Quote:
Originally Posted by GJN
That makes a great deal of sense. It seems to me, though, that if I delete a book after lending it and then restore it from a backup made before lending it, I might be able to read or relend the book. They may keep a list of lent books, though, in a separate database on the reader where they'd keep track of ALL your books.
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Now that's a scenario I hadn't thought of-and it shows the impracticality of copy-protection schemes. It doesn't seem likely, to me, that they'd bother keeping track of books you delete, but they might store the 'decryption' key in a separate database so, when you delete the book you'd also delete the key. I hope they don't do that unless they let you back up the database, too.
When I speak of keeping a 'backup' of ebooks I generally mean just copying the file to an off-device location. In this scenario, that wouldn't work, but if they provide a 'backup' function that will copy the file to an off-device location & also copy the key, probably to an off-device database, then it might be acceptable. Except I think it would still allow the scenario you set up.
So basically, what I think you've proven is that the only way copy protection can be 'perfect' is to so restrict it that it makes the product virtually unusable. (I.e, the user needs to remove it to make the product usable. I suppose that 'perfect' copy protection couldn't be removed, but that's a different matter. Here, I'm talking about copy protection that allows both lending & backups without maintaining a database of every book you've ever loaded onto the device.)
Hmm, thinking about maintaining a database of every book you've ever loaded, I can't see that ever being accepted by consumers. Right now devices have a limit to the number of books they can simultaneously hold-but if they implemented that database then devices would have a 'lifetime' limit to the number of books they can hold, thus making devices even more disposable than they are now.
(Assuming consumers would put up with it, I'm sure that manufacturers would be pleased to produce a book that allows you to read say 500 books-then you need to buy a new device.)