SSL communication between Java and C# applications

Question

My goal is to make a secure communication between a Java server and client written in C#.

java server code:

  System.setProperty("javax.net.ssl.keyStore","cert/mySrvKeystore");
  System.setProperty("javax.net.ssl.keyStorePassword","myPassword");

  SSLServerSocketFactory sslserversocketfactory =
            (SSLServerSocketFactory) SSLServerSocketFactory.getDefault();
  SSLServerSocket sslserversocket =  = (SSLServerSocket) sslserversocketfactory.createServerSocket(2389);

    while(true) {
    System.err.println("server w8 new connection");
     try {

            SSLSocket sslsocket = (SSLSocket) sslserversocket.accept();
            //sslsocket.startHandshake();

            in = sslsocket.getInputStream();
            out = sslsocket.getOutputStream();
            out.flush();

            String response = new String(receiveMessage());
            while (response != "end") {
                System.out.println("Server recv="+response);
                response = new String(receiveMessage());
                sendMessage(("echo="+response).getBytes());
            }
        } catch (Exception exception) {
            exception.printStackTrace();
        }
    }

and client written in c# :

        client = new TcpClient() { SendTimeout = 5000, ReceiveTimeout = 5000 };
        IPEndPoint serverEndPoint = new IPEndPoint(IPAddress.Parse(host), port);

        client.Connect(serverEndPoint);
        client.NoDelay = true;
        Console.WriteLine("Client connected.");

        // Create an SSL stream that will close the client's stream.
        SslStream sslStream = new SslStream(client.GetStream(), false, ValidateServerCertificate, null);
        // The server name must match the name on the server certificate.
        try
        {
            sslStream.AuthenticateAsClient("someName");
        }
        catch (AuthenticationException error)
        {
            Console.WriteLine("Exception: {0}", error.Message);
            if (error.InnerException != null)
            {
                Console.WriteLine("Inner exception: {0}", error.InnerException.Message);
            }
            Console.WriteLine("Authentication failed - closing the connection.");
            client.Close();
            return;
        }

        ASCIIEncoding ascii = new ASCIIEncoding();
        SendData(ascii.GetBytes("Hello World"));     

and

    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;
    }

and i get the following errors: in c#

 A first chance exception of type "System.Security.Authentication.AuthenticationException" occurred in System.dll
 Certificate error: RemoteCertificateChainErrors
 Exception: The remote certificate is invalid according to the validation procedure.
 Authentication failed - closing the connection.

I know that the issue can be the fact that i use different types of certificates, but i don't know how to make a standard sslServerSocket with X509Certificate in java. Can some one help me, with good example, or some advice how can i reach my goal ?

PS I was looking to bouncycastle library, causes it has both java, and c# implementation, but i would like to use standard libraries, and built-in functionality of the languages.

Answer 1

From your example, it doesn't look like you need to generate your certificate and private key programmatically. You can generate a certificate in your server keystore with keytool :

keytool -genkey -alias myalias -keystore mykeystore.jks -dname "CN=www.example.com"

Or better, with the SAN extension too, if you're using Java 7's keytool :

keytool -genkey -alias myalias -keystore mykeystore.jks -dname "CN=www.example.com" -ext san=dns:www.example.com

Here, www.example.com is the host name as seen by the client. You can add other things in the Subject DN ( dname ), but make sure the CN is the host name.

Once it's generated, export your self-signed certificate using:

keytool -export myservercert.crt -alias myalias -keystore mykeystore.jks

You should then be able to import it as a trusted certificate in your Windows certificate store from use from C#.