Add example for showing how to store encryption key

examples/StoreEncryptionPassword/.gitignore

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+/build

examples/StoreEncryptionPassword/build.gradle

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+apply plugin: 'com.android.application'
+apply plugin: 'realm-android'
+
+android {
+    compileSdkVersion 23
+    buildToolsVersion "23.0.3"
+
+    defaultConfig {
+        applicationId "realm.io.storeencryptionpassword"
+        minSdkVersion 23
+        targetSdkVersion 23
+        versionCode 1
+        versionName "1.0"
+    }
+    buildTypes {
+        release {
+            minifyEnabled false
+            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
+        }
+    }
+}
+
+dependencies {
+    compile fileTree(dir: 'libs', include: ['*.jar'])
+    testCompile 'junit:junit:4.12'
+    //noinspection GradleDependency
+    compile 'com.android.support:appcompat-v7:23.1.1'
+    //noinspection GradleDependency
+    compile 'com.android.support:design:23.1.1'
+}

examples/StoreEncryptionPassword/lint.xml

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+<lint>
+    <issue id="AllowBackup" severity="ignore" />
+    <issue id="IconLauncherShape" severity="ignore" />
+    <issue id="IconMissingDensityFolder" severity="ignore" />
+    <issue id="GoogleAppIndexingWarning" severity="ignore" />
+</lint>

examples/StoreEncryptionPassword/proguard-rules.pro

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+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in /Users/Nabil/Library/Android/sdk/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+
+# Add any project specific keep options here:
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}

examples/StoreEncryptionPassword/src/androidTest/java/realm/io/storeencryptionpassword/ApplicationTest.java

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+package realm.io.storeencryptionpassword;
+
+import android.app.Application;
+import android.test.ApplicationTestCase;
+
+/**
+ * <a href="http://d.android.com/tools/testing/testing_android.html">Testing Fundamentals</a>
+ */
+public class ApplicationTest extends ApplicationTestCase<Application> {
+    public ApplicationTest() {
+        super(Application.class);
+    }
+}

examples/StoreEncryptionPassword/src/main/AndroidManifest.xml

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+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android"
+    package="realm.io.storeencryptionpassword">
+
+    <application
+        android:allowBackup="true"
+        android:icon="@mipmap/ic_launcher"
+        android:label="@string/app_name"
+        android:supportsRtl="true"
+        android:theme="@style/AppTheme">
+        <activity
+            android:name=".MainActivity"
+            android:label="@string/app_name"
+            android:theme="@style/AppTheme.NoActionBar">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
+        <activity android:name=".SecretTodoList"/>
+    </application>
+
+</manifest>

examples/StoreEncryptionPassword/src/main/java/realm/io/storeencryptionpassword/MainActivity.java

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+package realm.io.storeencryptionpassword;
+
+import android.content.Intent;
+import android.os.Bundle;
+import android.support.v7.app.AppCompatActivity;
+import android.support.v7.widget.Toolbar;
+import android.view.View;
+import android.widget.Button;
+import android.widget.Toast;
+
+import java.util.Arrays;
+
+import io.realm.Realm;
+import io.realm.RealmConfiguration;
+
+public class MainActivity extends AppCompatActivity {
+    public static final int REQ_UNLOCK = 1;
+
+    private Button mBtnUnlock;
+    private Button mBtnLock;
+    private View mBtnOpen;
+
+    private final Store store = new Store(this);
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+
+        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
+        setSupportActionBar(toolbar);
+        mBtnUnlock = (Button) findViewById(R.id.btnUnLock);
+        mBtnLock = (Button) findViewById(R.id.btnLock);
+
+        //TODO use this one RealmConfiguration realmConfig = new RealmConfiguration.Builder(this).encryptionKey(realmKey).build();
+        RealmConfiguration realmConfig = new RealmConfiguration.Builder(MainActivity.this).build();
+        Realm.setDefaultConfiguration(realmConfig);
+
+        mBtnUnlock.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                store.unlockKeyStore(REQ_UNLOCK);
+            }
+        });
+
+        mBtnLock.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                mBtnLock.setEnabled(false);
+                Toast.makeText(MainActivity.this, "Locking ...", Toast.LENGTH_SHORT).show();
+                Realm.setDefaultConfiguration(new RealmConfiguration.Builder(MainActivity.this).build());
+                mBtnUnlock.setEnabled(true);
+            }
+        });
+
+        //noinspection ConstantConditions
+        mBtnOpen = findViewById(R.id.btnOpenList);
+        mBtnOpen.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                goToList();
+            }
+        });
+
+        mBtnOpen.setEnabled(store.getEncryptedRealmKey() != null && store.containsEncryptionKey());
+
+        mBtnUnlock.setEnabled(true);
+    }
+
+    @Override
+    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
+        switch (requestCode) {
+            case REQ_UNLOCK:
+                if (store.onUnlockKeyStoreResult(resultCode, data)) {
+                    onKeystoreUnlocked();
+                }
+                break;
+            default:
+                super.onActivityResult(requestCode, resultCode, data);
+                break;
+        }
+    }
+
+    private void onKeystoreUnlocked() {
+        byte[] encryptedRealmKey = store.getEncryptedRealmKey();
+        if (encryptedRealmKey == null || !store.containsEncryptionKey()) {
+            final byte[] realmKey = store.generateKeyForRealm();
+            store.generateKeyInKeystore();
+            encryptedRealmKey = store.encryptAndSaveKeyForRealm(realmKey);
+
+            final RealmConfiguration realmConfig = new RealmConfiguration.Builder(MainActivity.this)
+                    .encryptionKey(realmKey)
+                    .build();
+            Arrays.fill(realmKey, (byte) 0);
+
+            // create encrypted Realm
+            Realm.deleteRealm(realmConfig);
+            Realm.getInstance(realmConfig).close();
+
+            mBtnOpen.setEnabled(true);
+        }
+
+        Toast.makeText(MainActivity.this, "Unlocking ...", Toast.LENGTH_SHORT).show();
+        mBtnUnlock.setEnabled(false);
+
+        final byte[] realmKey = store.decryptKeyForRealm(encryptedRealmKey);
+
+        RealmConfiguration realmConfig = new RealmConfiguration.Builder(MainActivity.this).encryptionKey(realmKey).build();
+        Realm.setDefaultConfiguration(realmConfig);
+
+        mBtnLock.setEnabled(true);
+    }
+
+    private void goToList () {
+        //start Todo list
+        Intent intent = new Intent(MainActivity.this, SecretTodoList.class);
+        startActivity(intent);
+    }
+}

examples/StoreEncryptionPassword/src/main/java/realm/io/storeencryptionpassword/MyAdapter.java

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+package realm.io.storeencryptionpassword;
+
+import android.content.Context;
+import android.view.View;
+import android.view.ViewGroup;
+import android.widget.ListAdapter;
+import android.widget.TextView;
+
+import io.realm.OrderedRealmCollection;
+import io.realm.RealmBaseAdapter;
+import realm.io.storeencryptionpassword.model.TodoItem;
+
+class MyAdapter extends RealmBaseAdapter<TodoItem> implements ListAdapter {
+
+    private static class ViewHolder {
+        TextView name;
+    }
+
+    public MyAdapter(Context context, OrderedRealmCollection<TodoItem> realmResults) {
+        super(context, realmResults, true);
+    }
+
+    @Override
+    public View getView(int position, View convertView, ViewGroup parent) {
+        ViewHolder viewHolder;
+        if (convertView == null) {
+            convertView = inflater.inflate(android.R.layout.simple_list_item_1, parent, false);
+            viewHolder = new ViewHolder();
+            viewHolder.name = (TextView) convertView.findViewById(android.R.id.text1);
+            convertView.setTag(viewHolder);
+        } else {
+            viewHolder = (ViewHolder) convertView.getTag();
+        }
+
+        TodoItem item = adapterData.get(position);
+        viewHolder.name.setText(item.getName());
+        return convertView;
+    }
+
+    public OrderedRealmCollection<TodoItem> getAdapterData() {
+        return adapterData;
+    }
+}

examples/StoreEncryptionPassword/src/main/java/realm/io/storeencryptionpassword/SecretTodoList.java

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+package realm.io.storeencryptionpassword;
+
+import android.app.ListActivity;
+import android.content.Intent;
+import android.os.Bundle;
+import android.os.Message;
+import android.support.design.widget.FloatingActionButton;
+import android.support.design.widget.Snackbar;
+import android.view.View;
+import android.widget.AdapterView;
+import android.widget.ArrayAdapter;
+import android.widget.Toast;
+
+import java.util.Random;
+
+import io.realm.Realm;
+import io.realm.RealmResults;
+import realm.io.storeencryptionpassword.model.TodoItem;
+
+public class SecretTodoList extends ListActivity {
+
+    private Realm realm;
+    private Random random;
+
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        random = new Random();
+
+        realm = getRealm();
+        if (realm == null) {
+            finish();
+            return;
+        }
+        RealmResults<TodoItem> todos = realm.where(TodoItem.class).findAll();
+        setContentView(R.layout.secret_todo);
+        final MyAdapter adapter = new MyAdapter(this, todos);
+        getListView().setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
+            @Override
+            public boolean onItemLongClick(AdapterView<?> adapterView, View view, int i, long l) {
+                TodoItem timeStamp = adapter.getAdapterData().get(i);
+                realm.beginTransaction();
+                timeStamp.deleteFromRealm();
+                realm.commitTransaction();
+                return true;
+            }
+        });
+
+        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
+        fab.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View view) {
+                realm.beginTransaction();
+                TodoItem todoItem = realm.createObject(TodoItem.class);
+                todoItem.setName("Item " + random.nextInt());
+                realm.commitTransaction();
+            }
+        });
+
+        setListAdapter(adapter);
+    }
+
+    private Realm getRealm() {
+        try {
+            return Realm.getDefaultInstance();
+        } catch (IllegalArgumentException e) {
+            Toast.makeText(this, "Please unlock Realm first.", Toast.LENGTH_SHORT).show();
+            return null;
+        }
+    }
+
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        if (realm != null) {
+            realm.close();
+        }
+    }
+}

examples/StoreEncryptionPassword/src/main/java/realm/io/storeencryptionpassword/SharedPrefUtils.java

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+package realm.io.storeencryptionpassword;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.util.Base64;
+
+public final class SharedPrefUtils {
+    private static final String PREF_NAME = "realm_key";
+    private static final String KEY = "iv_and_encrypted_key";
+
+    public static void save(Context context, byte[] ivAndEncryptedKey) {
+        getPreference(context).edit()
+                .putString(KEY, encode(ivAndEncryptedKey))
+                .apply();
+    }
+
+    public static byte[] load(Context context) {
+        final SharedPreferences pref = getPreference(context);
+
+        final String ivAndEncryptedKey = pref.getString(KEY, null);
+        if (ivAndEncryptedKey == null) {
+            return null;
+        }
+
+        return decode(ivAndEncryptedKey);
+    }
+
+    private static String encode(byte[] data) {
+        if (data == null) {
+            return null;
+        }
+        return Base64.encodeToString(data, Base64.NO_WRAP);
+    }
+
+    private static byte[] decode(String encodedData) {
+        if (encodedData == null) {
+            return null;
+        }
+        return Base64.decode(encodedData, Base64.DEFAULT);
+    }
+
+    private static SharedPreferences getPreference(Context context) {
+        return context.getSharedPreferences(PREF_NAME, Context.MODE_PRIVATE);
+    }
+}