private static byte[] hmac(String algorithm, byte[] data, byte[] key) {
        try {
            Mac mac = Mac.getInstance(algorithm);
            mac.init(new SecretKeySpec(key, algorithm));
            return mac.doFinal(data);
        } catch (InvalidKeyException | NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
    }
Parse ISO 8601 timestamp into seconds since 1970.
src/main/java/org/gaul/s3proxy/S3ProxyHandler.java