AES Encryption Decryption in Android

This is the easiest way of implementing AES Encryption and Decryption in Android.

import javax.crypto.Cipher;
 import javax.crypto.SecretKey;
 import javax.crypto.spec.SecretKeySpec;

public class AESEncryptionDecryption {

private static final byte[] keyValue =
        new byte[]{'c', 'o', 'd', 'i', 'n', 'g', 'a', 'f', 'f', 'a', 'i', 'r', 's', 'c', 'o', 'm'};


public static String encrypt(String cleartext)
        throws Exception {
    byte[] rawKey = getRawKey();
    byte[] result = encrypt(rawKey, cleartext.getBytes());
    return toHex(result);
}

public static String decrypt(String encrypted)
        throws Exception {

    byte[] enc = toByte(encrypted);
    byte[] result = decrypt(enc);
    return new String(result);
}

private static byte[] getRawKey() throws Exception {
    SecretKey key = new SecretKeySpec(keyValue, "AES");
    byte[] raw = key.getEncoded();
    return raw;
}

private static byte[] encrypt(byte[] raw, byte[] clear) throws Exception {
    SecretKey skeySpec = new SecretKeySpec(raw, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.ENCRYPT_MODE, skeySpec);
    byte[] encrypted = cipher.doFinal(clear);
    return encrypted;
}

private static byte[] decrypt(byte[] encrypted)
        throws Exception {
    SecretKey skeySpec = new SecretKeySpec(keyValue, "AES");
    Cipher cipher = Cipher.getInstance("AES");
    cipher.init(Cipher.DECRYPT_MODE, skeySpec);
    byte[] decrypted = cipher.doFinal(encrypted);
    return decrypted;
}

public static byte[] toByte(String hexString) {
    int len = hexString.length() / 2;
    byte[] result = new byte[len];
    for (int i = 0; i < len; i++)
        result[i] = Integer.valueOf(hexString.substring(2 * i, 2 * i + 2),
                16).byteValue();
    return result;
}

public static String toHex(byte[] buf) {
    if (buf == null)
        return "";
    StringBuffer result = new StringBuffer(2 * buf.length);
    for (int i = 0; i < buf.length; i++) {
        appendHex(result, buf[i]);
    }
    return result.toString();
}

private final static String HEX = "0123456789ABCDEF";

private static void appendHex(StringBuffer sb, byte b) {
    sb.append(HEX.charAt((b >> 4) & 0x0f)).append(HEX.charAt(b & 0x0f));
}

String encrypted = "";
try {
    encrypted = AESEncryptionDecryption.encrypt(plain_text);
    Log.d(Constants.firebase_app, "encrypted:" + encrypted);
} catch (Exception e) {
    e.printStackTrace();
}
*********************************************************************
String decrypted = "";
try {
    decrypted = AESEncryptionDecryption.decrypt(encrypted);
    Log.d(Constants.firebase_app, "decrypted:" + decrypted);
} catch (Exception e) {
    e.printStackTrace();
}

Author:

Hammad Tariq

Android Developer