JTB World’s DigSigStamp for AutoCAD allows you to specify a block that will change its display when plotted to indicate whether the drawing had a valid digital signature at the time of plotting.
The DigSigStamp AutoCAD plugin helps you identify visually when drawings have valid digital signatures. You use one of the plugin's commands to specify blocks to display when a drawing has a valid digital signature and when it does not. You then assign a particular block reference - which usually exists in the title block of your drawing - that will change its display to one of these two block definitions depending on the state of the drawing. The application even works when plotting, an operation that typically invalidates a drawing's digital signature.
The following are just examples of how the blocks can look like. The design of them is completely up to you. Digitally Signed example. This drawing has a valid digital certificate.
Invalid. This drawing does not have a valid digital certificate.
Unverified example. Digital signature verification application is not enabled.
DigSigStamp can be further customized by JTB World to fit your specific needs and requirements.
Download a trial and learn more on the DigSigStamp web page as well as on Autodesk Exchange Apps site.