Hasp4 API hooking or dll replacement

This is my first post, so be gentle

I am interested in Hasp4 emulation, but it looks to me that for some reason every one tries to use the complex approach.

Trying to emulate a dongle by creating a device driver.

I have noticed the HASPMS32.DLL which has only one exported function:
void PASCAL hasp(int iMsg, int a, int b, int c, int d, int * e, int * f, int * g, int *h)

Why not just replace this dll or do some fancy API hooking, to let the applications call our void hasp (...) method.

Using a newly created dll, and adding one method:

#define   IS_HASP            1
#define   GET_HASP_CODE      2
#define   READ_MEMO          3
#define   WRITE_MEMO         4
#define   GET_HASP_STATUS    5 
#define   GET_HASP_ID        6 
#define   READ_MEMO_BLOCK   50
#define   WRITE_MEMO_BLOCK  51

void PASCAL hasp(int iMsg, int a, int b, int c, int d, int * e, int * f, int * g, int *h)
{
	AFX_MANAGE_STATE(AfxGetStaticModuleState());
	CString str;

	switch ( iMsg )
	{
	case IS_HASP:
		//str.Format( _T("IS_HASP\r\n"));
		if ( e ) 
			*e = 1;
		if ( g ) 
			*g = 0;
		break;
	case GET_HASP_CODE:
		str.Format( _T("GET_HASP_CODE Seed:%d LPT:%d Pass1:%d Pass2:%d\r\n"),a,b,c,d);
		break;
	case READ_MEMO:
		str.Format( _T("READ_MEMO\r\n"));
		break;
	case WRITE_MEMO:
		str.Format( _T("WRITE_MEMO\r\n"));
		break;
	case GET_HASP_STATUS:
		str.Format( _T("GET_HASP_STATUS LPT:%d Pass1:%d Pass2:%d\r\n"),b,c,d);
		break;
	case GET_HASP_ID:
		str.Format( _T("GET_HASP_ID LPT:%d Pass1:%d Pass2:%d\r\n"),b,c,d);
		if ( g ) 
			*g = 0;
		break;
	case READ_MEMO_BLOCK:
		str.Format( _T("READ_MEMO_BLOCK\r\n"));
		break;
	case WRITE_MEMO_BLOCK:
		str.Format( _T("WRITE_MEMO_BLOCK\r\n"));
		break;
	}
	if ( str .IsEmpty() == FALSE )
		AfxMessageBox( str );

}

It will popup a message box showing the call, and the passwords
Some tools just check the IsHasp and that's it.

When a real dongle is near, just modify code too call actual hasp method and remember return values. Almost every app has fixed seeds values, to check known return value with.

Using this simple approach I was able to run envelopped HASP4 applications.


Well... what do you think of this ?