Response of shielding Ctrl+alt+del under WIN2K/NT (VC)

As you know, Ctrl+alt+del is the win2k/nt OS default system login/logoff combination key sequence, the system level is very high. In the application, it is quite difficult to block out the response to the key sequence or to get the "down" event. This paper introduces a simple and easy way to realize that after the user login succeeds, press Ctrl+alt+del to no longer eject the Windows Security dialog box.

Key words: GINA (Graphical Identification and authentication)

SAS (Secure Attention Sequence)

A Development principle

First of all, introduce Winlogon. Windows 2000/nt has three system states: No user logon status, user logon status successfully, and workstation lockout status. Winlogon is a component of the Windows 2000/NT operating system that provides interactive logon support. Winlogon has three components: executable file Winlogon.exe, dynamic library Gina DLL providing graphical interface authentication, and some network services providing dynamic library network Provider DLLs. The reference model is as follows:

Winlogon.exe handles some of the lower-level exported interface functions, and the authentication policy is designed independently in the Gina DLL. When the system starts, the Gina DLL is Winlogon.exe loaded. Microsoft provides a default Gina Dll--winnt\system32\msgina.dll that provides a standard username and password Authentication mode. The GINA DLL is replaceable, and users can design their own Gina DLL to provide other authentication mechanisms such as smart cards, retinas, fingerprints, or other.

Develop a custom Gina Dll. 18 standard function interfaces that interact with Winlogon.exe must be implemented and exported, including Wlxnegotiate, Wlxinitialize, WlxLoggedOnSAS, etc. (other function interfaces refer to MSDN). Where Wlxnegotiate is the first interface function that Winlogon.exe calls, makes the necessary version judgments, and then calls Wlxinitialize, which completes the delivery of the Winlogon.exe specific version of the function dispatch table to the GINA DLL. The author also wants to explain is the WlxLoggedOnSAS function, this function main function is, when Winlogon in the login successful state, receives the SAS event, then calls this function to carry on the SAS event recognition as well as carries on each event the corresponding processing.