[Permission is granted to repost this document in its entirety, without other limitation. See http://invisiblog.com/1c801df4aee49232/ for an online copy.] The EFF has published a report on the "Promise and Risk" of Trusted Computing at http://www.eff.org/Infra/trusted_computing/20031001_tc.php. See also http://www.eff.org/Infra/trusted_computing/ for ongoing coverage of TC issues. The EFF is to be congratulated for taking its time to study the many issues revolving around TC and come to a relatively balanced and nuanced position. Staff Technologist Seth Schoen, said to be the principle author of the new report, provided some of the best early information about Palladium on his blog at http://vitanuova.loyalty.org/2002-07-05.html and similar postings, which were refreshingly objective and free of the almost obligatory anti-Microsoft bias of other analyses from so-called online rights activists. Nevertheless, the EFF report has a number of shortcomings which deserve discussion. The EFF tries to distinguish between "good" and "bad" aspects of TC, but it does not draw the line in quite the right place, even given its somewhat questionable assumptions. It fails to sufficiently emphasize the many positive uses of the full version of TC (and hence the costs of blocking its implementation), and also misses some important negatives as well. And the recommended fix to TC is not clearly described and as written appears to be somewhat contradictory. But let us begin with some positive elements of the EFF report. This is perhaps the first public, critical analysis of TC which fails to include two of the worst lies about the technology, lies promulgated primarily by Ross Anderson and Lucky Green: that only authorized programs can run "trusted", and that unauthorized or illegal programs and data will be deleted from computers or prevented from running. The EFF appears to recognize the key feature of TC, which gives it its name: that trust is in the eye of the truster. Anyone can create code which benefits from TC features, and it is up to the user of a computer to decide which local and remote software he will trust. The report also forthrightly rejects the claim that TC technology is some kind of trick to defeat Linux or lock-in computers to Microsoft operating systems, and debunks the lie put forth by Lucky Green that TC will insert spyware into your computer. By choosing to emphasize the truth rather than lies on these important points, the EFF gains credibility at the expense of opening itself to charges by extremists that it is in bed with Microsoft or is promoting "evil" technology. Those of us who have argued in the past for balanced analyses of TC are well aware of the speed with which opponents resort to name-calling and personal attacks, and it is a credit to the EFF that they have taken a courageous position which departs from the conventional wisdom in the online rights community. Despite these positives, as noted above the report has some weaknesses which need to be addressed. The EFF attempts to distinguish one feature of TC, remote attestation, as a source of problems. This is the ability of a computer user to convince other systems about what software he is running. The EFF is convinced that this feature will cause users to be compelled to use software not of their choice; harm interoperability and encourage lock-in; and support DRM and various restrictive kinds of licensing. But when we break these down in detail, many of the problems either go away or are not due to attestation. Software choice limitation may occur if a remote system provides some service conditional on the software being used to access it. But that's not really a limitation of choice, because the user could always elect not to receive the offered service. The implicit assumption here seems to be that if TC did not exist, the service would be offered without any limitations. Then it makes it appear that TC adds limitations which are not currently present. But what this analysis overlooks is that TC will allow the creation of new services which are not economically possible today. By allowing for more protection of data, a whole host of new applications may become possible. So the proper comparison is not with a hypothetical state where you'd have all the same services without TC as with; but rather, comparing a TC world that is relatively rich in services with a service-poor non-TC world. Turning to the issues of lock-in and interoperability, it is true that TC may allow software creators to lock their data to the applications and make it more difficult to create interoperable alternatives, thus promoting lock-in. The problem here with the EFF analysis is that it is not the remote attestation feature of TC which is the primary cause of this effect, but rather it is the sealed storage feature. It is sealed storage that allows data to be encrypted such that only one particular application can decrypt it, and potentially makes it impossible to switch to a different software package, or access the data in an interoperable way. The EFF attempts to say that sealed storage and other features of TC are good, because they clearly can increase the security features of your computer. Then they draw a line at remote attestation. But if it is lock-in and interoperability that worries them, sealed storage has to go as well. This inconsistency in the report undercuts its main conclusion. And parenthetically, lock-in is not necessarily a bad thing, as long as people know about it in advance. When you go on vacation you know that you will only be able to eat at restaurants in the local area. You are locked-in to local eateries. Everyone accepts this as part of the cost of the vacation. People can factor these kinds of lock-in costs into the overall package when they make decision about what to buy, whether travel or software. In this sense, it's good for activists like the EFF to make people aware that TC may increase lock-in, but they should put the issue into perspective and not present it as a reason to abandon the technology. It's just a consideration to be aware of when buying any software that is TC-enabled. Lastly, the EFF is worried that remote attestation enables DRM and other restrictive licensing practices. This is clearly true, although things are not quite as simple as they seem. Before wide-scale use of TC for DRM, it will be necessary for the manufacturers, software vendors and content providers to get past a few tiny details, like setting up a global, universal, widely trusted and secure PKI. Hopefully readers in these forums will understand that this is not exactly a trivial problem. Going from the basic technological definitions of TC to the massive infrastructure of keys and revocations needed for a secure, commercial DRM system and other licensing schemes is going to take quite a while. But in any case, once it happens, again the report fails to paint a balanced picture, by emphasizing the negative aspects of the new kinds of licensing that TC will enable. It should be clear that a technology that allows new kinds of voluntary arrangements, without eliminating any old ones, cannot be entirely evil. TC only expands the space of possibilities, it does not stop anyone from doing things the old way. If the new possibilities enabled by TC are truly so horrible for consumers, and if it is possible (as TC opponents implicitly assume) to provide these functionalities without the nightmarish limitations that the report is so afraid of, then some companies can still offer their goods under those more-favorable terms, and reap massive rewards as consumers triumphantly reject the horrific license terms of the TC-based software. This report, like so many others, ignores the role of consumers in making decisions about what technologies to use. This is one area in which the EFF was unable to rise above the myopia shared by so many other analyses. Ironically, given these oversights, the report also manages to miss some bad features of TC, features which have been discussed at some length on the cypherpunks and cryptography mailing lists. One of the biggest is the area of upgrades and system replacement. The TCPA (now TCG) proposal for handling upgrades is clearly unworkable, and Microsoft has said nothing about how they will do it. Any data which is locked to your computer is clearly at greater risk of being unrecoverable if your computer breaks. Until a bulletproof upgrade path exists, end users are going to be reluctant to embrace the promise of TC technology. Another area not discussed is the risk to privacy implicit in using this technology on a global network. TCPA's solution, "privacy CAs", is another part of the spec that is obviously never going to work. Microsoft had made some noise about copying this at one point, and is now decidedly mute on the issue. It is an almost impossible problem to solve, and chances are that the companies will simply give up and let the system compromise user privacy. As a privacy-oriented watchdog group, the EFF has dropped the ball in failing to emphasize this point. The final complaint about the report is that their solution doesn't seem to make sense. The basic idea is to allow the user to override the remote attestation feature so his system can lie about his software configuration. The apparent problem with this, as a number of commentators have pointed out, is that it undercuts the remote attestation feature and makes it useless. It is like "fixing" the limitations of cryptographic certificates by allowing anyone to forge them. Doing this defeats the purpose of the feature so completely that you might as well not have it. It would seem to make more sense for the EFF to simply call for remote attestation to be removed from the TC concept than to try to come up with a complicated "owner override". And in fact it seems likely that remote attestation will be one of the last parts of the TC spec to be implemented due to the PKI problem noted above, so we will probably see TC installations initially without attestation support. It may be that remote attestation never becomes as popular as TC proponents hope and critics fear. Now, perhaps there are some subtle aspects to the EFF proposal which would make attestation with owner overrides more useful than a version of TC without attestation at all. But to analyze that we'd need more detail about how exactly this owner override is supposed to work, and what attestation would still be used for in such a system. As it is, the proposal is frustratingly vague on these details. Summing up, the EFF report manages avoid the worst excesses of anti-TC rhetoric so common in the online rights community. By attempting to take a moderate course and identifying both promise and risk with TC technology, it does a service in setting a new standard of accuracy and civility in analyzing this important topic. However the report does have weaknesses, and its attempt to focus on problems with remote attestation misunderstands both economic realities and the technical details of which aspects of TC cause problems. By concentrating so narrowly on attestation, the EFF overlooks both important risks and promises of this new technology. And its proposed solution appears illogical on its face, requiring much more explanation and discussion for a fair evaluation. Make no mistake about it: TC is coming. All the rhetoric, all the protests and objections, are doing nothing to alter the apparently unstoppable momentum of this new technology. Microsoft is committed to NGSCB (Palladium), and the TCG (TCPA) is working actively on specs for cell phones and other devices. There is even considerable work to bring TC into Linux. What we need now is better understanding of both the risks and rewards of this technology, which will be here perhaps sooner than many of us expect. The EFF report is a good first step in this direction, but the problems need to be corrected. And rather than a futile and quixotic attempt to change the nature of TC, the EFF should focus on informing consumers about the pros and cons of the system, how it will affect their use of technology in years to come, questions to ask of vendors, and ways to protect their privacy and security. That is a hard enough task, and one truly in keeping with the EFF's goals and mission.