Encrypt databases used by the Rust SDK.

The passphrase is stored in the SessionData, so that a Session created by Element Android can be restored.
Existing sessions will have a null passphrase and will continue to work.
New session will use a passphrase, only on Nightly and Debug build for now.

samples/minimal/src/main/kotlin/io/element/android/samples/minimal/MainActivity.kt

@@ -55,7 +55,9 @@ class MainActivity : ComponentActivity() {
                 sessionStore = sessionStore,
                 userAgentProvider = userAgentProvider,
                 clock = DefaultSystemClock(),
-            )
+            ),
+            passphraseGenerator = NullPassphraseGenerator(),
+            buildMeta = Singleton.buildMeta,
         )
     }
 

samples/minimal/src/main/kotlin/io/element/android/samples/minimal/NullPassphraseGenerator.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2024 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 io.element.android.samples.minimal
+
+import io.element.android.libraries.matrix.impl.keys.PassphraseGenerator
+
+class NullPassphraseGenerator : PassphraseGenerator {
+    override fun generatePassphrase(): String? = null
+}

samples/minimal/src/main/kotlin/io/element/android/samples/minimal/Singleton.kt

@@ -29,7 +29,7 @@ import kotlinx.coroutines.MainScope
 import kotlinx.coroutines.plus
 
 object Singleton {
-    private val buildMeta = BuildMeta(
+    val buildMeta = BuildMeta(
         isDebuggable = true,
         buildType = BuildType.DEBUG,
         applicationName = "EAX-Minimal",