Thread: Generate Ctrl-Alt-Del programmatically

Hello guys,

I want to generate Ctrl-Alt-Del key sequence programmatically.

I have searched a lot on net but don't get any solution.

I have tried to fill keyboard buffer with 'keybd_event()' function. But it is also not working. It seems that it fills application's key buffer.

Anyway......can anybody help me to solve this problem ?

Thanking You,

I read somewhere that CTRL ALT DEL actually generates a hardware interrupt in the keyboard.

WM_KEYDOWN and WM_KEYDOWN are notification messages, so sending messages with them will not work. Basically, a notification message is something that tells you something happened... it doesn't make it happen. Take a look at this thread for a good example of the difference between sending a message that does something or sending a notification (something you should never do, since all it does is fool your program into believing something happened that did not really happen).

Ya, you are right,

I have tried most of the function and trick to fill key buffer such as : SendMessage(), PostMessage(), BroadcastSystemMessage(), WM_KEYDOWM, WH_HOTKEY, keybd_event() and so on. But they all are not working...

Still I don't get solution...

MSDN states that "The SendInput function inserts the events ... serially into the keyboard or mouse input stream". By serially, doesn't that mean not at the same time? That means it wouldn't be able to simulate CTRL-ALT-DELETE all at the same time.

I haven't tried implementing the function, but I just found that interesting.

Okay, I tried using SendInput() and it didn't work. Here's my code:

Code:

int main(void)
{
	INPUT inp;
	KEYBDINPUT kbi;
	int a=0;

	kbi.wScan=0;
	kbi.dwFlags=0;
	kbi.time=0;
	kbi.dwExtraInfo=0;
	inp.type=INPUT_KEYBOARD;

	kbi.wVk=VK_CONTROL;
	inp.ki=kbi;
	a+=SendInput(1,&inp,sizeof(INPUT));

	kbi.wVk=VK_MENU;
	inp.ki=kbi;
	a+=SendInput(1,&inp,sizeof(INPUT));

	kbi.wVk=VK_DELETE;
	inp.ki=kbi;
	a+=SendInput(1,&inp,sizeof(INPUT));

	cout << a << endl;

	a=0;

	kbi.dwFlags=KEYEVENTF_KEYUP;

	kbi.wVk=VK_CONTROL;
	inp.ki=kbi;
	a+=SendInput(1,&inp,sizeof(INPUT));

	kbi.wVk=VK_MENU;
	inp.ki=kbi;
	a+=SendInput(1,&inp,sizeof(INPUT));

	kbi.wVk=VK_DELETE;
	inp.ki=kbi;
	a+=SendInput(1,&inp,sizeof(INPUT));

	cout << a << endl;

	getch();
	return 0;
}

So basically, I send CTRL-ALT-DELETE keydowns then CTRL-ALT-DELETE keyups. Nothing happens. The output tells me that all 6 events have been successfully inserted into the input stream. Have I done something wrong, or is this just not the way to do it?

Originally posted by XSquared
I read somewhere that CTRL ALT DEL actually generates a hardware interrupt in the keyboard.

If this is true, then you will have to issue this hardware interrupt yourself to emulate it. This is easy to do in good 'ol MS-DOS, but Windows is purposely made so that this is not so easy to do...

Ctrl-Alt-Del is Windows's "Secure Attention Sequence". It is designed to be non "hookable" etc., the reason being that when one presses Ctrl-Alt-Del one is sure one is talking to the OS rather than any kind of trojan. This is Orange Book stuff.

It seems reasonable to me that this being the case, generating this sequence would also be restricted/pointless. I cannot find a specific prohibition, but I have tried to generate it, and used some really rather deep hacks. None have worked - I have given up trying.

I have never had a legit reason for doing so, it was an intellectual challenge which, it would seem, I was not up too!

The messages your application receives are the ones that Windows has chosen to send you. If you press Ctrl-Alt-Del, there is no reason why Windows should send you anything, apart possibly, from a loss of primary focus. At that point, you are now communicating with Windows, not the application which had focus before the sequence was pressed.

Sending Ctrl-Alt-Del to a co-operating task on another machine is not the same as pressing it locally. When you tell PCAnyWhere to send Ctrl-Alt-Del to a remote client, it is sending a message saying it would like to press Ctrl-Alt-Del to a co-operating task on the local machine. This task can then instigate a reboot or whatever. Different case.