编辑“︁C Sharp 安全通信”︁（章节）

== SSL/TLS基础 ==
SSL（Secure Sockets Layer）及其继任者TLS（Transport Layer Security）是安全通信的基础协议。在C#中，可以通过`SslStream`类实现基于SSL/TLS的安全通信。

<mermaid>
sequenceDiagram
    Client->>Server: ClientHello
    Server->>Client: ServerHello + Certificate
    Client->>Server: Key Exchange
    Server->>Client: Finished
    Client->>Server: Encrypted Data
</mermaid>

=== 基本示例 ===
以下是一个使用`SslStream`的简单服务器和客户端实现：

'''服务器端代码：'''
<syntaxhighlight lang="csharp">
using System.Net;
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Cryptography.X509Certificates;

var listener = new TcpListener(IPAddress.Any, 12345);
listener.Start();

var client = listener.AcceptTcpClient();
var stream = new SslStream(client.GetStream(), false);
var cert = new X509Certificate2("server.pfx", "password");
stream.AuthenticateAsServer(cert);

// 读写加密数据
var reader = new StreamReader(stream);
var writer = new StreamWriter(stream);
writer.WriteLine("Secure hello!");
writer.Flush();
</syntaxhighlight>

'''客户端代码：'''
<syntaxhighlight lang="csharp">
using System.Net.Security;
using System.Net.Sockets;
using System.Security.Cryptography.X509Certificates;

var client = new TcpClient("localhost", 12345);
var stream = new SslStream(client.GetStream(), false, 
    (sender, certificate, chain, errors) => true); // 简化证书验证

stream.AuthenticateAsClient("localhost");

var reader = new StreamReader(stream);
Console.WriteLine(reader.ReadLine()); // 输出: Secure hello!
</syntaxhighlight>