Bob.cs Source Code (CNG Example)

The Cryptography Next Generation (CNG) secure communication example consists of three console applications: Alice, Bob, and Mallory. The Bob application (Bob.cs file) contains the following code.

using System;                           // Required for the IDisposable interface
using System.Text;                      // Required for the Encoding class

public partial class CNG_SecureCommunicationExample
{
    static int  MyColor = 2;                        // Bob White displays white text
    static int  OtherColor = 4;                     // Alice Green displays green text

    static void Main()
        {
        InitConsole("Bob White", 610, 5);
        string s = "";
        while (true)
            {
            SplashScreen();
            s = AppControl("receive", "BobControlChannel");
            if ("exit" == s)
                break; 
            Run();
            }
        }          // End Main



    static void Run()
    {
        ASCIIEncoding enc = new ASCIIEncoding();

        InitializeOptions();

        System.Threading.Thread.Sleep(200);
        string NewChannelName = ReceiveChannelName();

        string s;

        using (Communicator Bob = new Communicator("client", NewChannelName))
        {
            Display("Hi, I'm Bob White: My sales associate is Alice Green.\n" +
                    "I think she has a new customer contact for me!\n\n");

            if (3 <= Version)
                {
                Display("\nFirst, Alice will publicaly send me a digital signature key.\n");
                Byte[] DSKey = Bob.ChMgr.ReadMessage();                      // Read the message
                Bob.StoreDSKey(DSKey);

                s = enc.GetString(DSKey);
                if (fVerbose)
                    {
                    Display("Here it is:\n\n");
                    Display(s + "\n\n", 4);
                    }
                }


            if (4 <= Version)
                {
                byte[] DSKey;
                using (ChannelManager ChMgr2 = new ChannelManager("client", "PrivateChannel"))
                DSKey = ChMgr2.ReadMessage();
                Bob.StoreDSKey(DSKey);

                Display("\nNow Alice privately sent me a digital signature key. I will use it instead.\n");
                s = enc.GetString(DSKey);
                if (fVerbose)
                    {
                    Display("Here it is:\n\n");
                    Display(s + "\n\n", 4);
                    }
                }

//-------------------------------------------------------------------------------------------------

            if (2 <= Version)
                {
                Display(sep2, 1);
                Display("Now we will exchange our public cryptographic\n" +              // Send and Receive ECDH public keys
                        "keys through a public channel.\n" +
                        "First, Alice will send me her key.\n\nListening...\n");

                if (!Bob.Send_or_Receive_PublicCryptoKey("receive", OtherColor))
                {
                    Console.WriteLine("Press the enter key to continue.");
                    Console.ReadLine();
                    return;
                }

                Display(sep2, 1);
                Display("Next, I will send my public cryptographic key to Alice:\n\nSending...\n");
                Bob.Send_or_Receive_PublicCryptoKey("send", MyColor);
               }

//-------------------------------------------------------------------------------------------------
// Now that all the keys have been transmitted, have a conversation.
            if (1 < Version)
                {
                Display(sep2, 1);
                Display("Now that our keys have been exchanged,\n" +
                       "we can have an encrypted conversation:\n\n", 2);
                Display(sep1, 1);
                }

            Bob.ReceiveMessage();       // Read a message
            Bob.SendMessage("Hi Alice. That is good news. Please send it to me.",true);
            Bob.ReceiveMessage();       // Read a message
            Bob.SendMessage("Thanks, I'll arrange to meet with them.",true);
//-------------------------------------------------------------------------------------------------
            if (Version <= 2)
                Display(sep1,1);

           if (!fVerbose && Version >= 3)
                Display(sep1, 1);

            Display("Would you like to talk to me?\n" +
                    "If yes, go to Alice's window\n" +
                    "and follow the instructions.\n\n",1);
            Display(sep + sep1,1);
            s = "";

            while (true)
                {
                s = Bob.ReceiveMessage();       // Read a message
                if ("" == s)
                    break;
                s = ReadALine(true); 
                if (!Bob.SendMessage(s,false))                // If Alice entered CTRL-C or SYS_CLOSE
                    break;
                if ("" == s)
                    break;
                }
            }        // End using (Communicator Bob)
//-------------------------------------------------------------------------------------------------
        Display(sep1,1);
        }               // End Run method


///////////////////////////////////////////////////////////////////////////////////////////////////
}       // End public partial class CNG_SecureCommunicationExample

See Also

Tasks

How to: Build and Run the CNG Example

Concepts

Source Code Overview (CNG Example)

Cryptography Next Generation (CNG) Secure Communication Example

Other Resources

Cryptographic Services