AutoDWG DWGLock 2.91 Free download

A powerful and fast dwg tools, Protecting drawing file, Keep others from modifying/copying your design. DWGLock is a stand-alone application, no AutoCAD required; Supports AutoCAD R2.9 thru 2011 drawings.
Features:
Powerful encryption capabilities, secure Maximize security for the entities in the drawing, they can not copy nor change it.Say No to any arbitrary use of your designs;
Recipients can open up to view protected drawing without any inconvenience, they can even add lines, markup.Preserve or discard their comments, it's all up to you!
The drawing owner can lock or unlock the source drawing with a password;
Batch encrypt/un-encrypt many files or folders just in one go.