wow, isn't that a good idea!!! Startup idea for anyone who wants it.
And that's without even getting into the slippery slope aspects of DRM technology.
it is very possible to implement encryption and signing without having the user go through key generation etc. make it all transparent and give them a lock to click on if they want to make the message and attachments secure. PGP already has a similar product, and hushmail is pretty easy to use.
The image needs to be displayed on the receiving end. From that point the cat is out the bag, no matter how many locks you put on the bag.
its pretty standard, and working with e-commerce for a while now.
In what area of "e-commerce" is that standard and working? I don't know of any but I know at least one where DRM was tried and failed miserably (music distribution).
Moreover I can only repeat that DRM is technically infeasible for images because the images need to be displayed on the clients screen. When your eyes can see it then the lens of your digicam can also see it. Get it?