You can use a digital signature to sign a drawing or group of drawings from within AutoCAD or by using a batch tool found in the Autodesk program group. It is important to remember that a digital signature is an attached, encrypted certificate. Not a visual representation of a handwritten signature. A digital signature provides security for both the person sending and receiving the signed file by tracking if the drawing has been changed or not since it was last signed.
Let’s start by looking at the process of using a digital signature in AutoCAD. First you must purchase a Digital ID. These can be purchased from Verisign or a number of other vendors. Then select Start > Programs > Autodesk > Your Version of AutoCAD > Attach Digital Signatures. In the Attach Digital Signatures dialog box you select the drawings that you want to sign, a time stamp, and add any comments desired. Then Select the <<Sign Files>> button. You now have files with your digital signature attached.
A Digital Signature tab is added to the properties of the file along with a read-only attribute. When you open the drawing the same information about the digital signature is also displayed.
The digital signature does not prevent changes from being made to a drawing. However, if the drawing is saved the digital signature will be invalidated. This allows you to know if anyone has changed the drawing that you sent them. It also allows you to be sure that the drawing you received is from the person you think that it is.
This all being said, many of you may be faced with legal requirements that have not caught up with the technology of digital signatures, even though the digital signature is much more difficult to forge than a handwritten one, if not impossible. In that case they may still have some value to you, but they will not replace a handwritten signature. It is also important to remember that you can use a digital signature to sign almost any kind of document from a CAD drawing to a Word document or even an email. My prediction would be that the technology will continue to improve and that the law will catch up with it. Both of these things will make digital signatures more and more common over the next several years. It will also become more important as submittals include more electronic documents, which is another topic altogether.
Other resources:
Autodesk:
http://www3.autodesk.com/adsk/files/877487_Extnsns_WP_introdigsig.pdf
Verisign:
https://digitalid.verisign.com/client/help/id_intro.htm#whatis_signature
American Bar Association:
http://www.abanet.org/scitech/ec/isc/dsg-tutorial.html
