activity_main.xml
-------------------------
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical"
tools:context="android.anil.com.demoencryptiondecryption.MainActivity">
<EditText
android:id="@+id/editText_value"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10"
android:hint="Enter any value!"
android:inputType="textPersonName" />
<Button
android:id="@+id/button_encryption"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Encrypt" />
<TextView
android:id="@+id/textView_disencry"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="" />
<Button
android:id="@+id/button_discryption"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="Decrypt" />
<TextView
android:id="@+id/textView_disde"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="" />
</LinearLayout>
AESHelper.Java
------------------
package android.anil.com.demoencryptiondecryption.utils;
import android.util.Base64;
import android.util.Log;
import java.io.UnsupportedEncodingException;
import java.security.GeneralSecurityException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
/**
* Created by Anil .
*/
public class AESHelper {
private static final String TAG = "AESCrypt";
//AESCrypt-ObjC uses CBC and PKCS7Padding
private static final String AES_MODE = "AES/CBC/PKCS7Padding";
private static final String CHARSET = "UTF-8";
//AESCrypt-ObjC uses SHA-256 (and so a 256-bit key)
private static final String HASH_ALGORITHM = "SHA-256";
//AESCrypt-ObjC uses blank IV (not the best security, but the aim here is compatibility)
private static final byte[] ivBytes = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
//togglable log option (please turn off in live!)
public static boolean DEBUG_LOG_ENABLED = false;
/**
* Generates SHA256 hash of the password which is used as key
*
* @param password used to generated key
* @return SHA256 of the password
*/
private static SecretKeySpec generateKey(final String password) throws NoSuchAlgorithmException, UnsupportedEncodingException {
final MessageDigest digest = MessageDigest.getInstance(HASH_ALGORITHM);
byte[] bytes = password.getBytes("UTF-8");
digest.update(bytes, 0, bytes.length);
byte[] key = digest.digest();
log("SHA-256 key ", key);
SecretKeySpec secretKeySpec = new SecretKeySpec(key, "AES");
return secretKeySpec;
}
/**
* Encrypt and encode message using 256-bit AES with key generated from password.
*
* @param password used to generated key
* @param message the thing you want to encrypt assumed String UTF-8
* @return Base64 encoded CipherText
* @throws GeneralSecurityException if problems occur during encryption
*/
public static String encrypt(final String password, String message)
throws GeneralSecurityException {
try {
final SecretKeySpec key = generateKey(password);
log("message", message);
byte[] cipherText = encrypt(key, ivBytes, message.getBytes(CHARSET));
//NO_WRAP is important as was getting \n at the end
String encoded = Base64.encodeToString(cipherText, Base64.NO_WRAP);
log("Base64.NO_WRAP", encoded);
return encoded;
} catch (UnsupportedEncodingException e) {
if (DEBUG_LOG_ENABLED)
Log.e(TAG, "UnsupportedEncodingException ", e);
throw new GeneralSecurityException(e);
}
}
/**
* More flexible AES encrypt that doesn't encode
*
* @param key AES key typically 128, 192 or 256 bit
* @param iv Initiation Vector
* @param message in bytes (assumed it's already been decoded)
* @return Encrypted cipher text (not encoded)
* @throws GeneralSecurityException if something goes wrong during encryption
*/
public static byte[] encrypt(final SecretKeySpec key, final byte[] iv, final byte[] message)
throws GeneralSecurityException {
final Cipher cipher = Cipher.getInstance(AES_MODE);
IvParameterSpec ivSpec = new IvParameterSpec(iv);
cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);
byte[] cipherText = cipher.doFinal(message);
log("cipherText", cipherText);
return cipherText;
}
/**
* Decrypt and decode ciphertext using 256-bit AES with key generated from password
*
* @param password used to generated key
* @param base64EncodedCipherText the encrpyted message encoded with base64
* @return message in Plain text (String UTF-8)
* @throws GeneralSecurityException if there's an issue decrypting
*/
public static String decrypt(final String password, String base64EncodedCipherText)
throws GeneralSecurityException {
try {
final SecretKeySpec key = generateKey(password);
log("base64EncodedCipherText", base64EncodedCipherText);
byte[] decodedCipherText = Base64.decode(base64EncodedCipherText, Base64.NO_WRAP);
log("decodedCipherText", decodedCipherText);
byte[] decryptedBytes = decrypt(key, ivBytes, decodedCipherText);
log("decryptedBytes", decryptedBytes);
String message = new String(decryptedBytes, CHARSET);
log("message", message);
return message;
} catch (UnsupportedEncodingException e) {
if (DEBUG_LOG_ENABLED)
Log.e(TAG, "UnsupportedEncodingException ", e);
throw new GeneralSecurityException(e);
}
}
/**
* More flexible AES decrypt that doesn't encode
*
* @param key AES key typically 128, 192 or 256 bit
* @param iv Initiation Vector
* @param decodedCipherText in bytes (assumed it's already been decoded)
* @return Decrypted message cipher text (not encoded)
* @throws GeneralSecurityException if something goes wrong during encryption
*/
public static byte[] decrypt(final SecretKeySpec key, final byte[] iv, final byte[] decodedCipherText)
throws GeneralSecurityException {
final Cipher cipher = Cipher.getInstance(AES_MODE);
IvParameterSpec ivSpec = new IvParameterSpec(iv);
cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
byte[] decryptedBytes = cipher.doFinal(decodedCipherText);
log("decryptedBytes", decryptedBytes);
return decryptedBytes;
}
private static void log(String what, byte[] bytes) {
if (DEBUG_LOG_ENABLED)
Log.d(TAG, what + "[" + bytes.length + "] [" + bytesToHex(bytes) + "]");
}
private static void log(String what, String value) {
if (DEBUG_LOG_ENABLED)
Log.d(TAG, what + "[" + value.length() + "] [" + value + "]");
}
/**
* Converts byte array to hexidecimal useful for logging and fault finding
*
* @param bytes
* @return
*/
private static String bytesToHex(byte[] bytes) {
final char[] hexArray = {'0', '1', '2', '3', '4', '5', '6', '7', '8',
'9', 'A', 'B', 'C', 'D', 'E', 'F'};
char[] hexChars = new char[bytes.length * 2];
int v;
for (int j = 0; j < bytes.length; j++) {
v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars);
}
}
MainActivity.Java
-----------------------------
package android.anil.com.demoencryptiondecryption;
import android.anil.com.demoencryptiondecryption.utils.AESHelper;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
EditText editTextValue;
Button encryptButton, decryptButton;
TextView disEncrypt, disDiscry;
String enValue;
String encryptedString;
String KEY = "ABCDEFGHIJKLMNOPQRSWXYZ0123456789";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
encryptButton = findViewById(R.id.button_encryption);
editTextValue = findViewById(R.id.editText_value);
disEncrypt = findViewById(R.id.textView_disencry);
disDiscry = findViewById(R.id.textView_disde);
decryptButton = findViewById(R.id.button_discryption);
encryptButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
enValue = editTextValue.getText().toString();
if (enValue != null && !enValue.isEmpty()) {
encryptedString = encryption(enValue);
disEncrypt.setText(encryptedString);
} else {
Toast.makeText(MainActivity.this, "Please Enter value", Toast.LENGTH_SHORT).show();
}
}
});
decryptButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String decryptedString = decryption(encryptedString);
disDiscry.setText(decryptedString);
}
});
}
public String encryption(String strNormalText) {
String normalTextEnc = "";
try {
normalTextEnc = AESHelper.encrypt(KEY, strNormalText);
} catch (Exception e) {
e.printStackTrace();
}
return normalTextEnc;
}
public String decryption(String strEncryptedText) {
String strDecryptedText = "";
try {
strDecryptedText = AESHelper.decrypt(KEY, strEncryptedText);
} catch (Exception e) {
e.printStackTrace();
}
return strDecryptedText;
}
}
