My collegaue Seth Schoen has written an audacious article for Linux Journal in which he calls on the architects of "Trusted Computing" [TCPA|TCG|Palladium|NGSCB] systems — which ostensibly solve some of the Internet's security problems by adding cryptographicallly secured tamper-detection to the hardware of the commodity PC — to add a feature that he calls "Owner Override."
Trusted Computing proposals have drawn fire as tools for lock-in and other anti-competitive strategies; Seth's Owner Override allows the owner of a computer to override the Trusted Computing security when it is in her own interest.
For example, you could use Owner Override to tell a "lie" to your bank, which insists that you use Microsoft Internet Explorer to access its website, and convince the bank's webserver that your copy of Opera or Safari or Mozilla is really Internet Explorer. This is possible (even routine) today, but in a Trusted Computing universe, it will be impossible, modulo Owner Override.
Fortunately, this problem is fixable. TCG should empower computer owners to override attestations deliberately to defeat policies of which they disapprove. Giving the owner this choice preserves an essential part of the status quo: third parties can never know for sure what's running on your PC. TCG already defines a platform owner concept. The TCG specification also should provide for a facility by which the platform owner, when physically present, can force the TPM chip to generate an attestation as if the Platform Configuration Registers (PCRs) contained values of the owner's choice instead of their actual values.
APIs and a clear user interface for the override mechanism could be specified by an appropriate TCG committee. Only the platform owner should be able to do this; whenever a machine provides an inaccurate attestation, it does so for what its owner considered an appropriate reason. This change would do nothing to undermine the basic security benefits of the TCPA hardware, including those outlined in the Safford article; you still could tell whether your computer had been altered.
(via Vitanuova)
