AES Encryption in Android

MainActivity.java 

package com.example.encryptionexample;

import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;

public class MainActivity extends ActionBarActivity {

    String seedValue = "This Is MySecure";
   
    @Override
    protected void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);
              String normalText = "RAJESH";
           String normalTextEnc;
                  try {
                 AESCrypt a=new AESCrypt(seedValue);
                          TextView txe = new TextView(this);
                          txe.setTextSize(14);
                          txe.setText("Normal Text ::"+normalText +" \n Encrypted Value :: "+ a.encrypt(normalText) +" \n Decrypted value :: "+a.decrypt(a.encrypt(normalText)));
                          setContentView(txe);
                  } catch (Exception e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                  }
       

       
    }
}

AESCrypt.java

package com.example.encryptionexample;

import java.security.MessageDigest;

import java.security.SecureRandom;

import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;

import javax.crypto.KeyGenerator;

import javax.crypto.SecretKey;

import javax.crypto.spec.IvParameterSpec;

import javax.crypto.spec.SecretKeySpec;

import android.util.Base64;

public class AESCrypt {

private final Cipher cipher;

private final SecretKeySpec key;

private AlgorithmParameterSpec spec;

public AESCrypt(String password) throws Exception

{

   // hash password with SHA-256 and crop the output to 128-bit for key

   MessageDigest digest = MessageDigest.getInstance("SHA-256");

   digest.update(password.getBytes("UTF-8"));

   byte[] keyBytes = new byte[32];

   System.arraycopy(digest.digest(), 0, keyBytes, 0, keyBytes.length);

   cipher = Cipher.getInstance("AES/CBC/PKCS7Padding");

   key = new SecretKeySpec(keyBytes, "AES");

   spec = getIV();

}       

public AlgorithmParameterSpec getIV()

{

   byte[] iv = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, };

   IvParameterSpec ivParameterSpec;

   ivParameterSpec = new IvParameterSpec(iv);

   return ivParameterSpec;

}

public String encrypt(String plainText) throws Exception

{

   cipher.init(Cipher.ENCRYPT_MODE, key, spec);

   byte[] encrypted = cipher.doFinal(plainText.getBytes("UTF-8"));

   String encryptedText = new String(Base64.encode(encrypted, Base64.DEFAULT), "UTF-8");

   return encryptedText;

}

public String decrypt(String cryptedText) throws Exception

{

   cipher.init(Cipher.DECRYPT_MODE, key, spec);

   byte[] bytes = Base64.decode(cryptedText, Base64.DEFAULT);

   byte[] decrypted = cipher.doFinal(bytes);

   String decryptedText = new String(decrypted, "UTF-8");

   return decryptedText;

}

}

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.example.encryptionexample.MainActivity">

  <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/hello_world" />

  </RelativeLayout>

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

    package="com.example.encryptionexample"

    android:versionCode="1"

    android:versionName="1.0" >

    <uses-sdk

        android:minSdkVersion="8"

        android:targetSdkVersion="21" />

    <application

        android:allowBackup="true"

        android:icon="@drawable/ic_launcher"

        android:label="@string/app_name"

        android:theme="@style/AppTheme" >

        <activity

            android:name=".MainActivity"

            android:label="@string/app_name" >

            <intent-filter>

                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />

            </intent-filter>

        </activity>

    </application>

</manifest>