When you connect a new device to your PC, Windows tries to find and install a driver for the device. Occasionally, you might see a notification that a driver is unsigned, has been changed since it was signed, or can't be installed by Windows. We recommend that you don't install unsigned or changed drivers.
A digitally signed driver includes a digital signature, which is an electronic security mark that can indicate the publisher of software, as well as whether someone has tampered with it since it was signed. If a driver has been signed by a publisher that has verified its identity with a certification authority, you can be confident that the driver comes from that publisher and hasn't been changed.
Windows will notify you if a driver is unsigned, was signed by a publisher that hasn't verified its identity with a certification authority, or has been changed since it was signed and released to the public. If you see any of the following notifications when you're installing a driver, you should go to your device manufacturer's website to get a digitally signed driver for your device.
The driver doesn't have a digital signature or has been signed with a digital signature that wasn't verified by a certification authority. You should only install this driver if you got it from the manufacturer's disc or from your system administrator.
The driver hasn't been digitally signed by a verified publisher. The driver might have been changed to include malware that could harm your PC or steal information. In rare cases, legitimate publishers do change drivers after they've been digitally signed, but you should only install an unsigned driver if you got it from a device manufacturer's disc.
Unfortunately, there's no trustworthy source of information that indicates who has published an unsigned driver. Anyone can change the contents of an unsigned driver, and there's no way to know why it was changed. Most manufacturers now digitally sign the drivers they create before releasing them to the public.
A driver that lacks a valid digital signature, or has a signature that was changed after it was signed, can't be installed on 64-bit versions of Windows. You'll only see this notification if you have a 64-bit version of Windows and try to install such a driver on it.