How could I transform some keypresses into other keypresses?

I have a great idea about cheating on exams. My school uses very old IDE's ( think Turbo Pascal, Turbo C++ , and other 80's ones ), and the thing I开发者_Go百科'd like to do is this :

• start my program in the background

• intercept the keypresses, and instead of sending them directly to the screen, I'd like to read a character from a pre-configured text-file, and send that as the pressed key. This way, no matter what you'll write, the text from that file will get written on the screen.

I found Stephen Toub's article about logging keys, and I think it will serve as a good start on building this "tool". Is there a better alternative to intercepting all the keys pressed in the system than SetWindowsHookEx? Will the code be flagged by the antivirus as a suspicious program? If so, is there anything else I can use to accomplish this without being flagged by the antivirus? Will administrator priviledges be required ?

I know some of you guys will say that If I'd put as much interest in learning as I do in avoiding learning, I'd do great, but I'd like to try this out.

EDIT: I've added a bounty, I'm interested in some techniques for capturing keystrokes ( I'm not interested in low-level hooking or advanced stuff - basic ones are fine ), mainly method names and some links to documentation. I'd also like to know if they would appear as malware to an antivirus.

GOD! I've just found the perfect class for this the other day.. took me a while to find the original source:

http://www.codeproject.com/KB/cs/globalhook.aspx

I used this (and SendKeys) alone exactly for what you need, you'll need to use Handle=true to block the original key message.

SendKeys is a bit ugly... you can look for a replacement if you'd like.. but SendKeys will work for you.

With SendKeys it's something like:

    private void HookManager_KeyDown(object sender, KeyEventArgs e)
    {
        if (e.KeyCode == Keys.D){
            e.Handled = true;
            SendKeys.Send("F");
        }
    }

I actually also use this method to determined what prccess' window is in focus, so the app will do nothing if you are on another application:

    /// <summary>
    /// The GetForegroundWindow function returns a handle to the foreground window.
    /// </summary>
    [DllImport("user32.dll")]
    static extern IntPtr GetForegroundWindow();

    static bool IsProcessFocused(string processname)
    {
        if (processname == null || processname.Length == 0)
        {
            throw new ArgumentNullException("processname");
        }

        Process[] runninProcesses = Process.GetProcessesByName(processname);
        IntPtr activeWindowHandle = GetForegroundWindow();

        foreach (Process process in runninProcesses)
        {
            if (process.MainWindowHandle.Equals(activeWindowHandle))
            {
                return true;
            }
        }

        // Process was not found or didn't had the focus.
        return false;
    }

SetWindowsHookEx is the best option. I've been told that some antivirus programs will flag it, but I created a little app once using it and scanned it with AVG which returned no virus alerts.

Not that I'm saying cheating is good, but we understand your plea. I dont' think it's possible without getting into API hooks, since .Net wraps WIN32 API's I don't think they have wrapped methods for what you want.

For completeness, let's just add some details:

Unfortunately you have to get into the WIN32 API's: http://msdn.microsoft.com/en-us/library/ms645530(VS.85).aspx

The WM_SYSKEYDOWN notification can be used to get the key strokes, but it takes the handle of the window to watch, so it would involve the *GetWindow** API's to get the handle of the window you want to monitor.

Try the SendInput or keybd_event [http://msdn.microsoft.com/en-us/library/ms646304(VS.85).aspx] functions to simulate keystrokes.

Google "WIN API Viewer" for a utility to easily search for and view said API's, there is a version for .Net code too.

It's one of those things that will take a lot of trial and error, and I wish I had a more definitive answer for you.

As far as I can say, the most reliable way to keylog is to set up a system wide interrupt (I think INT17h?), but that's pretty low level, considering that your post is tagged C#. Go search for a relevant tool... you'll find many...