[转]如何借助 TLS/SSL 确保套接字连接的安全（使用 C#/VB/C++ 和 XAML 的 Windows 应用商店应用）

using Windows.Networking;
using Windows.Networking.Sockets;


    // Define some variables and set values
    StreamSocket clientSocket = new StreamSocket();
 
    HostName serverHost = new HostName("www.contoso.com");
    string serverServiceName = "https";

    // For simplicity, the sample omits implementation of the
    // NotifyUser method used to display status and error messages 

    // Try to connect to contoso using HTTPS (port 443)
    try {

        // Call ConnectAsync method with SSL
        await clientSocket.ConnectAsync(serverHost, serverServiceName, SocketProtectionLevel.Ssl);

        NotifyUser("Connected");
    }
    catch (Exception exception) {
        // If this is an unknown status it means that the error is fatal and retry will likely fail.
        if (SocketError.GetStatus(exception.HResult) == SocketErrorStatus.Unknown) {
            throw;
        }

        NotifyUser("Connect failed with error: " + exception.Message);
        // Could retry the connection, but for this simple example
        // just close the socket.

        clientSocket.Dispose();
        clientSocket = null; 
    }
       
    // Add code to send and receive data using the clientSocket
    // and then close the clientSocket

using Windows.Networking;
using Windows.Networking.Sockets;
using Windows.Storage.Streams;

    // Define some variables and set values
    StreamSocket clientSocket = new StreamSocket();
 
    HostName serverHost = new HostName("www.contoso.com");
    string serverServiceName = "http";

    // For simplicity, the sample omits implementation of the
    // NotifyUser method used to display status and error messages 

    // Try to connect to contoso using HTTP (port 80)
    try {
        // Call ConnectAsync method with a plain socket
        await clientSocket.ConnectAsync(serverHost, serverServiceName, SocketProtectionLevel.PlainSocket);

        NotifyUser("Connected");

    }
    catch (Exception exception) {
        // If this is an unknown status it means that the error is fatal and retry will likely fail.
        if (SocketError.GetStatus(exception.HResult) == SocketErrorStatus.Unknown) {
            throw;
        }

        NotifyUser("Connect failed with error: " + exception.Message, NotifyType.ErrorMessage);
        // Could retry the connection, but for this simple example
        // just close the socket.

        clientSocket.Dispose();
        clientSocket = null; 
        return;
    }

    // Now try to sent some data
    DataWriter writer = new DataWriter(clientSocket.OutputStream);
    string hello = "Hello World ? ";
    Int32 len = (int) writer.MeasureString(hello); // Gets the UTF-8 string length.
    writer.WriteInt32(len);
    writer.WriteString(hello);
    NotifyUser("Client: sending hello");

    try {
        // Call StoreAsync method to store the hello message
        await writer.StoreAsync();

        NotifyUser("Client: sent data");

        writer.DetachStream(); // Detach stream, if not, DataWriter destructor will close it.
    }
    catch (Exception exception) {
        NotifyUser("Store failed with error: " + exception.Message);
        // Could retry the store, but for this simple example
            // just close the socket.

            clientSocket.Dispose();
            clientSocket = null; 
            return;
    }

    // Now upgrade the client to use SSL
    try {
        // Try to upgrade to SSL
        await clientSocket.UpgradeToSslAsync(SocketProtectionLevel.Ssl, serverHost);

        NotifyUser("Client: upgrade to SSL completed");
           
        // Add code to send and receive data 
        // The close clientSocket when done
    }
    catch (Exception exception) {
        // If this is an unknown status it means that the error is fatal and retry will likely fail.
        if (SocketError.GetStatus(exception.HResult) == SocketErrorStatus.Unknown) {
            throw;
        }

        NotifyUser("Upgrade to SSL failed with error: " + exception.Message);

        clientSocket.Dispose();
        clientSocket = null; 
        return;
    }