In the past few weeks new information has come out on the Trusted Computing (TC) front which provides clues to where this powerful and controversial technology may be heading. Much of this has come from Intel, which has revealed more information about their LaGrande technology, now un-codenamed to Trusted Execution Technology. A good source of links is the Hack the Planet blog, http://wmf.editthispage.com/ - scroll down to the September 25 entry. LaGrande was originally designed as the hardware support for Microsoft's now-defunct Palladium, relating to the differences between Palladium and TCPA (now called TCG). Both technologies relied on the TPM chip to take measurements of running software, report those measurements remotely via trusted attestations, and lock encrypted data to those measurements so that other software configurations could not decrypt it. These are the core capabilities which give TC its power. But there were important differences in the two approaches. TCPA was focused on a measured boot process. As the system boots, each stage would measure (i.e. hash into the TPM) the next stage before switching control to it. At the end of this process the TPM's Platform Configuration Registers would hold a "fingerprint" of the software configuration that had booted. With a TPM-aware OS the PCRs could be further updated as each program launches to keep an up-to-date picture of what is running. Palladium instead wanted to be able to switch to "trusted" mode in mid stream, after booting; and wanted to continue to run the legacy OS while new applications ran in the trusted area. LaGrande Technology (LT, now TET), in conjunction with new TPM capabilities offered in the 1.2 chips now available, would provide the support for this "late launch" concept. Palladium is now gone but Intel has continued to develop LaGrande and has now released documentation on how it will work, at http://www.intel.com/technology/security/. Late launch starts with the OS or the BIOS executing one of the new LT instructions. This triggers a complex sequence of operations whose purpose is to load, measure (ie hash into the TPM) and launch a hypervisor, that is, a Virtual Machine Monitor (VMM). The hypervisor can then repackage the state of the launching OS as a Virtual Machine (VM) and transfer control back to it. The OS has now become transparently virtualized and is running on top of the VMM. The VMM can then launch secure VMs which execute without being molested by the legacy OS. Another enhancement of LT is that the chipset can be programmed to prevent DMA access to specified memory areas. This will close a loophole in existing VMM systems, that VMs can program DMA devices to overwrite other VMs' memory. This protection is necessary for the TC goal of protected execution environments. Both VMWare and Xen are getting involved with this technology. As the blog entry above says, Intel donated code to Xen a few days ago to support much of this functionality, so that Xen will be able to launch in this way on TET machines. Another link from the blog entry is an amazing Intel presentation showing how excited the NSA is about this technology. Within a couple of years they will be able to acquire Commercial Off the Shelf (COTS) systems configured like this, that will allow running multiple instances of OS's with different security classifications. The slides show a system running two versions of Windows, one for Secret and one for Top Secret data, appearing in separate windows on the screen. Xen or VMWare with TET will be able to do this very soon if not already. Here's Intel's description of how software might be configured to use this capability, from their "Trusted Execution Technology Architectural Overview" linked from the LaGrande page above:

Trusted Execution Technology provides a set of capabilities that can be utilized in many different operating environments (Figure 2). One proposed architecture provides a protection model similar to the following:

A standard partition that provides an execution environment that is identical to today's IA-32 environment. In this environment, users will be able to run applications and other software just as they do on today's PC. The standard partition's obvious advantage is that it preserves the value of the existing code base (i.e. existing software does not need modification to run in the standard partition) and potential future software that is less security conscious. Unfortunately, it also retains the inherent vulnerabilities of today's environment.

A protected partition provides a parallel and co-existing environment that will run hardened software that makes use of the hardware-based security foundation enabled by Trusted Execution Technology. Within this environment, different applications can run in isolation, free from being observed or compromised by software running in the standard partition and other applications running in the protected partition. A protected partition requires a Trusted Execution-capable processor, chipset, and a domain manager to provide domain separation. The TPM device protects secrets stored in a Trusted Execution platform when the protected partition is not running. The Trusted Execution Technology protection model can support any domain manager, and future, enhanced OS kernel.

Applications can be written to execute within the protected partition or, in most cases, make use of both partitions. In the latter case, much of the application code could still reside within the standard partition (this code manages the human interface and handles I/0) and services written to manipulate secure or sensitive information, would move to modules written for the protected partition.

To anyone who studied what was known as Palladium, this will sound strangely familiar. It is exactly how Microsoft described their system, with the legacy side and the secure side, and applications that would somehow straddle the two. So we see, with Intel's release of LaGrande (4Q06), Palladium is back. And this time, it's Xen! Xen is already enhanced to virtualize the TPM chip, and has further plans to add capabilities to measure VMs as they load and execute. TET will only improve this functionality and allow for full Palladium capabilities in the near future. It's ironic that opponents of TC frequently claimed that one of its goals was to destroy open source software, when here today we see that it is in the open source world that TC is thriving. Xen has support for it, the 2.6 Linux kernel has built-in TPM drivers, the trousers.sf.net project provides a robust Trusted Software Stack implementation for TPM access, and numerous research projects have investigated adding other TPM hooks within the Linux kernel. See also the recent controversy over Linus Torvalds' break with the FSF over their efforts to put anti-TC clauses into the new GPLv3. Now it appears that all the capabilities of Palladium, the technology people thought was going to be so evil, will be present in the friendly face of Linux and Xen. Maybe this will finally cause the unwashed masses to stop believing the easy lies which have been fed to them for so long about the nature of TC, and look a little deeper at a technology with great power and potential.