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RFID on DVDs

May 12, 2005 by

A group at UCLA is studying how to deter DVD copying by putting RFID chips on DVDs, according to a story in RFID Journal by Mary Catherine O’Connor. (Noted by Rik Lambers at CoCo.) The article doesn’t say much about what they are planning. Reading between the lines, it looks like the group hasn’t reached the really interesting technical challenges yet.

Putting RFID on DVDs could be a terrible idea if done the wrong way. But if done correctly, it just might make sense.

One bad approach is to store part of the decryption key (needed to decrypt the data on the DVD) on an RFID chip that is attached to the DVD. The DVD player would read this partial key from the RFID and use it, along with the DVD player’s secret key, to decrypt the content. Doing this doesn’t make the content much harder to copy. And it creates several new problems: the new DVDs wouldn’t play in existing players, and the RFID might expose customers to tracking if they carry RFID-DVDs around with them.

A better approach is to use RFID to put a unique “bonus code” on each individual DVD disc. Then you can provide online “bonus features” to users who present a valid bonus code that isn’t being used elsewhere at the same time. If the bonus features are good enough, users will value getting a bonus code and so will be willing to pay more for genuine discs. And the discs will work in existing DVD players, albeit without the bonus features.

Of course, bonus codes can be copied, just like content. But if bonus codes are used to get live access to a website, and that website checks to avoid duplicate use of bonus codes, then widely copied bonus codes will be less useful, and users will have an incentive to protect their bonus codes from copying.

You don’t need RFID to bundle bonus codes with DVDs. Instead, you could put the bonus code onto the DVD with the content, but this may raise manufacturing costs, by requiring each DVD to contain some unique data, rather than being stamped out in large, identical batches. Or you could print the bonus code onto a sticker and attach the sticker to the DVD case or to the DVD itself. That’s low-tech and effective, but it requires the user to manually enter the bonus code, which is a hassle. RFID allows the DVD player to read the bonus code directly.

If you wanted, you could put the bonus code on both a sticker and an RFID. The DVD player would read the RFID if it could; otherwise the user could enter information from the sticker. Users who worried about privacy could tear off the RFID and just use the sticker. Computer-based DVD players could remember the bonus codes, so the user didn’t need the RFID or sticker anymore.

There are still privacy problems, but these could be addressed if you had a more advanced RFID chip that could execute the right cryptographic protocol. Then the chip could authenticate itself to the bonus features website, in a way that didn’t allow any individual RFID chip to be tracked from moment to moment.

This may be overkill. It’s a lot of technology to get you a relatively small benefit, compared to alternatives like using stickers, or using a disc manufacturing process that can put a small amount of unique data on each disc. But the idea of using RFID with DVDs isn’t totally crazy.

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Newsweek Fails AP Math

May 11, 2005 by

Newsweek just released its list of the top 100 U.S. high schools. Like the more famous U.S. News college rankings, Newsweek relies on a numerical formula. Here is Newsweek’s formula:

Public schools are ranked according to a ratio devised by Jay Mathews: the number of Advanced Placement and/or International Baccalaureate tests taken by all students at a school in 2004 divided by the number of graduating seniors.

Both parts of this ratio are suspect. In the numerator, they count the number of students who show up for AP/IB tests, not the number who get an acceptable score. Schools that require their students to take AP/IB tests will do well on this factor, regardless of how poorly they educate their students. In the denominator is the number of students who graduate. That’s right – every student who graduates lowers the school’s rating.

To see the problems with Newsweek’s formula, let’s consider a hypothetical school, Monkey High, where all of the students are monkeys. As principal of Monkey High, I require my students to take at least one AP test. (Attendance is enforced by zookeepers.) The monkeys do terribly on the test, but Newsweek gives them credit for showing up anyway. My monkey students don’t learn enough to earn a high school diploma – not to mention their behavioral problems – so I flunk them all out. Monkey High gets an infinite score on the Newsweek formula: many AP tests taken, divided by zero graduates. It’s the best high school in the universe!

Why does Newsweek use this formula? There are two reasons, I think. First, they seem to conflate AP courses with AP exams. It is indeed good if more students take genuine AP courses, which teach the most challenging material. But there’s no point in having students take the AP exams if they’re not prepared. Some schools require their students to take AP exams, whether they’re prepared or not. The Newsweek formula rewards those schools. Here’s Jay Mathews, in Newsweek’s online FAQ:

If I thought that those districts who pay for the test and require that students take it were somehow cheating, and giving themselves an unfair advantage that made their programs look stronger than they were, I would add that asterisk or discount them in some way. But I think the opposite is true. Districts who spend money to increase the likelihood that their students take AP or IB tests are adding value to the education of their students. Taking the test is good. It gives students a necessary taste of college trauma. It is bad that many students in AP courses avoid taking the tests just because they prefer to spend May of their senior year sunning themselves on the beach or buying their prom garb. If paying your testing fee persuades you, indeed forces you, to take the test, that is good, just as it is good if a school spends money to hire more AP teachers or makes it difficult for students to drop out of AP without a good reason.

Second, it appears that better data would have been harder to get. Schools report the number of AP tests taken, but it appears that many don’t report anything about the scores their students receive.

Given Newsweek’s questionable formula, is it picking the best schools in the U.S.? Not likely. My wife, on reading Newsweek’s list, was surprised to see Oxnard High (of Oxnard, California) ranked as the 60th best. She was born in Oxnard and went to a nearby high school, and had never thought of Oxnard High as an elite school.

(To be clear: in no way am I comparing Oxnard High to Monkey High. Oxnard High seems like a pretty typical school by U.S. standards. Many of my wife’s friends graduated from Oxnard High. But, despite what Newsweek says, it’s not one of the very best schools in the country.)

Looking at standardized test scores – the actual scores, not the percentage of students who showed up for the test – Oxnard High appears to be a bit below average among California schools. Oxnard High students had an average SAT score of 997, compared to a state average of 1012; and 23% of Oxnard students took the SAT, compared to 37% statewide. 28% of Oxnard students met University of California admissions requirements, compared to 34% statewide.

What really makes Newsweek’s formula look bad is the data on AP test scores. If we use an improved version of Newsweek’s formula – dividing the number of AP scores of 3 or above (on a 5-point scale), by the number of enrolled juniors and seniors – Oxnard High scores 0.08, compared to a state average of 0.24. Many Oxnard High students take AP tests, but few score well. These are not the statistics of a top-performing school.

Here’s my report card for Newsweek’s high school ratings:

English: Proficient
Math: Needs Work
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Nobody Disputes This Post

May 9, 2005 by

Friday’s debate between Dean Garfield (MPAA’s head lawyer) and Wendy Seltzer (EFF lawyer) at Princeton was fairly interesting. I’m hoping video will be available sometime soon.

At one point, though, Dean Garfield said something that totally floored me. He was talking about technologies like Audible Magic that claim to be able to detect and block copyrighted music as it passes across a network. He asserted that that technology would be effective in stopping infringement. That’s a pretty iffy claim already. Then he went on to assert that “nobody disputes” the effectiveness of filtering.

That’s a pretty nervy statement to make in a debate. First, it’s obviously false. To give one well-known example, the computer science professors’ amicus brief in the Grokster case disputed that very claim. Two or three signers of the brief were in the room, and one of them (me) was moderating the debate.

Second, saying “nobody disputes X” is a questionable debating tactic, since it practically invites somebody in the room to falsify your statement by disputing X. Which is exactly what I felt compelled to do. Several members of the audience told me later that they would have raised their hands and disputed the effectiveness of filtering, had I not done so.

Third, if you’re going to make a statement that nobody disputes X, you ought to be able to back it up with strong evidence in support of X. When challenged to give even one example of an ordinary site where filtering was effectively preventing infringement, Mr. Garfield was unable to respond. He also dodged the question of whether the filtering software he advocates has undergone independent testing.

So why did he say that nobody disputes the effectiveness of filtering? I can only surmise that he felt compelled to say it because it is an MPAA/RIAA talking point at the moment. The old talking point used to be that filtering works. The new version, apparently, is that everybody agrees that filtering works. The change, if indeed there is one, shows that skepticism about filtering is spreading. It’s an old lawyer’s trick to assert that a claim is undisputed, in order to avoid addressing the contrary evidence.

Still, the debate was on the whole a success. Students who had studied the issue had the chance to cross-examine the speakers. Students who had not studied the issue heard the basic points made. The best possible debate, though, would have fewer talking points from both sides.

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A View from DMP World

May 5, 2005 by

The “6th General Assembly of the Digital Media Project” recently released a set of documents “providing an Interoperable DRM Platform”. I’ve written before about the self-contradictory nature of their goal (A Perfectly Compatible Form of Incompatibility). Now we get to see how they plan to achieve the goal. And I have to say, the documents are a real piece of work. I could blog for a month just dissecting them; but I won’t subject you to that. Instead, just a small sample or two.

The documents describe a world unlike the one we actually live in. They do this, mostly, by redefining words that we all understand, creating improved versions that are distinguished typographically by capitalization. (There is a whole document devoted to definitions.) When you enter DMP-World, you give up your rights; they are replaced by Rights. And unlike ordinary rights, which you may possess simply by virtue of being a human being, Rights have to be Granted to you, and they can be Withdrawn by a Creator. In DMP-World, you can’t buy devices; all you can get are Devices. You don’t whistle a tune; you execute Functions on Governed Content. The goal of all of this is to achieve Trust: “a state where Users, Devices, or Content Data enable Users to execute Functions on Governed Content”.

All of this is done with little if any reference to copyright law. There is plenty of talk about “protection” and “intellectual property” and, of course, Rights. But not much is said about the actual scope of copyright law or its correspondence to the structure of DMP-World. Instead, DMP-World seems to redesign copyright from the ground up, replacing it with something much broader, and yet at the same time much less precise. Copyright law, for example, explains with moderate precision which types of works it covers and which it doesn’t cover. In DMP-World, the system covers Works. What is a Work? Here’s the explanation (from document 2, p. 13), which I swear I’m not making up:

The first object identified and to which IP is attributed to in the Creation Model is Work. Work refers to the fruit of an effort undertaken by an individual or group of individuals that constitutes the logical construct that persists independently of the innumerable possible physical representations of that construct. A Work on the one hand can be very concrete by being unequivocally identified through a large number of differing manifestations all of which are perceived as being of the Work yet it is also ephemeral in that proof of its existence requires the use of physically perceivable resources that are not of the Work. The Work is somewhat like an invisible hand that gives shape to a glove.

Work, it seems, it a lot like the Tao: both concrete and ephemeral, existing independently of physical manifestations, and knowable only through its tendency to give shape to the world. The Tao is even described, sometimes, using the hand/glove metaphor.

To aid your understanding, here is Lin Yutang’s translation of the first chapter of the Tao Te Ching, which does seem oddly relevant to DMP-World:

The Tao the can be told of
Is not the Absolute Tao;
The Names that can be given
Are not Absolute Names.

The Nameless is the origin of Heaven and Earth;
The Named is the Mother of All Things.

Therefore:
Oftentimes, one strips oneself of passion
In order to see the Secret of Life;
Oftentimes, one regards life with passion,
In order to see its manifest forms.

These two (the Secret and its manifestations)
Are (in their nature) the same;
They are given different names
When they become manifest.

They may both be called the Cosmic Mystery:
Reaching from the Mystery into the Deeper Mystery
Is the Gate to the Secret of All Life.

That should make things perfectly clear.

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Fear-to-Peer, Art and Science at Princeton

May 4, 2005 by

“Fear-to-Peer at Princeton: A Debate about Filesharing on Campus” will be held Friday, May 6, at 3:30 P.M., in Friend Center 101 on the Princeton campus. (directions) Dean Garfield, VP and Director of Legal Affairs at the MPAA, will square off against Wendy Seltzer, an intellectual property attorney with the EFF. I’ll be the moderator. The debate is open to the public, and we’re hoping to either webcast the debate or make a video available afterward.

The debate will be just down the hall from the amazing “Art of Science” exhibition that opened yesterday. There’s also an online version. Here’s an introduction:

This spring we asked the Princeton University community to submit imagery produced in the course of research or incorporating tools and concepts from science. The response was overwhelming: more than 200 entries from nearly 100 individuals in 15 departments. We selected 55 of these works to appear in the 2005 Art of Science Exhibition.

The resulting assembly of images presents a fascinating and beautiful cross section of the arts and sciences at Princeton. It celebrates the aesthetics of research and the ways in which science and art inform each other.

This is an especially good week to be at Princeton!

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