PDF files can be signed, but some tools can't. Open the xunjiePDF editor on the desktop, add a PDF file, set your favorite signatures in the document-signatures and abbreviations, and you can also annotate the PDF file after signing.

Win7 wants to install a driver without digital signature, just disable digital signature verification, and the specific steps are as follows:

1. Click the Start button-enter gpedit.msc in the run box and press enter;

2. Expand User Configuration-Management Template-System-Driver Installation;

3. Double-click the device-driven code signing in the right interface;

Pdf (short for portable document format) is a file format developed by AdobeSystems, which is used to exchange files in a way that is independent of applications, operating systems and hardware.