使用C#实现SSLSocket加密通讯

SSL Socket通讯是对socket的扩展，增加Socket通讯的数据安全性，SSL认证分为单向和双向认证。单向认证只认证服务器端的合法性而不认证客户端的合法性。双向认证是同时认证服务端和客户端。下面我分别说说使用C#实现单向认证和双向认证的过程，并用代码实现。

一、单向认证

第1步：准备一个数字证书，可以使用如下脚本生成
先进入到vs2005的命令行状态，即:
开始–>程序–>Microsoft Visual Studio 2005–>Visual Studio Tools–>Visual Studio 2005 命令提示
键入: makecert -r -pe -n “CN=TestServer” -ss Root -sky exchange
说明：上面的指令将在创建一个受信任的根证书，
第2步创建服务器端程序，代码如下：
using System;
using System.ServiceModel;
using System.Net;
using System.Net.Sockets;
using System.Net.Security;
using System.Text;
using System.Security.Authentication;
using System.Security.Cryptography.X509Certificates;
using System.IdentityModel.Tokens;
using System.IdentityModel.Selectors;

namespace ConsoleApp
{
public class Program
{
static X509Certificate serverCertificate = null;

    public static void RunServer(){TcpListener listener = new TcpListener(IPAddress.Parse("192.168.1.25"), 901);listener.Start();while (true){try{Console.WriteLine("Waiting for a client to connect...");TcpClient client = listener.AcceptTcpClient();ProcessClient(client);}catch{}}}

static void ProcessClient(TcpClient client)
{SslStream sslStream = new SslStream(client.GetStream(), false);try{sslStream.AuthenticateAsServer(serverCertificate, false, SslProtocols.Tls, true);DisplaySecurityLevel(sslStream);DisplaySecurityServices(sslStream);DisplayCertificateInformation(sslStream);DisplayStreamProperties(sslStream);sslStream.ReadTimeout = 5000;sslStream.WriteTimeout = 5000;byte[] message = Encoding.UTF8.GetBytes("Hello from the server.");Console.WriteLine("Sending hello message.");sslStream.Write(message);Console.WriteLine("Waiting for client message...");while (true){string messageData = ReadMessage(sslStream);Console.WriteLine("Received: {0}", messageData);if (messageData.ToUpper() == "EXIT")break;} }catch (AuthenticationException e){Console.WriteLine("Exception: {0}", e.Message);if (e.InnerException != null){Console.WriteLine("Inner exception: {0}", e.InnerException.Message);}Console.WriteLine("Authentication failed - closing the connection.");sslStream.Close();client.Close();return;}finally{sslStream.Close();client.Close();}
}static string ReadMessage(SslStream sslStream)
{byte[] buffer = new byte[2048];StringBuilder messageData = new StringBuilder();int bytes = -1;do{bytes = sslStream.Read(buffer, 0, buffer.Length);Decoder decoder = Encoding.UTF8.GetDecoder();char[] chars = new char[decoder.GetCharCount(buffer, 0, bytes)];decoder.GetChars(buffer, 0, bytes, chars, 0);messageData.Append(chars);if (messageData.ToString().IndexOf("") != -1){break;}}while (bytes != 0);return messageData.ToString();
}static void DisplaySecurityLevel(SslStream stream)
{Console.WriteLine("Cipher: {0} strength {1}", stream.CipherAlgorithm, stream.CipherStrength);Console.WriteLine("Hash: {0} strength {1}", stream.HashAlgorithm, stream.HashStrength);Console.WriteLine("Key exchange: {0} strength {1}", stream.KeyExchangeAlgorithm, stream.KeyExchangeStrength);Console.WriteLine("Protocol: {0}", stream.SslProtocol);
}static void DisplaySecurityServices(SslStream stream)
{Console.WriteLine("Is authenticated: {0} as server? {1}", stream.IsAuthenticated, stream.IsServer);Console.WriteLine("IsSigned: {0}", stream.IsSigned);Console.WriteLine("Is Encrypted: {0}", stream.IsEncrypted);
}static void DisplayStreamProperties(SslStream stream)
{Console.WriteLine("Can read: {0}, write {1}", stream.CanRead, stream.CanWrite);Console.WriteLine("Can timeout: {0}", stream.CanTimeout);
}static void DisplayCertificateInformation(SslStream stream)
{Console.WriteLine("Certificate revocation list checked: {0}", stream.CheckCertRevocationStatus);X509Certificate localCertificate = stream.LocalCertificate;if (stream.LocalCertificate != null){Console.WriteLine("Local cert was issued to {0} and is valid from {1} until {2}.",localCertificate.Subject,localCertificate.GetEffectiveDateString(),localCertificate.GetExpirationDateString());}else{Console.WriteLine("Local certificate is null.");}X509Certificate remoteCertificate = stream.RemoteCertificate;if (stream.RemoteCertificate != null){Console.WriteLine("Remote cert was issued to {0} and is valid from {1} until {2}.",remoteCertificate.Subject,remoteCertificate.GetEffectiveDateString(),remoteCertificate.GetExpirationDateString());}else{Console.WriteLine("Remote certificate is null.");}
}private static void DisplayUsage()
{Console.WriteLine("To start the server specify:");Console.WriteLine("serverSync certificateFile.cer");
}public static void Main(string[] args)
{try{X509Store store = new X509Store(StoreName.Root);store.Open(OpenFlags.ReadWrite);// 检索证书 X509Certificate2Collection certs = store.Certificates.Find(X509FindType.FindBySubjectName, "TestServer", false); // vaildOnly = true时搜索无结果。if (certs.Count == 0) return;serverCertificate = certs[0];RunServer();store.Close(); // 关闭存储区。}catch (Exception ex){Console.WriteLine(ex.Message);}Console.ReadLine();
}

}

}
第3步，创建客户端代码
namespace ConsoleAppClient
{
using System;
using System.Collections;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Authentication;
using System.Text;
using System.Security.Cryptography.X509Certificates;

namespace Examples.System.Net
{public class SslTcpClient{private static Hashtable certificateErrors = new Hashtable();// The following method is invoked by the RemoteCertificateValidationDelegate.public static bool ValidateServerCertificate(object sender,X509Certificate certificate,X509Chain chain,SslPolicyErrors sslPolicyErrors){if (sslPolicyErrors == SslPolicyErrors.None)return true;Console.WriteLine("Certificate error: {0}", sslPolicyErrors);// Do not allow this client to communicate with unauthenticated servers.return false;}

    public static void RunClient(string machineName){// Create a TCP/IP client socket.// machineName is the host running the server application.TcpClient client = new TcpClient(machineName, 901);Console.WriteLine("Client connected.");// Create an SSL stream that will close the client's stream.SslStream sslStream = new SslStream(client.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);try{sslStream.AuthenticateAsClient("TestServer");}catch (AuthenticationException e){Console.WriteLine("Exception: {0}", e.Message);if (e.InnerException != null){Console.WriteLine("Inner exception: {0}", e.InnerException.Message);}Console.WriteLine("Authentication failed - closing the connection.");client.Close();return;}// Encode a test message into a byte array.// Signal the end of the message using the "&lt;EOF&gt;".byte[] messsage = Encoding.UTF8.GetBytes("Hello from the client.&lt;EOF&gt;");// Send hello message to the server. sslStream.Write(messsage);sslStream.Flush();// Read message from the server.string serverMessage = ReadMessage(sslStream);Console.WriteLine("Server says: {0}", serverMessage);messsage = Encoding.UTF8.GetBytes("exit");sslStream.Write(messsage);sslStream.Flush();// Close the client connection.client.Close();Console.WriteLine("Client closed.");}static string ReadMessage(SslStream sslStream){// Read the  message sent by the server.// The end of the message is signaled using the// "&lt;EOF&gt;" marker.byte[] buffer = new byte[2048];StringBuilder messageData = new StringBuilder();int bytes = -1;do{bytes = sslStream.Read(buffer, 0, buffer.Length);// Use Decoder class to convert from bytes to UTF8// in case a character spans two buffers.Decoder decoder = Encoding.UTF8.GetDecoder();char[] chars = new char[decoder.GetCharCount(buffer, 0, bytes)];decoder.GetChars(buffer, 0, bytes, chars, 0);messageData.Append(chars);// Check for EOF.if (messageData.ToString().IndexOf("&lt;EOF&gt;") != -1){break;}} while (bytes != 0);return messageData.ToString();}private static void DisplayUsage(){Console.WriteLine("To start the client specify:");Console.WriteLine("clientSync machineName [serverName]");Environment.Exit(1);}public static void Main(string[] args){string machineName = null;machineName = "192.168.1.25";try{RunClient(machineName);}catch (Exception ex){Console.WriteLine(ex.Message);}Console.ReadLine();}
}

}

}
运行效果如下图：
导致通讯失败可能问题如下：
1）证书没有导入到受信任的根证书列表中；2）证书失效；3）客户端在使用AuthenticateAsClient注册时没有正确使用服务器端证书名称。

二、双向认证

第1步：创建所需证书，服务器端所需证书同单向认证中的创建过程
先进入到vs2005的命令行状态，即:
开始–>程序–>Microsoft Visual Studio 2005–>Visual Studio Tools–>Visual Studio 2005 命令提示
键入:
makecert -r -pe -n “CN=TestClient” -ss Root -sky exchange
第2步：创建服务端程序
服务端的程序同单向认证的服务器端代码
第3步：创建客户端程序
namespace ConsoleAppClient
{
using System;
using System.Collections;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Authentication;
using System.Text;
using System.Security.Cryptography.X509Certificates;

namespace Examples.System.Net
{public class SslTcpClient{private static Hashtable certificateErrors = new Hashtable();// The following method is invoked by the RemoteCertificateValidationDelegate.public static bool ValidateServerCertificate(object sender,X509Certificate certificate,X509Chain chain,SslPolicyErrors sslPolicyErrors){if (sslPolicyErrors == SslPolicyErrors.None)return true;

        Console.WriteLine("Certificate error: {0}", sslPolicyErrors);// Do not allow this client to communicate with unauthenticated servers.return false;}public static void RunClient(string machineName){// Create a TCP/IP client socket.// machineName is the host running the server application.TcpClient client = new TcpClient(machineName, 901);Console.WriteLine("Client connected.");// Create an SSL stream that will close the client's stream.SslStream sslStream = new SslStream(client.GetStream(), false, new RemoteCertificateValidationCallback(ValidateServerCertificate), null);// The server name must match the name on the server certificate.X509Store store = new X509Store(StoreName.Root);store.Open(OpenFlags.ReadWrite);检索证书 X509Certificate2Collection certs = store.Certificates.Find(X509FindType.FindBySubjectName, "TestClient", false);                try{sslStream.AuthenticateAsClient("TestServer", certs, SslProtocols.Tls, false);}catch (AuthenticationException e){Console.WriteLine("Exception: {0}", e.Message);if (e.InnerException != null){Console.WriteLine("Inner exception: {0}", e.InnerException.Message);}Console.WriteLine("Authentication failed - closing the connection.");client.Close();return;}// Encode a test message into a byte array.// Signal the end of the message using the "&lt;EOF&gt;".byte[] messsage = Encoding.UTF8.GetBytes("Hello from the client.&lt;EOF&gt;");// Send hello message to the server. sslStream.Write(messsage);sslStream.Flush();// Read message from the server.string serverMessage = ReadMessage(sslStream);Console.WriteLine("Server says: {0}", serverMessage);messsage = Encoding.UTF8.GetBytes("exit");sslStream.Write(messsage);sslStream.Flush();// Close the client connection.client.Close();Console.WriteLine("Client closed.");}static string ReadMessage(SslStream sslStream){// Read the  message sent by the server.// The end of the message is signaled using the// "&lt;EOF&gt;" marker.byte[] buffer = new byte[2048];StringBuilder messageData = new StringBuilder();int bytes = -1;do{bytes = sslStream.Read(buffer, 0, buffer.Length);// Use Decoder class to convert from bytes to UTF8// in case a character spans two buffers.Decoder decoder = Encoding.UTF8.GetDecoder();char[] chars = new char[decoder.GetCharCount(buffer, 0, bytes)];decoder.GetChars(buffer, 0, bytes, chars, 0);messageData.Append(chars);// Check for EOF.if (messageData.ToString().IndexOf("&lt;EOF&gt;") != -1){break;}} while (bytes != 0);return messageData.ToString();}private static void DisplayUsage(){Console.WriteLine("To start the client specify:");Console.WriteLine("clientSync machineName [serverName]");Environment.Exit(1);}public static void Main(string[] args){string machineName = null;machineName = "192.168.1.25";try{RunClient(machineName);}catch (Exception ex){Console.WriteLine(ex.Message);}Console.ReadLine();}
}

}