When you receive a file that contains a digital signature, you can check whether the file was modified since it was signed, and other information.
An icon is displayed in the status bar when a file contains digital signature information. When you click the icon, you can verify the following information:
Digital signatures work on files that are compatible with AutoCAD 2000 and later drawing-file formats. If you receive a signed file and save the file, it is considered modified, and the signature is invalidated. However, you generally can still view information about it. If you receive a signed drawing-file and save the file, the signature information can be lost.
You can also view the properties of a drawing file in Windows Explorer to examine and validate a digital signature. Some operating systems display a modified icon for a drawing that has a valid digital signature attached. If the modified icon is displayed, your computer may slow down (depending on processor speed and file size), so you can turn off the display.