net版本 微信现金红包接口调用的时候，老是出现签名错误

创建签名  所使用到的几个方法

    

             string url = "https://api.mch.weixin.qq.com/mmpaymkttransfers/sendredpack";
                //随机字符串
                string nonce_str = CreateRandomCode(32);
                //商户号
                string mch_id = "111111111111";
                //商户订单号
                string mch_billno = mch_id + DateTime.Now.ToString("yyyyMMdd") + Rand();//自己生成把
                //公众账号appid
                string wxappid = "222222222222222222222";
                //提供方名称
                string nick_name = "提供方名称";
                //商户名称
                string send_name = "商户名称";
                //用户openid
                string re_openid = s.open_id;
                //付款金额         这里要注意 提现是 1 - 200元 ，但是这里的单位是  “分”
                string total_amount = (money * 100).ToString();
                //最小红包金额
                string min_value = (money * 100).ToString();
                //最大红包金额
                string max_value = (money * 100).ToString();
                //红包发放总人数
                string total_num = "1";
                //红包祝福语
                string wishing = "活动名称";
                string client_ip = "192.168.10.0";
                //活动名称
                string act_name = "活动名称";
                //备注
                string remark = "提现问题,请联系客服人员";

 

  Dictionary<string, string> parameters = new Dictionary<string, string>();
                parameters.Add("act_name", act_name);
                parameters.Add("client_ip", client_ip);
                parameters.Add("min_value", min_value);
                parameters.Add("max_value", max_value);
                parameters.Add("mch_billno", mch_billno);
                parameters.Add("mch_id", mch_id);
                parameters.Add("nonce_str", nonce_str);
                parameters.Add("nick_name", nick_name);
                parameters.Add("re_openid", re_openid);
                parameters.Add("remark", remark);
                parameters.Add("send_name", send_name);
                parameters.Add("total_num", total_num);
                parameters.Add("total_amount", total_amount);
                parameters.Add("wishing", wishing);
                parameters.Add("wxappid", wxappid);
                //生成签名
                string sign = CreateSignString(parameters, "自己的 API密钥 ");

提供一个 加密的方法 CreateSignString

 static string CreateSignString(Dictionary<string, string> parameters, string paySecret)
        {
            foreach (var key in parameters.Keys.Where(key => string.IsNullOrEmpty(parameters[key])))
            {
                parameters.Remove(key);
            }

            //第一步，设所有収送戒者接收到的数据为集合 M，将集合 M 内非空参数值的参数按照参数名ASCII码从小到大排序（字典序），
            //使用URL键值对的格式（即key1=value1&key2=value2…）拼接成字符串 stringA。
            //特别注意以下重要规则：
            //1.参数名 ASCII 码从小到大排序（字典序） ；
            //2.如果参数的值为空不参与签名；
            //3.参数名区分大小写；
            //4.验证调用返回戒微信主劢通知签名时，传送的 sign 参数不参与签名，将生成的签名与该 sign 值作校验。
            var keyArray = parameters.Keys.ToArray();
            Array.Sort(keyArray);
            var keyString = keyArray.Aggregate("", (current, t) => current + (t + "=" + parameters[t] + "&"));

            //第二步，在 stringA 最后拼接上 key=商户支付密钥得到 stringSignTemp 字符串，
            //并对 stringSignTemp 进行 MD5 运算，再将得到的字符串所有字符转换为大写，得到 sign的值 signValue
            keyString += "key=" + paySecret;

            return toMD5(keyString).ToUpper();
        }
        public static string toMD5(string str)
        {
            byte[] md5Bytes = Encoding.UTF8.GetBytes(str);
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] cryptString = md5.ComputeHash(md5Bytes);

            int len;
            string temp = String.Empty;

            len = cryptString.Length;

            for (int i = 0; i < len; i++)
            {
                temp += cryptString[i].ToString("X2");
            }
            return temp;
        }

随机数 

 public string CreateRandomCode(int codeCount, int flag = 0)
        {
            string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,W,X,Y,Z";
            if (flag == 1)
            {
                allChar = "0,1,2,3,4,5,6,7,8,9";
            }

            //里面的字符你可以自己加啦      
            string[] allCharArray = allChar.Split(',');
            string randomCode = "";
            int temp = -1;
            Random random = new Random();
            for (int i = 0; i < codeCount; i++)
            {
                if (temp != -1)
                {
                    random = new Random(i * temp * (int)DateTime.Now.Ticks);
                }
                int t = random.Next(35);
                if (temp == t)
                {
                    return CreateRandomCode(codeCount);
                }
                temp = t;
                randomCode += allCharArray[temp];
            }
            return randomCode;
        }
        public string Rand()
        {
            string all = "0,1,2,3,4,5,6,7,8,9";
            string[] allChar = all.Split(',');
            string result = "";
            Random rand = new Random();
            for (int i = 0; i < 10; i++)
            { result += allChar[rand.Next(9)]; }
            return result;
        }

请求api 带证书的方法

  public string OpenReadWithHttps(string URL, string strPostdata, string strEncoding)
        {
            try
            {
                Encoding encoding = Encoding.UTF8;

                string cert = @"D:\apiclient_cert.p12";
                string password = "  这里是填写的是 微信支付商户号   ";

                ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
                X509Certificate cer = new X509Certificate(cert, password);
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(URL);
                request.ClientCertificates.Add(cer);


                request.Method = "post";

                request.Accept = "text/html, application/xhtml+xml, */*";

                request.ContentType = "application/x-www-form-urlencoded";


                byte[] buffer = encoding.GetBytes(strPostdata);

                request.ContentLength = buffer.Length;

                request.GetRequestStream().Write(buffer, 0, buffer.Length);

                HttpWebResponse response = (HttpWebResponse)request.GetResponse();

                using (StreamReader reader = new StreamReader(response.GetResponseStream(), System.Text.Encoding.GetEncoding(strEncoding)))
                {
                    return reader.ReadToEnd();
                }
            }
            catch (Exception e)
            {
                 
                return "";
            }

        }