Alice.cs Source Code (CNG Example)

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

using System;                           // Required for the IDisposable interface
using System.Text;                      // Required for the Encoding class
using System.Security.Cryptography;     // Required for the CNG APIs


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

static void Main()
    {
    if (!Autoloader())                  // Load Bob and Mallory
        return;                         // An error was encountered during load.

    string s = "";
    InitConsole("Alice Green", 5, 5);
    while (true)
        {
        SplashScreen();                 // Set and display titles
        s = InitializeOptions();        // Get session options
        AppControl("send", s);          // Synchronize Bob and Mallory
        if ("exit" == s)                // Quit if user entered "x"
            break; 
        Run();                          // Run the desired session
        }
    }                                   // End Main


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

static void Run()
    {
    string NewChannelName = "AliceAndBobChannel";   
    SendChannelName(NewChannelName);    // Bad corporate security policy 

    Display("Hi, I'm Alice Green. My sales associate is Bob White.\n" +
            "I need to send him a customer order right now!\n\n");

    using (Communicator Alice = new Communicator("server", NewChannelName))
        {
        string s;

        CngKeyCreationParameters keyCreateParms = new CngKeyCreationParameters();
        keyCreateParms.ExportPolicy = CngExportPolicies.AllowPlaintextExport;

        if (3 <= Version)              // Send public digital signature key
            {
            using (CngKey DSKey = CngKey.Create(CngAlgorithm.ECDsaP521, null, keyCreateParms))
                {
                byte[] dsKeyBlob = DSKey.Export(CngKeyBlobFormat.Pkcs8PrivateBlob);
                Alice.StoreDSKey(dsKeyBlob);
                s = Encoding.ASCII.GetString(dsKeyBlob);
                Display("\nFirst, I will send Bob a digital signature key "
                        +"over a public channel.\n" +
                        (fVerbose ? "Here it is:\n\n" + s + "\n\n" : ""));
                Alice.ChMgr.SendMessage(dsKeyBlob);
                }
            }

        if (4 <= Version)              // Send private digital signature key
            {
            using (CngKey DSKey = CngKey.Create(CngAlgorithm.ECDsaP521, null, keyCreateParms))
            using(ChannelManager ChMgr2 = new ChannelManager("server", "PrivateChannel"))
                {
                byte[] dsKeyBlob = DSKey.Export(CngKeyBlobFormat.Pkcs8PrivateBlob);
                Alice.StoreDSKey(dsKeyBlob);
                s = Encoding.ASCII.GetString(dsKeyBlob);
                Display("\nNow I will send Bob a secret digital signature key " +
                        "over a private channel.\n" + 
                        (fVerbose ? "Here it is:\n\n" + s + "\n\n" : ""));
                ChMgr2.SendMessage(dsKeyBlob);
                }
            }

        if (2 <= Version)              // Send and receive public cryptographic keys
            {
            Display(sep2, 1);
            Display("Now we will exchange our public cryptographic\n" +
                    "keys through a public channel\n" +
                    "First, I'll send Bob my key.\n\nSending...\n");
            Alice.Send_or_Receive_PublicCryptoKey("send", MyColor);


            Display(sep2, 1);
            Display("Now Bob will publically send me his "  +
                    "public crypto key:\n\nListening...\n");
            if (!Alice.Send_or_Receive_PublicCryptoKey("receive", OtherColor))
                {
                Display("", 6);
                return;
                }
            }

    //-----------------------------------------------------------------------------------
    // 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", 4);
            Display(sep1, 1);
            }

        Alice.SendMessage("Hi Bob. I have a new customer contact.",true);
        Alice.ReceiveMessage();
        Alice.SendMessage("Coho Winery, 111 AnyStreet, Chicago",true);
        Alice.ReceiveMessage();

        if (Version <= 2)
            Display(sep1, 1);

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

    //-----------------------------------------------------------------------------------
        Display("Would you like to talk to Bob?\n" +
                "If so, type a message, and press Enter.\n" +
               "Otherwise, just press Enter.\n\n", 1);
        Display(sep + sep1,1);
        s = " ";


        while (true)
            {
            s = ReadALine(true); 
            if (!Alice.SendMessage(s,false))    // If Bob entered CTRL-C, or SYS_CLOSE
                break;
            if ("" == s)                        // If user entered ""
                break;
            s = Alice.ReceiveMessage();         // Read a message
            if ("" == s)
                break;
            }

    //-----------------------------------------------------------------------------------
        }   // End using ChannelManager, End using Communicator
    }       // End Run

}       // End Alice.cs: 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