SslProtocols Enumeration

 

Defines the possible versions of SslProtocols.

This enumeration has a FlagsAttribute attribute that allows a bitwise combination of its member values.

Namespace:   System.Security.Authentication
Assembly:  System (in System.dll)

[FlagsAttribute]
public enum class SslProtocols

Member nameDescription
Default

Specifies that either Secure Sockets Layer (SSL) 3.0 or Transport Layer Security (TLS) 1.0 are acceptable for secure communications

None

No SSL protocol is specified.

Ssl2

Specifies the SSL 2.0 protocol. SSL 2.0 has been superseded by the TLS protocol and is provided for backward compatibility only.

Ssl3

Specifies the SSL 3.0 protocol. SSL 3.0 has been superseded by the TLS protocol and is provided for backward compatibility only.

Tls

Specifies the TLS 1.0 security protocol. The TLS protocol is defined in IETF RFC 2246.

Tls11

Specifies the TLS 1.1 security protocol. The TLS protocol is defined in IETF RFC 4346.

Tls12

Specifies the TLS 1.2 security protocol. The TLS protocol is defined in IETF RFC 5246.

The following code example demonstrates creating a TcpClient that uses the SslStream class to communicate with a server.

#using <System.dll>
#using <System.Security.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Globalization;
using namespace System::Net;
using namespace System::Net::Security;
using namespace System::Net::Sockets;
using namespace System::Security::Authentication;
using namespace System::Text;
using namespace System::Security::Cryptography::X509Certificates;
using namespace System::IO;

namespace NlsClientSync
{
    public ref class SslTcpClient
    {
    private:
        static Hashtable^ certificateErrors = gcnew Hashtable;
        // Load a table of errors that might cause 
        // the certificate authentication to fail.
        static void InitializeCertificateErrors()
        {
            certificateErrors->Add(0x800B0101,
                "The certification has expired.");
            certificateErrors->Add(0x800B0104,
                "A path length constraint "
                "in the certification chain has been violated.");
            certificateErrors->Add(0x800B0105,
                "A certificate contains an unknown extension "
                "that is marked critical.");
            certificateErrors->Add(0x800B0107,
                "A parent of a given certificate in fact "
                "did not issue that child certificate.");
            certificateErrors->Add(0x800B0108,
                "A certificate is missing or has an empty value "
                "for a necessary field.");
            certificateErrors->Add(0x800B0109,
                "The certificate root is not trusted.");
            certificateErrors->Add(0x800B010C,
                "The certificate has been revoked.");
            certificateErrors->Add(0x800B010F,
                "The name in the certificate does not not match "
                "the host name requested by the client.");
            certificateErrors->Add(0x800B0111,
                "The certificate was explicitly marked "
                "as untrusted by the user.");
            certificateErrors->Add(0x800B0112,
                "A certification chain processed correctly, "
                "but one of the CA certificates is not trusted.");
            certificateErrors->Add(0x800B0113,
                "The certificate has an invalid policy.");
            certificateErrors->Add(0x800B0114,
                "The certificate name is either not "
                "in the permitted list or is explicitly excluded.");
            certificateErrors->Add(0x80092012,
                "The revocation function was unable to check "
                "revocation for the certificate.");
            certificateErrors->Add(0x80090327,
                "An unknown error occurred while "
                "processing the certificate.");
            certificateErrors->Add(0x80096001,
                "A system-level error occurred "
                "while verifying trust.");
            certificateErrors->Add(0x80096002,
                "The certificate for the signer of the message "
                "is invalid or not found.");
            certificateErrors->Add(0x80096003,
                "One of the counter signatures was invalid.");
            certificateErrors->Add(0x80096004,
                "The signature of the certificate "
                "cannot be verified.");
            certificateErrors->Add(0x80096005,
                "The time stamp signature or certificate "
                "could not be verified or is malformed.");
            certificateErrors->Add(0x80096010,
                "The digital signature of the object "
                "was not verified.");
            certificateErrors->Add(0x80096019,
                "The basic constraint extension of a certificate "
                "has not been observed.");
        }

        static String^ CertificateErrorDescription(UInt32 problem)
        {
            // Initialize the error message dictionary 
            // if it is not yet available.
            if (certificateErrors->Count == 0)
            {
                InitializeCertificateErrors();
            }

            String^ description = safe_cast<String^>(
                certificateErrors[problem]);
            if (description == nullptr)
            {
                description = String::Format(
                    CultureInfo::CurrentCulture,
                    "Unknown certificate error - 0x{0:x8}",
                    problem);
            }

            return description;
        }

    public:
        // The following method is invoked 
        // by the CertificateValidationDelegate.
    static bool ValidateServerCertificate(
            Object^ sender,
            X509Certificate^ certificate,
            X509Chain^ chain,
            SslPolicyErrors sslPolicyErrors)
        {

            Console::WriteLine("Validating the server certificate.");
            if (sslPolicyErrors == SslPolicyErrors::None)
                return true;

            Console::WriteLine("Certificate error: {0}", sslPolicyErrors);

            // Do not allow this client to communicate with unauthenticated servers.
            return false;
        }

        static void RunClient(String^ machineName, String^ serverName)
        {

            // Create a TCP/IP client socket.
            // machineName is the host running the server application.
            TcpClient^ client = gcnew TcpClient(machineName, 8080);
            Console::WriteLine("Client connected.");

            // Create an SSL stream that will close 
            // the client's stream.
            SslStream^ sslStream = gcnew SslStream(
                client->GetStream(), false,
                gcnew RemoteCertificateValidationCallback(ValidateServerCertificate),
                nullptr);

            // The server name must match the name
            // on the server certificate.
            try
            {
                sslStream->AuthenticateAsClient(serverName);
            }
            catch (AuthenticationException^ ex) 
            {
                Console::WriteLine("Exception: {0}", ex->Message);
                if (ex->InnerException != nullptr)
                {
                    Console::WriteLine("Inner exception: {0}", 
                        ex->InnerException->Message);
                }

                Console::WriteLine("Authentication failed - "
                    "closing the connection.");
                sslStream->Close();
                client->Close();
                return;
            }
            // Encode a test message into a byte array.
            // Signal the end of the message using the "<EOF>".
            array<Byte>^ messsage = Encoding::UTF8->GetBytes(
                "Hello from the client.<EOF>");

            // 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);

            // Close the client connection.
            sslStream->Close();
            client->Close();
            Console::WriteLine("Client closed.");
        }
    private:
        static String^ ReadMessage(SslStream^ sslStream)
        {

            // Read the  message sent by the server.
            // The end of the message is signaled using the
            // "<EOF>" marker.
            array<Byte>^ buffer = gcnew array<Byte>(2048);
            StringBuilder^ messageData = gcnew StringBuilder;
            // Use Decoder class to convert from bytes to UTF8
            // in case a character spans two buffers.
            Encoding^ u8 = Encoding::UTF8;
            Decoder^ decoder = u8->GetDecoder();

            int bytes = -1;
            do
            {
                bytes = sslStream->Read(buffer, 0, buffer->Length);

                array<__wchar_t>^ chars = gcnew array<__wchar_t>(
                    decoder->GetCharCount(buffer, 0, bytes));
                decoder->GetChars(buffer, 0, bytes, chars, 0);
                messageData->Append(chars);

                // Check for EOF.
                if (messageData->ToString()->IndexOf("<EOF>") != -1)
                {
                    break;
                }
            }
            while (bytes != 0);

            return messageData->ToString();
        }
    };
}

int main()
{
    array<String^>^ args = Environment::GetCommandLineArgs();
    String^ serverCertificateName = nullptr;
    String^ machineName = nullptr;
    if (args == nullptr || args->Length < 2)
    {
        Console::WriteLine("To start the client specify:");
        Console::WriteLine("clientSync machineName [serverName]");
        return 1;
    }

    // User can specify the machine name and server name.
    // Server name must match the name on 
    // the server's certificate.
    machineName = args[1];
    if (args->Length < 3)
    {
        serverCertificateName = machineName;
    }
    else
    {
        serverCertificateName = args[2];
    };

    NlsClientSync::SslTcpClient::RunClient(machineName,
        serverCertificateName);

    return 0;
}

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
Return to top
Show: