import java.io.ByteArrayOutputStream;
 
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
 
/**
 * AES-128
 */
public class EncryptionUtils {
 
	/**
	 * initialisation vector
	 */
	private final static byte[] IV = "thai8bai9voo1haV".getBytes();
 
	/**
	 * algorithm/mode/padding
	 */
	private final static String TRANSFORMATION = "AES/CBC/PKCS5Padding";
 
	/**
	 * 
	 * @param text encrypted text
	 * @param password need have 128-bytes length (16 characters string)
	 * @return
	 * @throws Exception
	 */
    public static String encrypt(String text, String password) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(password.getBytes(), "AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(IV);
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec);
        byte[] encryptedBytes = cipher.doFinal(text.getBytes());
        return toHexString(encryptedBytes);
    }
 
    /**
     * 
     * @param text hex-encoded text do decrypt
     * @param password need have 128-bytes length (16 characters string)
     * @return
     * @throws Exception
     */
    public static String decrypt(String text, String password) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(password.getBytes(), "AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(IV);
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.DECRYPT_MODE, secretKey, ivParameterSpec);
        byte[] decryptedBytes = cipher.doFinal(toBytes(text));
        return new String(decryptedBytes);
    }
 
    private static byte[] toBytes(String hex) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream(hex.length() / 2);
        for (int i = 0; i < hex.length(); i += 2) {
            String output = hex.substring(i, i + 2);
            int decimal = Integer.parseInt(output, 16);
            baos.write(decimal);
        }
        return baos.toByteArray();
    }
 
    private static String toHexString(byte[] encrypted) {
        StringBuilder hex = new StringBuilder();
        for (byte b : encrypted) {
            hex.append(String.format("%02x", b));
        }
        return hex.toString();
    }
 
}