public static String sha1(String s, String keyString)
            throws UnsupportedEncodingException, NoSuchAlgorithmException,
            InvalidKeyException {

        SecretKeySpec key = new SecretKeySpec((keyString).getBytes("UTF-8"),
                "HmacSHA1");
        Mac mac = Mac.getInstance("HmacSHA1");
        mac.init(key);


        byte[] bytes = mac.doFinal(s.getBytes("UTF-8"));

        return new String(Base64.encodeToString(bytes, Base64.DEFAULT));
    }