public static string HashString(string strToHash, string strMerchantKey)
        {
            string Hash = null;

            SubscriptionAPI SubscriptionAPIObj = new SubscriptionAPI();
            string dt = SubscriptionAPIObj.GetTimeRequest();

            Hash = strToHash;
            Hash = hex_hmac_sha1(strMerchantKey, Hash);

            return Hash;
        }
        public static string HashToken(string strMerchantPassword, string strMerchantKey)
        {
            string Token = null;

            SubscriptionAPI SubscriptionAPIObj = new SubscriptionAPI();
            string dt = SubscriptionAPIObj.GetTimeRequest();

            //// Password Digest
            //   -> PassWord|YYYYMMDD|HHMM
            Token = strMerchantPassword + "|" + dt;
            Token = hex_hmac_sha1(strMerchantKey, Token);

            return Token;
        }