Google Authenticator In java

TOTPassword.java

public class TOTPassword {
    public static String createGoogleAuthenticatorURI(String user, String host,
        String secret) {
        return new StringBuilder("otpauth://totp/").append(user.toLowerCase().trim())
                                                   .append("@")
                                                   .append(host.toLowerCase().trim())
                                                   .append("?secret=")
                                                   .append(secret.toUpperCase().trim())
                                                   .toString();
    }

    public static String createSecretToken() {
        byte[] buffer = new byte[20];

        new Random().nextBytes(buffer);

        byte[] secretKey = Arrays.copyOf(buffer, 10);

        return Base32.encode(secretKey);
    }
    
   
    public static boolean validate(String secret, long code, long count, int margin)
        throws NoSuchAlgorithmException, InvalidKeyException {
        byte[] decodedKey = Base32.decode(secret);

        for (int i = -margin; i <= margin; ++i) {
            long hash = verificationHash(decodedKey, count + i);

            if (hash == code) {
                return true;
            }
        }

        return false;
    }

    public static boolean validateGoogleAuthenticator(String secret, long code)
        throws NoSuchAlgorithmException, InvalidKeyException {
        return validate(secret, code, System.currentTimeMillis() / 30000, 3);
    }

    public static int verificationHash(String secret, long count)
        throws NoSuchAlgorithmException, InvalidKeyException {
        return verificationHash(Base32.decode(secret), count);
    }

    public static int verificationHash(byte[] decodedSecret, long count)
        throws NoSuchAlgorithmException, InvalidKeyException {
        byte[] data = new byte[8];
        long value = count;

        for (int i = 8; i-- > 0; value >>>= 8) {
            data[i] = (byte) value;
        }

        SecretKeySpec signKey = new SecretKeySpec(decodedSecret, "HmacSHA1");
        Mac mac = Mac.getInstance("HmacSHA1");
        mac.init(signKey);

        byte[] hash = mac.doFinal(data);

        int offset = hash[19] & 0xF;

        long truc = 0;

        for (int i = 0; i < 4; ++i) {
            truc <<= 8;
            truc |= (hash[offset + i] & 0xFF);
        }

        truc &= 0x7FFFFFFF;
        truc %= 1000000;

        return (int) truc;
    }
}