = moshi
                     .newBuilder()
-                    .add(CheckNumberType.JSON_ADAPTER_FACTORY)
                     .build()
-                    .adapter(MegolmBackupAuthData::class.java)
+                    .adapter(DefaultKeysAlgorithmAndData::class.java)
-            val serializedAuthData = adapter.toJson(authData)
+            val serializedAuthData = adapter.toJson(
+                    DefaultKeysAlgorithmAndData(
+                            algorithm = authData.algorithm,
+                            authData = authData.authData
+                    )
+            )
+
             inner.verifyBackup(serializedAuthData).trusted
         }
     }

matrix-sdk-android/src/rustCrypto/java/org/matrix/android/sdk/internal/crypto/keysbackup/RustKeyBackupService.kt

@@ -54,6 +54,7 @@ import org.matrix.android.sdk.internal.crypto.OlmMachine
 import org.matrix.android.sdk.internal.crypto.keysbackup.model.SignalableMegolmBackupAuthData
 import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.CreateKeysBackupVersionBody
 import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.KeyBackupData
+import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.KeysAlgorithmAndData
 import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.KeysBackupData
 import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.UpdateKeysBackupVersionBody
 import org.matrix.android.sdk.internal.crypto.network.RequestSender
@@ -259,19 +260,20 @@ internal class RustKeyBackupService @Inject constructor(
 //        TODO()
 //    }
 
-    private suspend fun checkBackupTrust(authData: MegolmBackupAuthData?): KeysBackupVersionTrust {
+    private suspend fun checkBackupTrust(algAndData: KeysAlgorithmAndData?): KeysBackupVersionTrust {
-        return if (authData == null || authData.publicKey.isEmpty() || authData.signatures.isNullOrEmpty()) {
+        if (algAndData == null) return KeysBackupVersionTrust(usable = false)
-            Timber.v("getKeysBackupTrust: Key backup is absent or missing required data")
+        try {
-            KeysBackupVersionTrust(usable = false)
+            val isTrusted = olmMachine.checkAuthDataSignature(algAndData)
-        } else {
+            return KeysBackupVersionTrust(isTrusted)
-            KeysBackupVersionTrust(olmMachine.checkAuthDataSignature(authData))
+        } catch (failure: Throwable) {
+            Timber.w(failure, "Failed to trust backup")
+            return KeysBackupVersionTrust(usable = false)
         }
     }
 
     override suspend fun getKeysBackupTrust(keysBackupVersion: KeysVersionResult): KeysBackupVersionTrust {
-        val authData = keysBackupVersion.getAuthDataAsMegolmBackupAuthData()
         return withContext(coroutineDispatchers.crypto) {
-            checkBackupTrust(authData)
+            checkBackupTrust(keysBackupVersion)
         }
     }