From c37f51bff8d7dacdb6b33725178428d06cf1a997 Mon Sep 17 00:00:00 2001
From: joel <joel@baldaufwd.de>
Date: Sun, 13 Jun 2021 21:38:39 +0200
Subject: [PATCH] Preparations for backup feature

---
 app/src/main/AndroidManifest.xml              |   2 +-
 .../de/joel/zoomhelper/BackupController.java  | 111 +++++++++++++
 .../java/de/joel/zoomhelper/Encrypter.java    | 154 ++++++++++++++++++
 .../java/de/joel/zoomhelper/MainActivity.java |  61 ++++++-
 .../joel/zoomhelper/MeetingsController.java   |   1 +
 app/src/main/res/layout/buttons.xml           |   3 +-
 app/src/main/res/values/strings.xml           |   4 +
 7 files changed, 331 insertions(+), 5 deletions(-)
 create mode 100644 app/src/main/java/de/joel/zoomhelper/BackupController.java
 create mode 100644 app/src/main/java/de/joel/zoomhelper/Encrypter.java

diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 35f2c97..2c0c454 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -11,7 +11,7 @@
 
 
     <application
-        android:allowBackup="true"
+        android:allowBackup="false"
         android:icon="@mipmap/ic_launcher"
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
diff --git a/app/src/main/java/de/joel/zoomhelper/BackupController.java b/app/src/main/java/de/joel/zoomhelper/BackupController.java
new file mode 100644
index 0000000..a5ecf0f
--- /dev/null
+++ b/app/src/main/java/de/joel/zoomhelper/BackupController.java
@@ -0,0 +1,111 @@
+package de.joel.zoomhelper;
+
+import android.annotation.SuppressLint;
+import android.app.Activity;
+import android.content.Context;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.net.Uri;
+import android.os.Build;
+import android.os.Environment;
+
+import androidx.annotation.RequiresApi;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.spec.InvalidKeySpecException;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.NoSuchPaddingException;
+
+public class BackupController {
+
+    @RequiresApi(api = Build.VERSION_CODES.O)
+    public void backup(Activity activity) {
+        Encrypter encrypter = new Encrypter();
+        SharedPreferences mPrefs = activity.getPreferences(Context.MODE_PRIVATE);
+        String value = mPrefs.getString("Meetings", "");
+        File destination = new File(activity.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath(), "backup.tmp");
+
+        try {
+            writeStringToFile(value, destination.getAbsolutePath());
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+        //TODO: Eingabefeld für Passwort
+        try {
+            encrypter.encrypt(destination.getAbsolutePath(), "test");
+        } catch (BadPaddingException | IllegalBlockSizeException | IOException | NoSuchAlgorithmException | InvalidKeySpecException | InvalidAlgorithmParameterException | InvalidKeyException | NoSuchPaddingException e) {
+            e.printStackTrace();
+        }
+        //noinspection ResultOfMethodCallIgnored
+        destination.delete();
+        destination = new File(activity.getExternalFilesDir(Environment.DIRECTORY_DOWNLOADS).getAbsolutePath(), "backup.zoomhelper");
+
+        shareFile(destination, activity);
+
+    }
+
+    public void restore(Activity activity) {
+       new FileChooser(activity).openFile();
+    }
+
+
+    @SuppressLint("ApplySharedPref")
+    public void restore(Activity activity, InputStream inp) {
+        Encrypter encrypter = new Encrypter();
+        SharedPreferences mPrefs = activity.getPreferences(Context.MODE_PRIVATE);
+
+        String decrypted = null;
+
+        //TODO: Passwort einlesen aus Eingabefeld
+        try {
+            decrypted = encrypter.decrypt(inp, "test");
+        } catch (IOException | InvalidAlgorithmParameterException | InvalidKeyException | NoSuchPaddingException | NoSuchAlgorithmException | InvalidKeySpecException | IllegalBlockSizeException | BadPaddingException e) {
+            e.printStackTrace();
+        }
+
+        //TODO: Hinweis, dass Daten mit den Daten aus dem Backup überschrieben werden...
+
+        SharedPreferences.Editor prefsEditor = mPrefs.edit();
+        prefsEditor.putString("Meetings",decrypted);
+        prefsEditor.commit();
+
+        prefsEditor.putString("lastMeeting", "0");
+
+        //TODO: Fehlermeldung bei falschem Passwort
+    }
+
+
+
+    public void writeStringToFile(String str, String fileName)
+            throws IOException {
+        FileOutputStream outputStream = new FileOutputStream(fileName);
+        byte[] strToBytes = str.getBytes();
+        outputStream.write(strToBytes);
+
+        outputStream.close();
+    }
+
+
+    public void shareFile(File file, Activity activity){
+        Intent intentShareFile = new Intent(Intent.ACTION_SEND);
+
+        if(file.exists()) {
+            intentShareFile.setType("application/octet-stream");
+            intentShareFile.putExtra(Intent.EXTRA_STREAM, Uri.parse(file.getAbsolutePath()));
+
+            intentShareFile.putExtra(Intent.EXTRA_SUBJECT,
+                    "Sharing File...");
+            intentShareFile.putExtra(Intent.EXTRA_TEXT, "Sharing File...");
+
+            activity.startActivity(Intent.createChooser(intentShareFile, "Share File"));
+        }
+    }
+}
diff --git a/app/src/main/java/de/joel/zoomhelper/Encrypter.java b/app/src/main/java/de/joel/zoomhelper/Encrypter.java
new file mode 100644
index 0000000..d72ca7f
--- /dev/null
+++ b/app/src/main/java/de/joel/zoomhelper/Encrypter.java
@@ -0,0 +1,154 @@
+package de.joel.zoomhelper;
+
+import android.os.Build;
+import android.os.Environment;
+
+import androidx.annotation.RequiresApi;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.security.InvalidAlgorithmParameterException;
+import java.security.InvalidKeyException;
+import java.security.NoSuchAlgorithmException;
+import java.security.spec.InvalidKeySpecException;
+import java.security.SecureRandom;
+
+import javax.crypto.BadPaddingException;
+import javax.crypto.Cipher;
+import javax.crypto.IllegalBlockSizeException;
+import javax.crypto.NoSuchPaddingException;
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.SecretKeySpec;
+import java.security.spec.KeySpec;
+import javax.crypto.spec.PBEKeySpec;
+import javax.crypto.spec.IvParameterSpec;
+
+public class Encrypter {
+
+    @RequiresApi(api = Build.VERSION_CODES.O)
+    public void encrypt(String inputFile, String password) throws BadPaddingException, IllegalBlockSizeException, IOException, NoSuchAlgorithmException, InvalidKeySpecException, InvalidAlgorithmParameterException, InvalidKeyException, NoSuchPaddingException {
+        SecureRandom srandom = null;
+        try {
+            srandom = SecureRandom.getInstanceStrong();
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+        }
+        byte[] salt = new byte[8];
+        assert srandom != null;
+        srandom.nextBytes(salt);
+        SecretKeyFactory factory =
+                SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
+
+        KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 10000, 128);
+        SecretKey tmp = factory.generateSecret(spec);
+        SecretKeySpec skey = new SecretKeySpec(tmp.getEncoded(), "AES");
+
+        byte[] iv = new byte[128 / 8];
+        srandom.nextBytes(iv);
+        IvParameterSpec ivspec = new IvParameterSpec(iv);
+
+        FileOutputStream out = null;
+        out = new FileOutputStream(inputFile + ".enc");
+        out.write(salt);
+        out.write(iv);
+
+        Cipher ci = null;
+
+        ci = Cipher.getInstance("AES/CBC/PKCS5Padding");
+
+        ci.init(Cipher.ENCRYPT_MODE, skey, ivspec);
+
+        try (FileInputStream in = new FileInputStream(inputFile)) {
+            processFile(ci, in, out);
+        }
+
+    }
+
+    static private void processFile(Cipher ci, InputStream in, OutputStream out)
+            throws javax.crypto.IllegalBlockSizeException,
+            javax.crypto.BadPaddingException,
+            java.io.IOException {
+        byte[] ibuf = new byte[1024];
+        int len;
+        while ((len = in.read(ibuf)) != -1) {
+            byte[] obuf = ci.update(ibuf, 0, len);
+            if (obuf != null) out.write(obuf);
+        }
+        byte[] obuf = ci.doFinal();
+        if (obuf != null) out.write(obuf);
+    }
+
+    @SuppressWarnings("ResultOfMethodCallIgnored")
+    public String decrypt(String inputFile, String password) throws IOException, InvalidAlgorithmParameterException, InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeySpecException, IllegalBlockSizeException, BadPaddingException {
+        FileInputStream in = new FileInputStream(inputFile);
+        byte[] salt = new byte[8], iv = new byte[128 / 8];
+        in.read(salt);
+        in.read(iv);
+
+        SecretKeyFactory factory =
+                SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
+
+        KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 10000, 128);
+        SecretKey tmp = factory.generateSecret(spec);
+        SecretKeySpec skey = new SecretKeySpec(tmp.getEncoded(), "AES");
+
+        Cipher ci = Cipher.getInstance("AES/CBC/PKCS5Padding");
+        ci.init(Cipher.DECRYPT_MODE, skey, new IvParameterSpec(iv));
+
+
+        OutputStream out = new OutputStream() {
+            private final StringBuilder string = new StringBuilder();
+
+            @Override
+            public void write(int b) throws IOException {
+                this.string.append((char) b );
+            }
+
+            //Netbeans IDE automatically overrides this toString()
+            public String toString() {
+                return this.string.toString();
+            }
+        };
+        processFile(ci, in, out);
+        return out.toString();
+    }
+
+    public String decrypt(InputStream in, String password) throws IOException, InvalidAlgorithmParameterException, InvalidKeyException, NoSuchPaddingException, NoSuchAlgorithmException, InvalidKeySpecException, IllegalBlockSizeException, BadPaddingException {
+        byte[] salt = new byte[8], iv = new byte[128 / 8];
+        in.read(salt);
+        in.read(iv);
+
+        SecretKeyFactory factory =
+                SecretKeyFactory.getInstance("PBKDF2WithHmacSHA256");
+
+        KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 10000, 128);
+        SecretKey tmp = factory.generateSecret(spec);
+        SecretKeySpec skey = new SecretKeySpec(tmp.getEncoded(), "AES");
+
+        Cipher ci = Cipher.getInstance("AES/CBC/PKCS5Padding");
+        ci.init(Cipher.DECRYPT_MODE, skey, new IvParameterSpec(iv));
+
+
+        OutputStream out = new OutputStream() {
+            private final StringBuilder string = new StringBuilder();
+
+            @Override
+            public void write(int b) throws IOException {
+                this.string.append((char) b );
+            }
+
+            //Netbeans IDE automatically overrides this toString()
+            public String toString() {
+                return this.string.toString();
+            }
+        };
+        processFile(ci, in, out);
+        return out.toString();
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/de/joel/zoomhelper/MainActivity.java b/app/src/main/java/de/joel/zoomhelper/MainActivity.java
index fa53be2..3be11de 100644
--- a/app/src/main/java/de/joel/zoomhelper/MainActivity.java
+++ b/app/src/main/java/de/joel/zoomhelper/MainActivity.java
@@ -5,7 +5,11 @@ import android.content.ClipData;
 import android.content.ClipboardManager;
 import android.content.Intent;
 import android.net.Uri;
+import android.os.Build;
 import android.os.Bundle;
+import android.view.Menu;
+import android.view.MenuInflater;
+import android.view.MenuItem;
 import android.view.View;
 import android.widget.AutoCompleteTextView;
 import android.widget.EditText;
@@ -14,6 +18,7 @@ import android.widget.LinearLayout;
 import android.widget.ScrollView;
 import android.widget.Toast;
 
+import androidx.annotation.RequiresApi;
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatActivity;
 import androidx.core.content.pm.ShortcutInfoCompat;
@@ -25,6 +30,8 @@ import com.github.javiersantos.appupdater.enums.UpdateFrom;
 import com.google.android.material.snackbar.Snackbar;
 import com.google.android.material.textfield.TextInputLayout;
 
+import java.io.File;
+import java.io.FileNotFoundException;
 import java.util.ArrayList;
 import java.util.Arrays;
 
@@ -140,6 +147,56 @@ public class MainActivity extends AppCompatActivity {
         }
     }
 
+    @Override
+    public boolean onCreateOptionsMenu(Menu menu) {
+        MenuInflater inflater = getMenuInflater();
+        inflater.inflate(R.menu.menu, menu);
+        return true;
+    }
+
+    @RequiresApi(api = Build.VERSION_CODES.O)
+    @Override
+    public boolean onOptionsItemSelected(MenuItem item) {
+        final int item_backup = R.id.menu_backup;
+        final int item_restore = R.id.menu_restore;
+        final int item_settings = R.id.menu_settings;
+        final int item_info = R.id.menu_info;
+        final BackupController backupController = new BackupController();
+
+        switch (item.getItemId()) {
+            case item_backup:
+                backupController.backup(this);
+                break;
+            case item_restore:
+                backupController.restore(this);
+                break;
+            default:
+                break;
+        }
+
+        return true;
+    }
+
+    @Override
+    public void onActivityResult(int requestCode, int resultCode, Intent data) {
+        super.onActivityResult(requestCode, resultCode, data);
+        Uri fileUri = null;
+        String filePath = null;
+
+        if (requestCode == 2) {
+            fileUri = data.getData();
+            filePath = fileUri.getPath();
+        }
+
+        try {
+            new BackupController().restore(this, getContentResolver().openInputStream(fileUri));
+        } catch (FileNotFoundException e) {
+            e.printStackTrace();
+        }
+
+       // new BackupController().restore(this, file.getAbsolutePath());
+    }
+
     private void importFromClipboard() {
         final LinearLayout layoutBegin = findViewById(R.id.layoutBegin);
         final ClipboardManager clipboard = (ClipboardManager) getApplicationContext().getSystemService(CLIPBOARD_SERVICE);
@@ -154,7 +211,7 @@ public class MainActivity extends AppCompatActivity {
 
         if (clipboard.hasPrimaryClip() && clipboard.getPrimaryClipDescription().hasMimeType(MIMETYPE_TEXT_PLAIN)) {
             final String text = clipboard.getPrimaryClip().getItemAt(0).getText().toString();
-            if ( meetingImportController.handleSendText(text, true)) {
+            if (meetingImportController.handleSendText(text, true)) {
                 snackbar.show();
             }
 
@@ -240,7 +297,7 @@ public class MainActivity extends AppCompatActivity {
 
     @SuppressLint("ClickableViewAccessibility")
     public void fillDropdownMeetingName() {
-       final ArrayList<Meeting> meetings = meetingsController.getMeetings();
+        final ArrayList<Meeting> meetings = meetingsController.getMeetings();
 
         String[] meetingNames = new String[meetings.size()];
         for (int i = 0; i < meetings.size(); i++) {
diff --git a/app/src/main/java/de/joel/zoomhelper/MeetingsController.java b/app/src/main/java/de/joel/zoomhelper/MeetingsController.java
index 2007592..569ea4e 100644
--- a/app/src/main/java/de/joel/zoomhelper/MeetingsController.java
+++ b/app/src/main/java/de/joel/zoomhelper/MeetingsController.java
@@ -119,6 +119,7 @@ public class MeetingsController {
         return meetingList;
     }
 
+    //TODO: Nach Remove bleibt Meeting noch stehen
     public void removeMeeting(int meeting) {
         MainActivity act = (MainActivity)context;
         ArrayList<Meeting> meetings = getMeetings();
diff --git a/app/src/main/res/layout/buttons.xml b/app/src/main/res/layout/buttons.xml
index 3e3ab72..84052fc 100644
--- a/app/src/main/res/layout/buttons.xml
+++ b/app/src/main/res/layout/buttons.xml
@@ -11,8 +11,7 @@
         android:layout_marginTop="22dp"
         android:onClick="btnSave_onClick"
         android:text="@string/Save"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/imageTrash" />
+        app:layout_constraintStart_toStartOf="parent" />
 
     <Button
         android:id="@+id/btnJoin"
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index dbe7cea..5dcd10a 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -41,5 +41,9 @@
     <string name="cancel">abbrechen</string>
     <string name="meetingSaved">Meeting gespeichert</string>
     <string name="meetingWithoutID">Meeting kann nicht ohne ID gespeichert werden!</string>
+    <string name="backup">Daten sichern</string>
+    <string name="restore">Daten wiederherstellen</string>
+    <string name="settings">Einstellungen</string>
+    <string name="info">Info</string>
 
 </resources>
\ No newline at end of file