The Microsoft Secure PC: MS patents a lock-down OS
Denial of Sharing attack
Remember the Microsoft Research Project for a "Secure PC" that we told you about in March?
A formal patent claim for a "digital rights management" - i.e. share denial OS - was granted on Wednesday and has surfaced, via the Cryptome web site.
The authors include Secure PC team leader Paul England and distinguished Xerox PARC veteran Butler Lampson, who as well as working on the design of Ethernet and the Alto, has a long history in studying trusted systems, and the application was filed in January 1999.
It's very simple. The patent application seeks to protect "a computerized method for a digital rights management operating system comprising: assuming a trusted identity; executing a trusted application; loading rights-managed data into memory for access by the trusted application; and protecting the rights-managed data from access by an untrusted program while the trusted application is executing."
And that's it. However the designers have thought of many circumvention tactics likely to be thrown at what they call a "DRMOS", and the patent lists methods of secure access to the page file, of ejecting untrusted applications off the system, and resetting the system clock against a trusted server. The filing also pays attention to the practical difficulties of publishers maintaining huge databases of their consumers' PCs.
"the content provider would have to maintain a registry of each subscriber's DRMOS identity or delegate that function to a trusted third party," and the number of unique DRMOSes, the authors acknowledge, could run into the millions.
It represents a work in progress, as regular readers will know. There's no attempt to cloud its intentions behind a smokescreen of law enforcement or national security - although the Secure PC is an advance on current standards. No, it's designed to prevent the "Piracy of digital content, especially online digital content.
"In a very real sense, the legitimate user of a computer can be an adversary of the data or content provider. 'Digital rights management' is therefore fast becoming a central requirement if online commerce is to continue its rapid growth," according to the patent.
"Content providers and the computer industry must quickly provide technologies and protocols for ensuring that digital content is properly handled in accordance with the rights granted by the publisher. If measures are not taken, traditional content providers may be put out of business by widespread theft, or, more likely, will refuse altogether to deliver content online."
The DRMOS relies on a secure boot sequence and an identifier in the CPU, the latter being the subject of an earlier filing. But that's not all, quite possibly: if the PC configuration is changed, "a plug-and-play DRMOS must then 'renounce' its trusted identity and terminate any executing trusted applications... before loading the component. The determination that an untrusted component must be loaded can be based on a system configuration parameter or on instructions from the user of the computer."
The patent doesn't specify how keys should be generated, or where they should be stored, and kicks around a few suggestions. At which point in the filing, the enormity of the challenge of creating a DRMOS should be evident: it's a mammoth task.
But perhaps not as great as the political and social challenge as selling such a proposition to consumers. Microsoft may be a convicted monopolist, but that doesn't make the task any easier. This particular DRMOS architecture doesn't specify any kind of DRM, and when the technology vendors do agree on a magic bullet for copy protection, as they did with opening the door to build CPRM into fixed storage, they found a ready and immediate public backlash. (CPRM has succeeded on its original goal of removable media, with the SD card).
In any case, the amount of privately generated content (home videos, spreadsheets) which could fall foul of a DRMOS, and the amount of existing, unsecured freely shared media (MP3s) also presents an obstacle to consumer acceptance.
However the precedent of Microsoft's introduction of its own Windows Product Activation could be viewed as a dry run. It was introduced with fairly strict requirements for how much of a PC's configuration could change, and was gradually loosened. But it's here. ®