Doesn’t DRM piss you off? Not being able to share the music you bought with your kids, parents or wife? Sure you may avoid DRM-ed content whenever you can, but sometimes you just can’t, simply because what you want isn’t available in a DRM-free flavour. How about not being able to make a backup copy of your legally-purchased music CD? Wanting your purchased music to be digestible to a portable jukebox of choice anyone? Be it mp3 player or whatever else…

Alright, I guess we agree it is annoying, especially in the way it is widely forced on us by major players of the industry. But, besides some moves in a good direction some time ago, Palm has a very nice solution for quite some time that they use to protect books they sell. It is a DRM, but lacks almost all the burdens of the rest of the breed. It works in a fairly simple way — when a customer buys a book, a unique file is generated for them, and them only, that has beforehand been wrapped in some crypto using buyer’s name and their credit card number, provided in order to purchase the book, as keying material. In other words, in order to read the obtained copy of the book one needs to know the purchaser’s name and their credit card number.

Neat, isn’t it? The benefits seem quite obvious — when the protected content is tied to user’s vital confidential information, by caring for the information to remain confidential they also protect the purchased content from getting out of the trusted hands. Literally, the access to the content is limited only to people to whom the customer feels comfortable entrusting their credit card number. It effectively limits co-readers of the copy to family and closest friends. Very fair by me.

When will it fail? Obviously, when the credit card expires, the customer doesn’t care anymore, so the protection period is up. But, is it really that bad? In average cases, when the purchase is made some years before the credit card expires, well… after those couple of years it’s not hot stuff anymore… so, well… I guess merchants can live with such a book leaking after those years.

The only thing a user could find themself concerned about is “exactly how safe are my billing details once used for the content locking?” And well… the answer is “hell knows”. In general, it’s perfectly possible to make the keying material (billing details in this case) so hard to be pulled out of the crypted content that with contemporary knowledge and computational power it is not even worth starting… But, how has this been done in case of Palm protected e-books remains a mystery. Nevertheless, the general idea is undoubtedly clever.