By Bruce Schneier
Wednesday, August 31 2005 05:42 PM
URL: http://www.zdnetasia.com/insight/security/0,39044829,39251841,00.htm

perspective The Trusted Computing Group is an industry consortium that's trying to build more secure computers.

It has a lot of members, although the board of directors consists of Microsoft, Sony, Advanced Micro Devices, Intel, IBM, Sun Microsystems, Hewlett-Packard and two smaller companies that are voted in on a rotating basis.

The basic idea is that you build a computer from the ground up securely, with a core hardware "root of trust" called a Trusted Platform Module, or TPM. Applications can run securely on the computer, communicate with other applications and their owners securely, and be sure that no untrusted applications have access to their data or code.

This sounds great, but it's a double-edged sword. The same system that prevents worms and viruses from running on your computer might also stop you from using any legitimate software that your hardware or operating system vendor simply doesn't like. The same system that protects spyware from accessing your data files might also stop you from copying audio and video files. The same system that ensures that all the patches you download are legitimate might also prevent you from, well, doing pretty much anything.

(Ross Anderson has an excellent FAQ on the topic. I wrote about it back when Microsoft called the system Palladium.)

In May, the Trusted Computing Group published a best practices document: Design, Implementation, and Usage Principles for TPM-Based Platforms . Written for users and implementers of TCG technology, the document tries to draw a line between good uses and bad uses of this technology.

The principles that TCG believes underlie the effective, useful and acceptable design, implementation and use of TCG technologies are the following:

•  Security: TCG-enabled components should achieve controlled access to designated critical secured data and should reliably measure and report the system's security properties. The reporting mechanism should be fully under the owner's control.

•  Privacy: TCG-enabled components should be designed and implemented with privacy in mind and adhere to the letter and spirit of all relevant guidelines, laws and regulations. This includes, but is not limited to, the OECD Guidelines, the Fair Information Practices and the European Union Data Protection Directive (95/46/EC).

If the document isn't published until after Vista is released, then obviously it doesn't apply.

•  Interoperability: Implementations and deployments of TCG specifications should facilitate interoperability. Furthermore, implementations and deployments of TCG specifications should not introduce any new interoperability obstacles that are not for the purpose of security.

•  Portability of data: Deployment should support established principles and practices of data ownership.

•  Controllability: Each owner should have effective choice and control over the use and operation of the TCG-enabled capabilities that belong to them; their participation must be opt-in. Subsequently, any user should be able to reliably disable the TCG functionality in a way that does not violate the owner's policy.

•  Ease-of-use: The nontechnical user should find the TCG-enabled capabilities comprehensible and usable.

It's basically a good document, although there are some valid criticisms. I like that the document clearly states that coercive use of the technology--forcing people to use digital rights management systems, for example--is inappropriate.

•  The use of coercion to effectively force the use of the TPM capabilities is not an appropriate use of the TCG technology.

I like that the document tries to protect user privacy:

•  All implementations of TCG-enabled components should ensure that the TCG technology is not inappropriately used for data aggregation of personal information.

I wish that interoperability were more strongly enforced. The language has too much wiggle room for companies to break interoperability under the guise of security:

•  Furthermore, implementations and deployments of TCG specifications should not introduce any new interoperability obstacles that are not for the purpose of security.

That sounds good, but what does "security" mean in that context? Security of the user against malicious code? Security of big media against people copying music and videos? Security of software vendors against competition? The big problem with TCG technology is that it can be used to further all three of these "security" goals, and this document is where "security" should be better defined.

Complaints aside, it's a good document and we should all hope that companies follow it. Compliance is totally voluntary, but it's the kind of document that governments and large corporations can point to and demand that vendors follow.

But there's something fishy going on. Microsoft is doing its best to stall the document, and to ensure that it doesn't apply to Vista, Microsoft's next-generation operating system.

The document was first written in the fall of 2003, and went through the standard review process in early 2004. Microsoft delayed the adoption and publication of the document, demanding more review. Eventually, the document was published in June of this year (with a May date on the cover).

Meanwhile, the TCG built a purely software version of the specification: Trusted Network Connect (TNC). Basically, it's a TCG system without a TPM.

The best-practices document doesn't apply to TNC, because Microsoft (as a member of the TCG board of directors) blocked it. The excuse is that the document hadn't been written with software-only applications in mind, so it shouldn't apply to software-only TCG systems.

This is absurd. The document outlines best practices for how the system is used. There's nothing in it about how the system works internally. There's nothing unique to hardware-based systems, nothing that would be different for software-only systems. You can go through the document yourself and replace all references to "TPM" or "hardware" with "software" (or, better yet, "hardware or software") in five minutes. There are about a dozen changes, and none of them make any meaningful difference.

The only reason I can think of for all this Machiavellian maneuvering is that the TCG board of directors is making sure that the document doesn't apply to Vista. If the document isn't published until after Vista is released, then obviously it doesn't apply.

Near as I can tell, no one is following this story. No one is asking why TCG best practices apply to hardware-based systems if they're writing software-only specifications. No one is asking why the document doesn't apply to all TCG systems, since it's obviously written without any particular technology in mind. And no one is asking why the TCG is delaying the adoption of any software best practices.

I believe the reason is Microsoft and Vista, but clearly there's some investigative reporting to be done.

biography
Bruce Schneier is CTO of Counterpane Internet Security, Inc. He is one of the world's foremost security experts. His latest book is "Beyond Fear: Thinking Sensibly About Security in an Uncertain World."