How should I secure my ebooks?
apage43: If you use -any- sort of DRM, it will be extremely restrictive to the end user. Personally, I think really what is needed is for it to be convenient for the end user. This is what keeps me buying music from Amazon MP3. I don't even need any software other than a browser if I'm buying a single song. There's nothing to stop me from sharing my files with a few friends but Amazon MP3 probably makes up for whatever sales that would be lost this way because I like the service so much I recommend it to people all the time. Just give the user a raw, non-drm PDF file. If you really need to do -something-, dynamically insert a unique user ID on the last page of the book, just on the page, no steganography, write "Purchased by user #12345." PDF is pretty much a read-only format, so this wouldn't be easy to remove.This probably won't keep people from casually sharing the book with their friends but will probably effectively put them off of sharing it publicly on the internet or p2p.