Mysterious digital signatures in Windows 2000/XP

Source: Internet
Author: User
Tags versions

Do you know? The SP2 of Microsoft's digital signature is the official version (right-click to open the file Properties window to see the digital signature information shown in Figure 1).

Figure 1

The File Protection feature of Windows

In previous Windows 2000 versions of Windows, software that was installed outside the operating system might overwrite some of the shared system files, such as dynamic-link libraries (*.dll files), executables (*.exe), which could cause the program to run unstable, system failure, This is mainly due to the so-called DLL traps.

To address this problem completely, Microsoft introduced the Windows File Protection mechanism in Windows 2000 and Windows XP to prevent replacement of protected system files, including *.sys, *.dll, *.ocx, *.ttf, *.fon, *. EXE-type files, Windows File Protection runs automatically in the background, and you can protect all files installed by Windows Installer.

If Windows File Protection detects the intention of another program to replace or move a protected system file, what is it based on? In fact, Windows File Protection is by detecting the digital signature of a file to determine whether the new version of the file is the correct version of Microsoft, or if the file version is incorrect, Windows File Protection automatically calls the Dllcache folder or a backup file stored in Windows to replace the file, prompting the user to enter that location or insert the installation disc if Windows File Protection cannot locate the appropriate file.

Ii. understanding of digital signatures

A digital signature is allowed to be authenticated, and if a file does not have a valid digital signature, it will not be possible to ensure that the file actually comes from the source it declares, or that it has not been tampered with since it was released (which could be tampered with by a virus). At this point, it is safer to open the file safely unless you determine the creator of the file and know its contents, otherwise it is not recommended to open it easily. The logo for Microsoft Windows XP design (designed for Microsoft Windows XP) is generally present on the packaging of hardware or software that has been digitally signed by Microsoft.

When new software is installed on your computer, system files and device driver files are sometimes overwritten by unsigned or incompatible versions, causing system instability. System files and device driver files that are provided with Windows XP have a Microsoft digital signature, indicating that these files are original unchanged system files, or that they have been agreed to be used by Microsoft for Windows. The File Signature Verification tool is available in Windows 2000/XP (see Figure 2), and Windows 9x provides the System File Checker, which allows us to check the digital signature status of system files.

Figure 2

Windows File Protection is always enabled by default, and Windows digital signature files are allowed to replace existing files. Currently, signature files are distributed in the following ways: Windows Service Pack, patch distribution, operating system upgrades, Windows Update, Windows Device Manager/category installer.

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