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RIAA Says Future DRM Might "Threaten Critical Infrastructure and Potentially Endanger Lives"

March 8, 2006 by

We’re in the middle of the U.S. Copyright Office’s triennial DMCA exemption rulemaking. As you might expect, most of the filings are dry as dust, but buried in the latest submission by a coalition of big copyright owners (publishers, Authors’ Guild, BSA, MPAA, RIAA, etc.) is an utterly astonishing argument.

Some background: In light of the Sony-BMG CD incident, Alex and I asked the Copyright Office for an exemption allowing users to remove from their computers certain DRM software that causes security and privacy harm. The CCIA and Open Source and Industry Association made an even simpler request for an exemption for DRM systems that “employ access control measures which threaten critical infrastructure and potentially endanger lives.” Who could oppose that?

The BSA, RIAA, MPAA, and friends – that’s who. Their objections to these two requests (and others) consist mostly of lawyerly parsing, but at the end of their argument about our request comes this (from pp. 22-23 of the document, if you’re reading along at home):

Furthermore, the claimed beneficial impact of recognition of the exemption – that it would “provide an incentive for the creation of protection measures that respect the security of consumers’ computers while protecting the interests of the record labels” ([citation to our request]) – would be fundamentally undermined if copyright owners – and everyone else – were left in such serious doubt about which measures were or were not subject to circumvention under the exemption.

Hanging from the end of the above-quoted excerpt is a footnote:

This uncertainty would be even more severe under the formulations proposed in submissions 2 (in which the terms “privacy or security” are left completely undefined) or 8 [i.e., the CCIA request] (in which the boundaries of the proposed exemption would turn on whether access controls “threaten critical infrastructure and potentially endanger lives”).

You read that right. They’re worried that there might be “serious doubt” about whether their future DRM access control systems are covered by these exemptions, and they think the doubt “would be even more severe” if the “exemption would turn on whether access controls ‘threaten critical infrastructure and potentially endanger lives’.”

Yikes.

One would have thought they’d make awfully sure that a DRM measure didn’t threaten critical infrastructure or endanger lives, before they deployed that measure. But apparently they want to keep open the option of deploying DRM even when there are severe doubts about whether it threatens critical infrastructure and potentially endangers lives.

And here’s the really amazing part. In order to protect their ability to deploy this dangerous DRM, they want the Copyright Office to withhold from users permission to uninstall DRM software that actually does threaten critical infrastructure and endanger lives.

If past rulemakings are a good predictor, it’s more likely than not that the Copyright Office will rule in their favor.

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USACM Policy Statement on DRM

March 6, 2006 by

I’m pleased to post here a new policy statement on DRM, issued by USACM, the U.S. public policy committee of ACM, the leading professional society for computer scientists. It’s a balanced yet strong statement of principles that can be applied to many public policy questions relating to DRM. I helped to draft it, and I support it. USACM has posted the original document in PDF format.

USACM is a valuable resource on infotech policy issues. And they have a useful policy blog too.

USACM Policy Recommendations on Digital Rights Management

February 2006

BACKGROUND:

New technologies have remade the consumer entertainment landscape, allowing creative content – such as movies, television, and radio programming – to be delivered in digital form. Because exact copies of digital content can be widely and quickly distributed, some content distributors are employing technical protection systems to manage consumer uses of copyrighted content, often characterized as “digital rights management (DRM)” technology. DRM systems are intended to enable distributors to manage consumer uses of content. In theory, this may prevent the making and distribution of infringing copies of digital works. However, use of these technologies has created controversy, especially as regards issues of “fair use” and public interest. In some cases, DRM technologies have been found to undermine consumers’ rights, infringe customer privacy, and damage the security of consumers’ computers. One notable example was the software distributed with compact discs in 2005 by Sony BMG. Sony subsequently withdrew the product, which had created security and privacy vulnerabilities for consumers’ computers, because of resulting public criticism and legal action.

The marketplace should determine the success or failure of DRM technologies but, increasingly, content distributors are turning to legislatures or the courts to erect new legal mandates to replace long-standing copyright regimes. DRM systems should be mechanisms for reinforcing existing legal constraints on behavior, not as mechanisms for creating new legal constraints. Striking a balance among consumers’ rights, public interest, and protection of valid copyright interests is no simple task for technologists or policymakers. For this reason, USACM has developed the following recommendations on this important issue.

RECOMMENDATIONS:

Competition: Public policy should enable a variety of DRM approaches and systems to emerge, should allow and facilitate competition among them, and should encourage interoperability among them. No proprietary DRM technology should be mandated for use in any medium.

Copyright Balance: Because lawful use (including fair use) of copyrighted works is in the public’s best interest, a person wishing to make lawful use of copyrighted material should not be prevented from doing so. As such, DRM systems should be mechanisms for reinforcing existing legal constraints on behavior (arising from copyright law or by reasonable contract), not as mechanisms for creating new legal constraints. Appropriate technical and/or legal safeguards should be in place to preserve lawful uses in cases where DRM systems cannot distinguish lawful uses from infringing uses.

Consumer Protection: DRM should not be used to interfere with the rights of consumers. Neither should DRM technologies interfere with any technology or use of consumer systems that are unrelated to the copyrighted items being managed. Policymakers should actively monitor actual use of DRM and amend policies as necessary to protect these rights and interests.

Privacy and Consent: Public policy should ensure that DRM systems may collect, store, and redistribute private information about users only to the extent required for their proper operation, that they follow fair information practices, and that they are subject to informed consent by users.

Research and Public Discourse: DRM systems and policies should not interfere with legitimate research, with discourse about research results, or with other matters of public concern. Laws and regulations concerning DRM should contain explicit provisions to protect this principle.

Targeted Policies: Public policies meant to reinforce copyright should be limited to applications where copyright interests are actually at stake. Laws and regulations concerning DRM should have limited scope, applying only where there is a realistic risk of copyright infringement.

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How Watermarks Fail

February 24, 2006 by

I wrote Wednesday about Randy Picker’s suggestion of using digital watermarks to embed users’ personal financial information into media files, to discourage users from sharing the files. Today, I want to talk more generally about watermarks and how they tend to fail.

First, some background. Watermarks are subtle signals embedded in the background of media files. They are supposed to be unobtrusive but easy to detect if you know where to look. Different media have different kinds of watermarks. In a photo, the watermark might be hidden in subtle patterns of shading. In music, it might be in a very soft background buzz, or a barely audible echo.

In many applications, a watermark must resist attempts by an adversary to remove it. For example, in Randy’s scheme, a user might want to remove the identifying watermark from a media file because he wants to share the file illegally, or because he doesn’t want his personal information exposed to cyber-intruders. It is often important to know how resistant a particular watermark is to removal. There has been plenty of research on this topic, from which we can draw lessons about how watermark removal tends to work.

One theme is the power of Rosetta Stone attacks. The original Rosetta Stone was a stone tablet with the same text written in three ancient languages. This gave scholars who understood one of the languages a big boost in deciphering another one that they didn’t understand. Similarly, watermarks tend to be defeated if an adversary can get his hands on a watermarked file, and the same file without the watermark. By comparing the two, the adversary can determine where the watermark lives, which is usually sufficient to remove the watermark from other files. Alex used this method in deciphering the MediaMax watermark (as described in our Sony CD DRM paper), and my colleagues and I used it also in analyzing the SDMI watermarks back in 2000.

Almost as powerful as a Rosetta Stone attack is a comparison attack, where the adversary does not have an unwatermarked file, but does have the same file with several different watermarks in it. Any place where two of the files differ is a place where watermark information lives. Given several marked files, an attacker can locate all or most of the places the watermark is hidden, which is again the first step in removing the watermark.

(In theory it might be possible to stop an adversary with access to a limited number of individually watermarked files from completely removing the watermark, if the watermark has lots of places to hide and is constructed cleverly. There is an interesting body of theory about how to do this and when it works. But in practice the assumptions underlying that theory rarely hold.)

Even if the adversary cannot get access to multiple versions of a file (so that Roseta Stone or comparison attacks are not possible), he can usually still defeat a watermark if he has access to a device that can detect watermarks. By reverse engineering the device, he can figure out where it is looking for the watermark, which again puts him in a position to remove it. (Even if he can’t dissect the device, he can use it as an oracle that tells him whether a particular file has a detectable watermark. Oracles are very helpful in attacking watermarks – Alex used one in his MediaMax watermark analysis, and my colleagues and I used one in our SDMI analysis.)

All of this helps us to understand where watermarks are likely to be effective and where they’re not. The best case for watermarking is where each file is published in a single version, with a watermark in a location that is not disclosed to the public and is not implemented in a device available to the public. This would hold true, for example, in a system that put a distinctive mark into all released versions of a file, and then looked for such watermarks in content broadcast on the radio or TV or downloaded from the net.

Not nearly as strong is a system where there is a single watermark per file, and consumer devices check for the mark – it is subject to reverse engineering and oracle attacks.

Weaker yet is a system where files are watermarked individually for each consumer – it is subject to comparison attacks.

Weakest of all is a system where files are watermarked individually for each consumer and everyone is told how to read the watermarks. Here the adversary can use comparison attacks, and reverse engineering is not even necessary because the inner working of the watermark detector are well known.

Alert readers will have noticed that all of the uses of watermarks for DRM (copy protection) seem to fall into the weak categories. That is because DRM applications require either that all devices check for the watermark – opening up reverse engineering and oracle attacks – or alternatively that a file be given separate watermarks for separate consumers – opening up comparison attacks. Watermarking has its uses, but it doesn’t seem well suited for DRM.

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Mistrust-Based DRM

February 22, 2006 by

Randy Picker has an interesting post on the Chicago Law Faculty blog, describing what he calls “mistrust-based DRM”. The idea is that when an online music store gives you a song, it embeds into the song a watermark that contains your credit card number, or some other information that would let a (dishonest) person spend your money. This gives you an incentive not to distribute the song.

This is an instructive idea, but not a practical one.

In analyzing this idea, it’s helpful to divide it into two pieces: (1) embed a watermark that identifies the user, and (2) make that watermark a secret of the user and readable by the anyone who gets the file. Piece (1), taken alone, is a widely discussed DRM strategy which has not been used much in practice, for reasons I plan to discuss tomorrow. Today, I want to focus on the second piece.

Specifically, I want to compare two systems. In the more traditional system, the watermark is secret – it can be read only by the copyright owner or its agents – and users fear being sued for infringement if their files end up on P2P. In Randy’s system, the watermark is public – anybody can read it – and users fear being victimized by fraud if their files end up on P2P. I’ll call these two alternatives “secret-watermark” and “public-watermark”.

How do they compare? For starters, a secret watermark is much harder for an adversary to find and remove. If a watermark is public, everybody knows exactly where in the music it is stored. Common sense, and experience too, says that if you know where in a file information is stored, you can modify that part of the file and obliterate the information. But if the watermark is secret, then an adversary isn’t told where to look for it or how to change the file to remove it. Robustness of the watermark is an important issue that has been the downfall of past watermark systems.

A bigger problem with the public-watermark design, I think, are the forces unleashed when your design principle is to enable fraud. For example, the system will lose its force if unrelated anti-fraud measures become more effective, or if the financial system acts to protect users from fraud. Today, a consumer’s liability for fraudulent credit card transactions is capped at $50, and credit card companies often forgive even that $50. (You could use some other account information instead of the credit card number, but similar issues would still apply.) Copyright owners would be the only online merchants who wanted a higher level of fraud on the Net.

Worse yet, even law-abiding consumers would face a higher risk of fraud, because any loss or theft of their music or movie files would expose their financial information. Spyware programs could collect this information from users’ computers – and studies show that at least half of end-user PCs are infected with spyware. Law-abiding users would have a strong incentive to scrub the information out of their files, even if they had no intention of infringing. Alert anti-virus or anti-spyware vendors would be eager to provide this service.

Given the disadvantages of a public-watermark scheme, what are the arguments for it? Randy Picker argues that it gives end users an incentive to distrust fly-by-night purveyors of ripping software, worrying that they might steal the user’s information from the files and commit fraud. This isn’t entirely convincing: some such tools already contain heinous spyware that could cause users lots of harm, and reputable security suppliers are likely to provide watermark-scrubbing tools anyway. I think the threat of secret watermarks hidden in files, which fly-by-night vendors have no incentive to remove, would probably scare users enough.

On the whole, then, I think a secret-watermark scheme is better than a public-watermark one. But it should be noted that secret-watermark schemes themselves aren’t looking too good. They have mostly failed in the market, for reasons I’ll start digging into tomorrow.

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Sony CD DRM Paper Released

February 14, 2006 by

Today Alex and I released our paper about the Sony CD DRM episode. This is the full, extended version of the paper, with a bunch of new material that hasn’t been published or posted before.

As an experiment, we posted draft sections of the paper here and asked readers for comments and feedback. The experiment was a success, giving us lots of good comments and suggestions that helped us improve the paper. Several reader-commenters are thanked in the paper’s acknowledgments section.

We also asked readers to help suggest a title for the paper. That didn’t work out so well – some suggestions were entertaining, but none were really practical. Perhaps a title of the sort we wanted doesn’t exist.

Enjoy the paper, and thanks for your help.

[UPDATE (Feb. 21): If you don’t like PDFs, you can now read the paper in your browser, thanks to an HTML+images version created by Jesse Weinstein.]

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