Encryption Decryption in JAVA based on Password Based Encryption (PBE) 

   Following program String encryption/decryption done by using AES2 and MD5 algorithm.

public class Encryption {

 

    /**

     * @param args the command line arguments

     */

    public static void main(String[] args) throws Exception {

        Encryption e = new Encryption();

        String pwd = "password";

        String salt = "1234";

        String pwdsalt = pwd.concat(salt);

        String enc = e.Encrypt("This is sample test", pwd, salt);

        System.out.println("Encryption String :"+enc);

        String dec = e.Decrypt(enc, pwd, salt);

        System.out.println("Encryption String :"+dec);

        // TODO code application logic here

    }

    String Decrypt(String text, String pwd, String salt) throws Exception {

        String key = pwd + salt;

        Cipher cipher = Cipher.getInstance("AES");

        byte[] keyBytes = new byte[16];

        byte[] b = key.getBytes("UTF-8");

        int len = b.length;

        if (len > keyBytes.length) {

            len = keyBytes.length;

        }

        System.arraycopy(b, 0, keyBytes, 0, len);

        MessageDigest digest = MessageDigest.getInstance("MD5");

         digest.reset();

         byte[] md5PwdBytes = digest.digest(keyBytes);

        SecretKeySpec keySpec = new SecretKeySpec(md5PwdBytes, "AES");

        //IvParameterSpec ivSpec = new IvParameterSpec(keyBytes);

        cipher.init(Cipher.DECRYPT_MODE, keySpec);

        BASE64Decoder decoder = new BASE64Decoder();

//        NodeList list = doc.getElementsByTagNameNS(

//                    EncryptionConstants.EncryptionSpecNS,

//                    EncryptionConstants._TAG_ENCRYPTEDDATA);

        byte[] results = cipher.doFinal(decoder.decodeBuffer(text));

        return new String(results, "UTF-8");

    }

    String Encrypt(String text, String pwd, String salt)

            throws Exception {

        String key = pwd+salt;

        Cipher cipher = Cipher.getInstance("AES");

        byte[] keyBytes = new byte[16];

        byte[] b = key.getBytes("UTF-8");

        int len = b.length;

        if (len > keyBytes.length) {

            len = keyBytes.length;

        }

        System.arraycopy(b, 0, keyBytes, 0, len);

        MessageDigest digest = MessageDigest.getInstance("MD5");

         digest.reset();

         byte[] md5PwdBytes = digest.digest(keyBytes);

        SecretKeySpec keySpec = new SecretKeySpec(md5PwdBytes, "AES");

        //IvParameterSpec ivSpec = new IvParameterSpec(keyBytes);

        cipher.init(Cipher.ENCRYPT_MODE, keySpec);

        byte[] results = cipher.doFinal(text.getBytes("UTF-8"));

        BASE64Encoder encoder = new BASE64Encoder();

        return encoder.encode(results);

    }

    

    

}