Merge pull request #858 from opensrp/encrypt-file-example

Encrypt file example

README.md

@@ -128,6 +128,9 @@ _**void generateKey(String keyAlias)**_ For key generation using a Key Alias par
 
 - NB: \* This class depends on `AndroidLegacyCryptography` class and the `AndroidMCryptography` class which both implement the above in different ways depending on the SDK version.
   `AndroidLegacyCryptography` has method implementation that are used when the SDK version is less than API level 23
+
+The sample app has examples of how these methods have been implemented. The code for it can be found in
+the [MainActivity](https://github.com/opensrp/opensrp-client-core/blob/master/sample/src/main/java/org/smartregister/sample/MainActivity.java) class.
 
 ## 2. Data management
 

opensrp-core/src/main/java/org/smartregister/cryptography/AndroidMCryptography.java

@@ -73,8 +73,7 @@ public byte[] decrypt(byte[] encrypted, String keyAlias) {
 
             Cipher c = Cipher.getInstance(AES_MODE);
             c.init(Cipher.DECRYPT_MODE, getKey(keyAlias), new GCMParameterSpec(128, INITIALIZATION_VECTOR));
-            byte[] decodedBytes = c.doFinal(encrypted);
-            return decodedBytes;
+            return c.doFinal(encrypted);
         } catch (Exception e) {
 
             Timber.e(e);

sample/src/main/java/org/smartregister/sample/MainActivity.java

@@ -1,6 +1,7 @@
 package org.smartregister.sample;
 
 import android.app.Activity;
+import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
 import android.view.Menu;
@@ -9,9 +10,11 @@
 import android.widget.AdapterView;
 import android.widget.ArrayAdapter;
 import android.widget.Button;
+import android.widget.CompoundButton;
 import android.widget.DatePicker;
 import android.widget.Spinner;
 import android.widget.TextView;
+import android.widget.ToggleButton;
 
 import androidx.appcompat.widget.Toolbar;
 
@@ -20,23 +23,31 @@
 
 import org.joda.time.DateTime;
 import org.joda.time.LocalDate;
+import org.smartregister.cryptography.CryptographicHelper;
 import org.smartregister.cursoradapter.SmartRegisterQueryBuilder;
 import org.smartregister.sample.fragment.ReportFragment;
 import org.smartregister.util.AppHealthUtils;
 import org.smartregister.util.DateUtil;
 import org.smartregister.util.LangUtils;
 import org.smartregister.view.activity.MultiLanguageActivity;
 
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Locale;
 
+import timber.log.Timber;
+
 public class MainActivity extends MultiLanguageActivity {
 
     DatePicker picker;
     Button btnGet;
     TextView tvw;
-
+    CryptographicHelper cryptographicHelper = null;
+    TextView encDecTextView;
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
@@ -49,6 +60,7 @@ protected void onCreate(Bundle savedInstanceState) {
         Activity activity = this;
         tvw = (TextView) findViewById(R.id.textView1);
         picker = (DatePicker) findViewById(R.id.datePicker1);
+        encDecTextView = (TextView) findViewById(R.id.encrypt_decrypt_tv);
 
         picker.setMinDate(new LocalDate().minusYears(2).toDate().getTime());
 
@@ -140,6 +152,80 @@ public void onNothingSelected(AdapterView<?> parent) {
         ((TextView) findViewById(R.id.time)).setText(DateUtil.getDuration(new DateTime().minusYears(4).minusMonths(3).minusWeeks(2).minusDays(1)));
 
         new AppHealthUtils(findViewById(R.id.show_sync_stats));
+
+        // File encryption example section
+        ToggleButton toggle = (ToggleButton) findViewById(R.id.encrypt_decrypt_toggle);
+        cryptographicHelper = CryptographicHelper.getInstance(this);
+        String filename = "test.txt";
+        String contents = getString(R.string.encrypt_decrypt_string);
+        // Create a file with the contents above
+        try (FileOutputStream fos = MainActivity.this.openFileOutput(filename, Context.MODE_PRIVATE)) {
+            fos.write(contents.getBytes());
+            fos.flush();
+        } catch (FileNotFoundException e) {
+            e.printStackTrace();
+        } catch (IOException e) {
+            e.printStackTrace();
+        }
+
+
+        toggle.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                String keyAlias = "sample";
+                // Get or create a key with the Alias name sample or create one if id does not exist
+                if(cryptographicHelper.getKey(keyAlias)==null)
+                {
+                    cryptographicHelper.generateKey(keyAlias);
+                    Timber.i("key with alias %s generated",keyAlias);
+                }
+
+                if (isChecked) {
+
+                    try {
+                        // read the text.txt while it is in plain text and write to file
+                        FileInputStream inputStream = openFileInput(filename);
+                        byte[] inputBytes = new byte[inputStream.available()];
+                        inputStream.read(inputBytes);
+                        byte[] encryptedContents = CryptographicHelper.encrypt(inputBytes, keyAlias);
+                        FileOutputStream fileOutputStream = openFileOutput(filename, Context.MODE_PRIVATE);
+                        Timber.i("encrypted stuff to write %S ",new String(encryptedContents));
+                        encDecTextView.setText(new String(encryptedContents));
+                        fileOutputStream.write((encryptedContents));
+                        fileOutputStream.flush();
+
+
+                    } catch (IOException e) {
+                        e.printStackTrace();
+                    }
+
+                } else {
+                        try {
+                            //
+                            FileInputStream inputStream = openFileInput(filename);
+                            byte[] inputBytes = new byte[inputStream.available()];
+                            inputStream.read(inputBytes);
+                            Timber.i("before decryption %s", new String(inputBytes));
+
+                            byte[] decryptedStuff =  CryptographicHelper.decrypt(inputBytes, keyAlias);
+                            encDecTextView.setText(new String(decryptedStuff));
+                            Timber.i("decrypted content %s", new String(decryptedStuff));
+
+                            FileOutputStream fileOutputStream = openFileOutput(filename, Context.MODE_PRIVATE);
+                            fileOutputStream.write((decryptedStuff));
+                            fileOutputStream.flush();
+
+
+                        } catch (IOException e) {
+                            e.printStackTrace();
+                            // Error occurred when opening raw file for reading.
+                        }
+
+
+                }
+            }
+        });
+
+
     }
 
     @Override
@@ -166,4 +252,10 @@ public boolean onOptionsItemSelected(MenuItem item) {
 
         return super.onOptionsItemSelected(item);
     }
+
+    @Override
+    protected void onDestroy() {
+        super.onDestroy();
+        cryptographicHelper = null;
+    }
 }

sample/src/main/res/layout-v17/content_main.xml

@@ -91,5 +91,29 @@
             android:text="@string/sync_stats_label" />
 
     </LinearLayout>
+    <LinearLayout
+        android:id="@+id/cryptography_layout"
+        android:layout_below="@+id/sync_stats_layout"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:layout_marginTop="10dp"
+        android:layout_centerHorizontal="true">
+        <TextView
+            android:id="@+id/encrypt_decrypt_tv"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/encrypt_decrypt_string"
+            />
+
+
+        <ToggleButton
+            android:id="@+id/encrypt_decrypt_toggle"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:textOff="@string/encrypt"
+            android:textOn="@string/decrypt"
+            android:layout_marginLeft="100dp"/>
+    </LinearLayout>
 
 </RelativeLayout>

sample/src/main/res/layout/content_main.xml

@@ -91,5 +91,29 @@
             android:text="@string/sync_stats_label" />
 
     </LinearLayout>
+    <LinearLayout
+        android:id="@+id/cryptography_layout"
+        android:layout_below="@+id/sync_stats_layout"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:orientation="vertical"
+        android:layout_marginTop="10dp"
+        android:layout_centerHorizontal="true">
+        <TextView
+            android:id="@+id/encrypt_decrypt_tv"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="@string/encrypt_decrypt_string"
+         />
+
+
+        <ToggleButton
+            android:id="@+id/encrypt_decrypt_toggle"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:textOff="@string/encrypt"
+            android:textOn="@string/decrypt"
+            android:layout_marginLeft="100dp"/>
+    </LinearLayout>
 
 </RelativeLayout>

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

@@ -7,4 +7,7 @@
     <string name="action_report_sample">Sample Reports</string>
     <string name="action_sync_stats">Sync Statistics</string>
     <string name="sync_stats_label">Show Sync Stats (Long Press for Dialog)</string>
+    <string name="encrypt_decrypt_string">Please encrypt or decrypt me by hitting clicking on the switch below</string>
+    <string name="encrypt">Encrypt</string>
+    <string name="decrypt">Decrypt</string>
 </resources>