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HD-DVD Requires Digital Imprimatur

July 18, 2005 by

Last week I wrote about the antitrust issues raised by the use of encryption to “protect” content. Here’s a concrete example.

HD-DVD, one of the two candidates for the next-gen DVD format, uses a “content protection” technology called AACS. And AACS, it turns out, requires a digital imprimatur on any content before it can be published.

(The imprimatur – the term is Latin for “let it be printed” – was an early technology of censorship. The original imprimatur was a stamp of approval granted by a Catholic bishop to certify that a work was free from doctrinal or moral error. In some times and places, it was illegal to print a work that didn’t have an imprimatur. Today, the term refers to any system in which a central entity must approve works before they can be published.)

The technical details are in the AACS Pre-recorded Video Book Specification. The digital imprimatur is called a “content certificate” (see p. 5 for overview), and is created “at a secure facility operated by [the AACS organization]” (p. 8 ). It is forbidden to publish any work without an imprimatur, and player devices are forbidden to play any work that lacks an imprimatur.

Like the original imprimatur, the AACS one can be revoked retroactively. AACS calls this “content revocation”. Every disc that is manufactured is required to carry an up-to-date list of revoked works. Player devices are required to keep track of which works have been revoked, and to refuse to play revoked works.

The AACS documents avoid giving a rationale for this feature. The closest they come to a rationale is a statement that the system was designed so that “[c]ompliant players can authenticate that content came from an authorized, licensed replicator” (p. 1). But the system as described does not seem designed for that goal – if it were, the disc would be signed (and the signature possibly revoked) by the replicator, not by the central AACS organization. Also, the actual design replaces “can authenticate” by “must authenticate, and must refuse to play if authentication fails”.

The goal of HD-DVD is to become the dominant format for release of movies. If this happens, the HD-DVD/AACS imprimatur will be ripe for anticompetitive abuses. Who will decide when the imprimatur will be used, and how? Apparently it will be the AACS organization. We don’t know how that organization is run, but we know that its founding members are Disney, IBM, Intel, Microsoft, Panasonic, Sony, Toshiba, and Warner Brothers. A briefing on the AACS site explains the “AACS Structure” by listing the founders.

I hope the antitrust authorities are watching this very closely. I hope, too, that consumers are watching and will vote with their dollars against this kind of system.

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Controlling Software Updates

July 14, 2005 by

Randy Picker questions part of the computer science professors’ Grokster brief (of which I was a co-signer), in which we wrote:

Even assuming that Respondents have the right and ability to deliver such software to end users, there can be no way to ensure that software updates are installed, and stay installed. End users ultimately have control over which software is on their computers. If an end user does not want a software update, there is no way to make her take it.

This point mattered because Hollywood had suggested that Grokster should have used its software-update facility to deploy filtering software. (Apparently there is some dispute over whether Grokster had such a facility. I don’t know who is right on that factual question.)

Picker wonders whether ordinary users can really exercise this control in practice. As he notes, the user can disconnect from the net, but that’s too high a price for most people to pay. So how can users prevent updates?

The easiest method is simply to write-protect the program’s files or directories, so that they can’t be changed. Alternatively, the user can make a backup copy of the software (perhaps by copying it to another directory) and restore the backup when an update is installed.

Standard system security tools are also useful for controlling automatic updates. Autonomously self-updating programs look a lot like malicious code – the program code changes on its own (like a virus infection); the program makes network connections to odd places at odd times (like spyware); the program downloads and installs code without asking the user (like a malicious bot). Security tools specialize in identifying and blocking such behaviors, and the tools are reasonably configurable. Personal firewalls, for example, can block a program from making unapproved network connections. Some firewalls even do this by default.

Finally, a skilled person can figure out how to patch the program to disable the auto-update feature. He can then encapsulate this knowledge in a simple tool, so that other users can disable their auto-update by downloading the tool and double-clicking it. (This tool may violate copyright by modifying the program; but if we trusted users to obey copyright law we wouldn’t be having this conversation.)

The bottom line is that in computer security, possession is nine-tenths of control. Whoever has physical access to a device can control what it does. Whoever has physical control of a computer can control what software is installed on it. And users have physical control of their PCs.

A followup question is whether you can program the software to shut itself off if the user blocks updates for too long. As far as I know, nobody is claiming that Grokster had such a capability, but in principle a P2P system could be designed to (try to) work that way. This raises interesting issues too, but I’m approaching my word count limit so I’ll have to address them another day.

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Michigan Email Registry as a Tax on Bulk Emailers

July 13, 2005 by

I wrote on Friday about the new registry of kids’ email addresses being set up by the state of Michigan. I wasn’t impressed. A commenter pointed out an important fact I missed: emailers have to pay a fee of $0.007 to screen each address against the list.

(One of the occupational hazards of blogging is the risk of posting without meticulous research. Fortunately such oversights can be corrected, as I’m doing here. My apologies to readers who were temporarily misled.)

I still worry that the list will leak information about kids’ email addresses to emailers. The fee will raise the cost of fishing expeditions designed to guess which addresses are on the list, to the point where it probably won’t be worthwhile for an emailer to launch blind guessing attacks. But emailers will still learn the status of addresses that are already on their lists.

The main effect of the fee is to turn the whole program into a tax on bulk emailing. The tax operates even if only a few kids’ addresses are registered, so parents worried about leaking their kids’ addresses can safely decline to register them. So let’s look at this as a tax scheme rather than a child protection program.

It’s an oddly structured tax, charging a bulk emailer $0.007 for each email address he mails to within a thirty-day period. (Emailers must re-check their lists every thirty days to avoid a violation.) And it only applies to bulk emailers who promote products that kids aren’t allowed to own. That includes some products whose promotion the state is particularly eager to control (e.g., drugs and gambling) as well as some products that are innocuous but inappropriate for kids (e.g., vehicles).

Why isn’t this structured simply as a tax on bulk email? We’d have to ask a free speech lawyer to be sure, but I wonder whether a tax on speech, and especially a tax that applies only to some kinds of speech, would be constitutionally suspect. Connecting it to the state interest in protecting kids from harmful commercial speech may provide some cover. (I could be off base here. If so, I’m sure commenters will set me straight.)

The tax seems unlikely to generate much revenue for the state. Including administrative costs, it may cost the state money. Presumably the goal is to change emailers’ incentives.

The incentive effect on outlaw spammers will be zero. They’ll just ignore this law, and add it to the list of laws they are already violating.

Gray hat spammers, who operate aboveboard and call themselves legitimate businesspeople, will see their costs increase. The tax will impose a fixed cost per address on their list, but independent of the number of messages sent to that address within a month. Adding to fixed costs will tend to cause consolidation in the gray hat spammer business – if two spammers share a list, they’ll only have to pay the tax once. It’s getting harder and harder to be a gray hat spammer already; this will only squeeze the gray hats further.

With the tax angle added, the Michigan program might turn out to be good policy. But I still wouldn’t register my own kid.

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Encryption and Copying

July 12, 2005 by

Last week I criticized Richard Posner for saying that labeling content and adding filtering to P2P apps would do much to reduce infringement on P2P net. In responding to comments, Judge Posner unfortunately makes a very similar mistake:

Several pointed out correctly that tags on software files, indicating that the file is copyrighted, can probably be removed; and this suggests that only encryption, preventing copying, is likely to be effective in protecting the intellectual property rights of the owner of the copyright.

The error is rooted in the phrase “encryption, preventing copying”. Encryption does nothing to prevent copying – nor is it intended to. Encrypted data can be readily copied. Once decrypted, the plaintext data can again be readily copied. Encryption prevents one and only one thing – decryption without knowledge of the secret key.

It’s easy to see, then, why encryption has so little value in preventing infringement. You can ship content to customers in encrypted form, and the content won’t be decrypted in transit. But if you want to play the content, you have to decrypt it. And this means two things. First, the decrypted content will exist on the customer’s premises, where it can be readily copied. Second, the decryption key (and any other knowledge needed to decrypt) will exist on the customer’s premises, where it can be reverse-engineered. Either of these facts by itself would allow decrypted content to leak onto the Internet. So it’s not surprising that every significant encryption-based anticopying scheme has failed.

We need to recognize that these are not failures of implementation. Nor do they follow from the (incorrect) claim that every code can be broken. The problem is more fundamental: encryption does not stop copying.

Why do copyright owners keep building encryption-based systems? The answer is not technical but legal and economic. Encryption does not prevent infringement, but it does provide a basis for legal strategems. If content is encrypted, then anyone who wants to build a content-player device needs to know the decryption key. If you make the decryption key a trade secret, you can control entry to the market for players, by giving the key only to acceptable parties who will agree to your licensing terms. This ought to raise antitrust concerns in some cases, but the antitrust authorities have not shown much interest in scrutinizing such arrangements.

To his credit, Judge Posner recognizes the problems that result from anticompetitive use of encryption technology.

But this in turn presents the spectre of overprotection of [copyright owners’] rights. Copyright is limited in term and, more important (given the length of the term), is limited in other ways as well, such as by the right to make one copy for personal use and, in particular, the right of “fair use,” which permits a significant degree of unauthorized copying. To the extent that encryption creates an impenetrable wall to copying, it eliminates these limitations on copyright. In addition, encryption efforts generate countervailing circumvention efforts, touching off an arms race that may create more costs than benefits.

Once we recognize this landscape, we can get down to the hard work of defining a sensible policy.

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RIAA Saber-Rattling against Antispoofing Technologies?

July 11, 2005 by

The RIAA has fired a shot across the bow of P2P companies whose products incorporate anti-spoofing technologies, according to a story (subscribers only) in Friday’s National Journal Tech Daily, by Sarah Lai Stirland. The statement came at a Washington panel on the implications of the Grokster decision.

“There’s definitely a lot of spoofing going on on the networks, and nobody thinks that that’s not fair game,” said Cary Sherman, president of the Recording Industry Association of America, on Friday. “Some networks actually put out some anti-spoofing filters to enable people to get around the spoofs, and that may well be a sign of intent.”

…

The comment came in answer to a question about the kinds of lawsuits that might be brought in the wake of the high court’s decision.

What Sherman is suggesting is that if a P2P vendor includes anti-spoofing technology in their product, that action demonstrates an intent to facilitate infringement, making the vendor liable as an indirect infringer under Grokster.

Perhaps Sherman is asserting that anti-spoofing technologies lack substantial noninfringing uses, and so do not qualify for the Sony Betamax safe harbor. This is wrong in general. It’s well known that some of the files on P2P systems are of low audio or video quality, or are mislabelled altogether. This is true of both infringing and non-infringing files. A technology that can predict which files will have low quality, or which users will be sources of low quality files, will help users find what they want. Spoof files are just low quality files that are inserted deliberately, so technologies that reject low-quality files will tend to reject spoof files, and vice versa.

Of course some particular vendor might introduce such a filter for bad reasons, because they want to abet infringement. But one cannot infer such intent merely from the presence of the filter.

One popular interpretation of Grokster is that the Court said a company’s overall business practices, rather than its technology, will determine its liability. That seems to follow from the Court’s refusal to revise the Sony Betamax rule. And yet Sherman’s complaint here is all about technology choices. Is this the precursor to lawsuits against undesired technologies?

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