AW.Pay.Core.MD5Helper.Sign C# (CSharp) Method

        public static string Sign(string prestr, string _input_charset)
        {
            StringBuilder sb = new StringBuilder(32);
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] t = md5.ComputeHash(Encoding.GetEncoding(_input_charset).GetBytes(prestr));
            for (int i = 0; i < t.Length; i++)
            {
                sb.Append(t[i].ToString("x").PadLeft(2, '0'));
            }

            return sb.ToString();
        }
    }

        private string BuildRequest(string orderNo, string productName, int totalFee, string customerIP, EnumWePayTradeType tradeType)
        {
            SortedDictionary <string, string> dicParam = CreateParam(orderNo, productName, totalFee, customerIP, tradeType);

            string signString = CreateURLParamString(dicParam);
            string key        = tradeType == EnumWePayTradeType.APP ? WepayConfig.WEPAY_APP_KEY : WepayConfig.WEPAY_WEB_KEY;
            string preString  = signString + "&key=" + key;
            string sign       = MD5Helper.Sign(preString, WepayConfig.WEPAY_CHARTSET).ToUpper();

            dicParam.Add("sign", sign);

            return(BuildForm(dicParam));
        }