使用c＃中的私钥对数据进行签名

我需要使用一个私钥使用算法SHA1RSA，Rsa密钥长度2048和64基本编码来签署一些数据。我的代码是这样的

string sPayload = ""; HttpWebRequest httpWebRequest = (HttpWebRequest)WebRequest.Create("URI"); httpWebRequest.ContentType = "application/json; charset=utf-8"; httpWebRequest.Method = WebRequestMethods.Http.Post; using (StreamWriter streamWriter = new StreamWriter(httpWebRequest.GetRequestStream())) { sPayload = "{"id":"14123213213"," + ""uid":"teller"," + ""pwd":"abc123"," + ""apiKey":"2343243"," + ""agentRefNo":"234324324"}"; httpWebRequest.Headers.Add("SIGNATURE", Convert.ToBase64String(new System.Security.Cryptography.SHA1CryptoServiceProvider().ComputeHash(Encoding.ASCII.GetBytes(sPayload)))); streamWriter.Write(sPayload); streamWriter.Flush(); streamWriter.Close(); } System.Net.ServicePointManager.Expect100Continue = false; HttpWebResponse httpResponse = (HttpWebResponse)httpWebRequest.GetResponse(); using (StreamReader streamReader = new StreamReader(httpResponse.GetResponseStream())) { string result = streamReader.ReadToEnd(); } 

在标题名称签名中，我需要使用私钥传递签名数据（sPayload）。但是使用上面的代码，错误从第三方获得“无效签名”，并且我不确定加密部分是否正确。

 httpWebRequest.Headers.Add("SIGNATURE", Convert.ToBase64String(new System.Security.Cryptography.SHA1CryptoServiceProvider().ComputeHash(Encoding.ASCII.GetBytes(sPayload)))); 

第三方提供了一个证书（证书，sha1）和密钥。我应该将其引用到代码中吗？

 using (RSA rsa = cert.GetRSAPrivateKey()) { return rsa.SignData(sPayload, HashAlgorithmName.SHA1, RSASignaturePadding.Pkcs1); } 

 byte[] hash; byte[] signature; using (HashAlgorithm hasher = SHA1.Create()) using (RSA rsa = cert.GetRSAPrivateKey()) { hash = hasher.ComputeHash(sPayload); signature = rsa.SignHash(hash, HashAlgorithmName.SHA1, RSASignaturePadding.Pkcs1); }