Generate cloud key pair

app/src/main/java/eu/faircode/email/FragmentOptionsBackup.java

@@ -53,6 +53,7 @@ import android.view.inputmethod.EditorInfo;
 import android.widget.Button;
 import android.widget.CheckBox;
 import android.widget.CompoundButton;
+import android.widget.EditText;
 import android.widget.ImageButton;
 import android.widget.TextView;
 import android.widget.Toast;
@@ -81,10 +82,14 @@ import java.io.InputStream;
 import java.io.InputStreamReader;
 import java.io.OutputStream;
 import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
 import java.security.SecureRandom;
+import java.security.spec.InvalidKeySpecException;
 import java.security.spec.KeySpec;
 import java.text.SimpleDateFormat;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
@@ -108,6 +113,9 @@ public class FragmentOptionsBackup extends FragmentBase {
     private Button btnExport;
     private Button btnImport;
     private CardView cardCloud;
+    private EditText etUser;
+    private TextInputLayout tilPassword;
+    private Button btnLogin;
 
     private static final int REQUEST_EXPORT_SELECT = 1;
     private static final int REQUEST_IMPORT_SELECT = 2;
@@ -127,6 +135,9 @@ public class FragmentOptionsBackup extends FragmentBase {
         btnExport = view.findViewById(R.id.btnExport);
         btnImport = view.findViewById(R.id.btnImport);
         cardCloud = view.findViewById(R.id.cardCloud);
+        etUser = view.findViewById(R.id.etUser);
+        tilPassword = view.findViewById(R.id.tilPassword);
+        btnLogin = view.findViewById(R.id.btnLogin);
 
         // Wire controls
 
@@ -153,9 +164,17 @@ public class FragmentOptionsBackup extends FragmentBase {
             }
         });
 
+        btnLogin.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                onLogin();
+            }
+        });
+
         // Initialize
         FragmentDialogTheme.setBackground(getContext(), view, false);
-        cardCloud.setVisibility(BuildConfig.DEBUG ? View.VISIBLE : View.GONE);
+        cardCloud.setVisibility(BuildConfig.DEBUG && Build.VERSION.SDK_INT >= Build.VERSION_CODES.O
+                ? View.VISIBLE : View.GONE);
 
         return view;
     }
@@ -1342,6 +1361,59 @@ public class FragmentOptionsBackup extends FragmentBase {
         return intent;
     }
 
+    private void onLogin() {
+        Bundle args = new Bundle();
+        args.putString("user", etUser.getText().toString());
+        args.putString("password", tilPassword.getEditText().getText().toString());
+
+        new SimpleTask<Void>() {
+            @Override
+            protected void onPreExecute(Bundle args) {
+                btnLogin.setEnabled(false);
+            }
+
+            @Override
+            protected void onPostExecute(Bundle args) {
+                btnLogin.setEnabled(true);
+            }
+
+            @Override
+            protected Void onExecute(Context context, Bundle args) throws Throwable {
+                String user = args.getString("user");
+                String password = args.getString("password");
+
+                Pair<byte[], byte[]> key = getKeyPair(user, password);
+
+                return null;
+            }
+
+            @Override
+            protected void onExecuted(Bundle args, Void data) {
+            }
+
+            @Override
+            protected void onException(Bundle args, Throwable ex) {
+                Log.unexpectedError(getParentFragmentManager(), ex);
+            }
+        }.execute(FragmentOptionsBackup.this, args, "cloud:login");
+    }
+
+    private static Pair<byte[], byte[]> getKeyPair(String user, String password)
+            throws NoSuchAlgorithmException, InvalidKeySpecException {
+        byte[] salt = MessageDigest.getInstance("SHA256").digest(user.getBytes());
+
+        // https://cheatsheetseries.owasp.org/cheatsheets/Password_Storage_Cheat_Sheet.html
+        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
+        KeySpec keySpec = new PBEKeySpec(password.toCharArray(), salt, 310000, 2 * 256);
+        SecretKey secret = keyFactory.generateSecret(keySpec);
+
+        byte[] encoded = secret.getEncoded();
+        int half = encoded.length / 2;
+        return new Pair<>(
+                Arrays.copyOfRange(encoded, 0, half),
+                Arrays.copyOfRange(encoded, half, half + half));
+    }
+
     public static class FragmentDialogExport extends FragmentDialogBase {
         private TextInputLayout tilPassword1;
         private TextInputLayout tilPassword2;

app/src/main/res/drawable/twotone_login_24.xml

@@ -0,0 +1,11 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal"
+    android:autoMirrored="true">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M11,7L9.6,8.4l2.6,2.6H2v2h10.2l-2.6,2.6L11,17l5,-5L11,7zM20,19h-8v2h8c1.1,0 2,-0.9 2,-2V5c0,-1.1 -0.9,-2 -2,-2h-8v2h8V19z"/>
+</vector>

app/src/main/res/drawable/twotone_logout_24.xml

@@ -0,0 +1,11 @@
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal"
+    android:autoMirrored="true">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M5,5h7V3H5C3.9,3 3,3.9 3,5v14c0,1.1 0.9,2 2,2h7v-2H5V5zM21,12l-4,-4v3H9v2h8v3L21,12z"/>
+</vector>

app/src/main/res/layout/fragment_options_backup.xml

@@ -167,6 +167,68 @@
                     app:layout_constraintEnd_toEndOf="parent"
                     app:layout_constraintStart_toStartOf="parent"
                     app:layout_constraintTop_toTopOf="parent" />
+
+                <TextView
+                    android:id="@+id/tvUser"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="12dp"
+                    android:labelFor="@+id/etUser"
+                    android:text="@string/title_user"
+                    android:textAppearance="@style/TextAppearance.AppCompat.Small"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/tvCloud" />
+
+                <eu.faircode.email.EditTextPlain
+                    android:id="@+id/etUser"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    android:autofillHints="username"
+                    android:inputType="text"
+                    android:textAppearance="@style/TextAppearance.AppCompat.Medium"
+                    app:layout_constraintEnd_toEndOf="parent"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/tvUser" />
+
+                <TextView
+                    android:id="@+id/tvPassword"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="12dp"
+                    android:text="@string/title_password"
+                    android:textAppearance="@style/TextAppearance.AppCompat.Small"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/etUser" />
+
+                <com.google.android.material.textfield.TextInputLayout
+                    android:id="@+id/tilPassword"
+                    android:layout_width="0dp"
+                    android:layout_height="wrap_content"
+                    app:endIconMode="password_toggle"
+                    app:layout_constraintEnd_toEndOf="parent"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/tvPassword">
+
+                    <com.google.android.material.textfield.TextInputEditText
+                        android:layout_width="match_parent"
+                        android:layout_height="wrap_content"
+                        android:autofillHints="password"
+                        android:inputType="textPassword"
+                        android:maxLength="20000"
+                        android:textAppearance="@style/TextAppearance.AppCompat.Medium" />
+                </com.google.android.material.textfield.TextInputLayout>
+
+                <Button
+                    android:id="@+id/btnLogin"
+                    style="?android:attr/buttonStyleSmall"
+                    android:layout_width="wrap_content"
+                    android:layout_height="wrap_content"
+                    android:layout_marginTop="12dp"
+                    android:drawableEnd="@drawable/twotone_login_24"
+                    android:drawablePadding="6dp"
+                    android:text="@string/title_advanced_login"
+                    app:layout_constraintStart_toStartOf="parent"
+                    app:layout_constraintTop_toBottomOf="@id/tilPassword" />
             </androidx.constraintlayout.widget.ConstraintLayout>
         </androidx.cardview.widget.CardView>
     </androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -972,6 +972,8 @@
     <string name="title_advanced_cleanup_hint">This will delete all temporary files</string>
     <string name="title_advanced_keywords_hint" translatable="false">Space separated</string>
 
+    <string name="title_advanced_login" translatable="false">Login</string>
+
     <string name="title_advanced_never_favorite">Never favorite</string>
     <string name="title_advanced_edit_name">Edit name</string>