I'm a AutoCAD teacher for 30+ years now. I do have 1000+ tutorial-pages which are outputed in *.pdf from within AutoCAD Of course the source of this *.pdf is vector-based, hence those *.pdf could be imported back in AutoCAD, recuperating a lot of geometry and text. This is my problem, I do not want that anyone can retrieve my work over all these years. My questions: - Could PDF-A be a solution (or another flavor of PDF?) - Is there any embedded Website PDF-viewer which does not allow to download the *.pdf? or perhaps a hosting site which is able to achieve this? Thank you.
Those solutions won't really work. To view a PDF file it has to be downloaded first, so that won't solve your problem.
Basically, there isn't any real solution, unless you're willing to invest a lot of money in DRM technology to protect your files. Alternatively, why not export them as bitmap images, and create new PDF files from those? That way they won't be vector-based any longer and importing them in AutoCAD (or any other vector-based program, like Illustrator) won't yield a file that you can work on (at least not with a lot of effort)?