The Technology of Rights: Digital Rights Management

By Karen Coyle

Based on a talk originally given at the Library of Congress, November 19, 2003


You have probably heard the expressions "thin copyright" and "thick copyright referring to different philosophies about copyright law." Very briefly, thin copyright usually refers to a minimalist approach to copyright, giving works only as much protection as is needed to encourage creativity but with a goal of making works readily available to the public. Thick copyright is a more maximalist approach, and crudely put the goal of thick copyright is generally to maximize profits. We appear to be moving toward thick copyright, not only in this county but around the world in general. This movement is being spearheaded, as you might expect, by companies whose main product is in the form of intellectual property, such as books, movies and music.

But there is yet another trend relating to the protection of intellectual property and that is the creation of technological controls to protect digital works. This is referred to as Digital Rights Management, or DRM. DRM is not a single technology and it is not even a single philosophy. It refers to a broad range of technologies and standards, many of which are still in the planning and development stage. DRM is not thin copyright, and it isn't even thick copyright; DRM is potentially a nearly absolute protection of works.

"With the development of trusted system technology and usage rights languages with which to encode the rights associated with copyrighted material, authors and publishers can have more, not less, control over their work."
Mark Stefik, Shifting the Possible: How Trusted Systems and Digital Property Rights Challenge Us to Rethink Digital Publishing
Berkeley Technology Law Journal, v. 12, n. 1, Spring, 1997

In the remainder of this article we will look at how DRM protects works today and where this technology may be headed in the future.

Why Do We Need DRM?

What's the motivation behind digital rights management? Let me give you a simple illustration. Say I have a book, a hard copy book, that I have borrowed from the library. Maybe I would like to have a copy of my own. What prevents me from going down the street to a copy center and making myself a copy of the book? Well, it's copyright law that prevents me from doing that, isn't it?

In fact, that's not true at all. Copyright law does not prevent me from making the copy. It may make me feel a bit guilty about making the copy, or I might fear getting caught, but it doesn't prevent me from making the copy. Yet I am unlikely to copy the book. Why is that? Because I don't want to spend an hour and a half at a copy center opening the pages and punching the copy button. Because in the end the copy will cost me as much or more than buying a copy of the book in paperback. And because what I will end up with is a poor copy on bad paper in an 8.5x11 format, unbound. In the end, making a copy of a hard copy books is uneconomical, in terms of time and money, and the result is pretty undesirable.

Now let's say that I have the very same book in a digital format. If I want to make a copy, I can make that copy almost instantly. It will cost me nothing. And the end result will be a perfect copy of the original. Not only that, I can make one hundred or a thousand copies almost as easily as I can make one. I can email the file to everyone in my address book, or I can place the file on a peer-to-peer network and let anyone on the Internet have access to it. With the digital file, the economics are slanted very much toward making copies.

Note that the digital file is protected by the very same copyright law that the hard copy is, the one that doesn't really prevent us from making copies. What we have here is the Napster effect, which is based on the ease of copying. And because law doesn't seem to have worked as a preventive measure, there is some justification that only a technology-based protection will ever work to protect digital works.

Why Encryption Isn't Enough

Whenever you talk about protecting digital files, encryption is part of the answer. But the protection that encryption offers has its own limitations. To begin with, encryption does not prevent you from copying a file. Copying a file is just a matter of moving a series of ones and zeroes from one digital device to another, and you can copy an encrypted file just as easily as you can copy an unencrypted one. You can also email it, or place it on a peer-to-peer network. The protection that encryption provides has nothing to do with copying; instead, encryption prevents access to the content of a file. And this is a key point to understand about both encryption and about digital rights management: that the controls are on access and on use rather than copying. You can copy an encrypted file dozens of times, but none of those copies have any value if you cannot access the content. And there's very little value in sending such a file to anyone else, unless they have the key.

So how does encryption actually help protect files? Let's step through a few scenarios that will illustrate the way that encryption can be used in a DRM system. I'll pretend that I have written an ebook and Jane wants to buy it.

In this first scenario, I encrypt the ebook and send it to Jane, with an email that tells her the key to use to open the file. Have I protected the book? No, not at all. Jane now has the book and she knows the key. She can send the book to all of her friends and tell them the key, so everyone can have a usable copy. Encryption only works when the person holding the key is the one who wants to protect the digital file. Giving the key to anyone else negates the purpose of the encryption. You could argue that I could decide to trust Jane to keep the key to herself, but in general we can assume that Napster, Kazaa, and other trading networks have pretty much eliminated "trust me" as an option that owners of intellectual property will go for.

How can I get the key to Jane without actually giving her the key? One solution is that I can give the key to Jane's computer, not to Jane. In this scenario, Jane buys my ebook and I allow her to download it to her computer. At the same time, she downloads a small file that is also encrypted but that contains the key that opens the ebook. The ebook software that she is using can unencrypt this key file, often called a "voucher," and can then use the key to open the ebook. Jane never sees the key. And she may be unaware that there is a key file because it may be sent to her machine as a hidden file, or it may be otherwise disguised with an odd name or place on the hard drive.

Does this protect the ebook? No, because if Jane is clever, she can figure out that by making copies of both files and sending them to a friend, that friend can also access the file and read the ebook because she has both files on her computer. Anyone possessing the two files can read the ebook, whether or not they paid for it.

So now our question is, how can we give the key to Jane's computer in a way that Jane can't send it on to others? We do that by tying the key to the identity of Jane's hardware. In this scenario, Jane pays for the ebook. In the exchange that takes place as Jane negotiates her payment between her computer and mine, a program returns to my site some piece of identifying information about Jane's computer. This may be a identification number of her CPU, a serial number from her hard drive or her BIOS. The main thing is that is is something that uniquely identifies Jane's computer and it is not something that she can readily change. Now when Jane opens the file on her machine, the voucher file contains a record of that unique hardware identification, and the program that opens the file will not work if the hardware of the current machine doesn't match the hardware ID in the voucher. If the digital file and the voucher are moved to another machine, the program will not open the file. Instead, the user may see an error message like this one:

Invalid CPU Identifier

This technique of tying a digital file to a particular piece of hardware is a common DRM solution today. It has obvious problems in a world where the average life of hardware is two to three years, but at the moment it is the best method we have to control access to a digital file. To create a better solution, one that would connect the digital file to a person rather than to a machine. This would allow a person to move files from one computer to another in the way that you pack up your books and move them from one house to another, requires a more sophisticated technology called "trusted systems." We'll discuss the work being done around trusted systems further on in this article, but suffice it to say at this point that trusted systems may be the next level of development in digital rights management.

Next: Usage Rights

©Karen Coyle, 2003
Creative Commons License
This work is licensed under a Creative Commons License.