I would like to sell downloads of a book I have written. However, nothing stops people from taking PDF files and any password and forwarding to them other people.

Is is possible to make downloads accessible only on particular computers? Is there a way I can restrict access to only their computer, so they can't then forward my entire book download to everyone they know. I know companies who sell computer programmes have created it so that people have to registar to have access and the programme is only accessible on two computers.Is there some way I can apply a similiar thing to downloading a document (i.e.my book)? Any suggestions?


Many thanks, Rachel