c# .net framework 实现微信支付v3 h5支付 签名 验签

接口文档：微信支付-开发者文档 (qq.com)

          public const string transactions_url = "https://api.mch.weixin.qq.com/v3/pay/transactions/h5";         public static string certPath = AppDomain.CurrentDomain.BaseDirectory + @"certapiclient_cert.p12";         public static string certificatesPath = AppDomain.CurrentDomain.BaseDirectory + @"certcertificates_cert.pem"; // 回调解密证书 根据接口获取后 保存为 pem 后缀  我请求后自己手动保存的。没写代码去保存         private static string certPassword = "888888888"; //.p12 的证书密码         public string BuildAuth(string mchid, string serial_no, string method, string uri, string body)         {         var timestamp = DateTimeOffset.Now.ToUnixTimeSeconds();         string nonce = Guid.NewGuid().ToString();         //构造签名串         //HTTP请求方法n + URLn + 请求时间戳n + 请求随机串n + 请求报文主体n         string message = method + "n" + uri + "n" + timestamp + "n" + nonce + "n" + body + "n";         string signature = GenerateSignature(message);          //发起请求的商户（包括直连商户、服务商或渠道商）的商户号 mchid         //商户API证书序列号serial_no，用于声明所使用的证书         //请求随机串nonce_str         //时间戳timestamp         //签名值signature         return "mchid="" + mchid + "",nonce_str="" + nonce + "",timestamp="" + timestamp + "",serial_no="" + serial_no + "",signature="" + signature + """;         }           /// <summary>         /// 生成签名         /// </summary>         /// <param name="message"></param>         /// <returns></returns>         public static string GenerateSignature(string message)         {         X509Certificate2 cert = new X509Certificate2(certPath, certPassword, X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable);         RSA PrivateKey = cert.GetRSAPrivateKey();         byte[] dataBytes = Encoding.UTF8.GetBytes(message);         byte[] signatureBytes = PrivateKey.SignData(dataBytes, HashAlgorithmName.SHA256, RSASignaturePadding.Pkcs1);         return Convert.ToBase64String(signatureBytes);         }           /// <summary>         /// 验证回调签名         /// </summary>         /// <param name="signature"></param>         /// <param name="timestamp"></param>         /// <param name="nonce"></param>         /// <param name="body"></param>         /// <returns></returns>         public static bool VerifySignature(string signature, string timestamp, string nonce, string body)         {         //应答时间戳n         //应答随机串n         //应答报文主体n         X509Certificate2 wechatCert = new X509Certificate2(certificatesPath); //, X509KeyStorageFlags.MachineKeySet | X509KeyStorageFlags.PersistKeySet | X509KeyStorageFlags.Exportable         string combinedString = string.Format("{0}n{1}n{2}n", timestamp, nonce, body);         byte[] buff = Encoding.UTF8.GetBytes(combinedString);         var rsaPar = wechatCert.GetRSAPublicKey().ExportParameters(false);         var rsa = new RSACryptoServiceProvider();         rsa.ImportParameters(rsaPar);         return rsa.VerifyData(buff, CryptoConfig.MapNameToOID("SHA256"), Convert.FromBase64String(signature));         }           #region 加密解密          public static string AesGcmDecrypt(string associatedData, string nonce, string ciphertext, string apikey)         {         GcmBlockCipher gcmBlockCipher = new GcmBlockCipher(new AesEngine());         AeadParameters aeadParameters = new AeadParameters(         new KeyParameter(Encoding.UTF8.GetBytes(apikey)),         128,         Encoding.UTF8.GetBytes(nonce),         Encoding.UTF8.GetBytes(associatedData));         gcmBlockCipher.Init(false, aeadParameters);          byte[] data = Convert.FromBase64String(ciphertext);         byte[] plaintext = new byte[gcmBlockCipher.GetOutputSize(data.Length)];         int length = gcmBlockCipher.ProcessBytes(data, 0, data.Length, plaintext, 0);         gcmBlockCipher.DoFinal(plaintext, length);         return Encoding.UTF8.GetString(plaintext);         }         #endregion                  

  遇到的问题有

  1、签名老验证不过去：

  
  生成的签名老验证不过    n 不要加转义符

  2、 发送的请求老是400  使用工具请求正常。代码不行。
  UserAgent = "m.cnblogs.com/WebRequest"; 
  不要留空就行 网址可填自己的。

  3、回调解密的证书是自己获取的。可以获取后自己保存为后缀 .pem的证书文件
   获取平台证书列表-文档中心-微信支付商户平台 (qq.com)

  4、请求到h5_url 后可以在后面拼接指定跳转链接  https://wx.tenpay.com/cgi-bin/mmpayweb-bin/checkmweb?prepay_id=wx2916263004719461949c84457c735b0000&package=2150917749&redirect_url=System.Web.HttpUtility.UrlEncode("https://www.cnblogs.com/MIMU86")

  5、苹果手机不是默认浏览器会跳到默认浏览器 无解