Microsoft has announced that if computer makers wish to distribute machines with the Windows 8 compatibility logo, they will have to implement a measure called “Secure Boot.” However, it is currently up for grabs whether this technology will live up to its name, or will instead earn the name Restricted Boot.
When done correctly, “Secure Boot” is designed to protect against malware by preventing computers from loading unauthorized binary programs when booting. In practice, this means that computers implementing it won’t boot unauthorized operating systems — including initially authorized systems that have been modified without being re-approved.
This could be a feature deserving of the name, as long as the user is able to authorize the programs she wants to use, so she can run free software written and modified by herself or people she trusts. However, we are concerned that Microsoft and hardware manufacturers will implement these boot restrictions in a way that will prevent users from booting anything other than Windows. In this case, a better name for the technology might be Restricted Boot, since such a requirement would be a disastrous restriction on computer users and not a security feature at all.
The potential Restricted Boot requirement comes as part of a specification called the Unified Extensible Firmware Interface (UEFI), which defines an interface between computer hardware and the software it runs. It is software that allows your computer to boot, and it is intended to replace the traditional BIOS. Most Lenovo, HP, and Dell computers ship with UEFI, and other manufacturers are not far behind. All Apple computers ship with EFI and components from UEFI. When booting, this software starts a chain which, using a public key cryptography-based authentication protocol, can check your operating system’s kernel and other components to make sure they have not been modified in unauthorized ways. If the components fail the check, then the computer won’t boot.
The threat is not the UEFI specification itself, but in how computer manufacturers choose to implement the boot restrictions. Depending on a manufacturer’s implementation, they could lock users out of their own computers, preventing them from ever booting into or installing a free software operating system.
It is essential that manufacturers get their implementation of UEFI right. To respect user freedom and truly protect user security, they must either provide users a way of disabling the boot restrictions, or provide a sure-fire way that allows the computer owner to install a free software operating system of her choice. Computer owners must not be required to seek external authorization to exercise their freedoms.
The alternative is frightening and unacceptable: users would have to go through complicated and risky measures to circumvent the restrictions; the popular trend of reviving old hardware with GNU/Linux would come to an end, causing more hardware to be tossed in landfills; and proprietary operating system companies would gain a giant advantage over the free software movement, because of their connections with manufacturers.
We will be monitoring developments in this area closely, and actively campaigning to make sure this important freedom is protected. Our first step is to demonstrate that people value this freedom, and will not purchase or recommend computers that attempt to restrict it.
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Learn more about Windows 8, UEFI, and boot restrictions
- English Wikipedia UEFI overview
- UEFI Specifications
- White Paper: Secure Boot impact on Linux, a joint publication between Red Hat & Canonical.
News and Blogs
- UEFI secure booting, by Matthew Garrett; in addition to providing a brief overview of Restricted Boot, this article explains specifically why dual-booting an operating system may be difficult, or at times virtually impossible, for systems implementing and using Restricted Boot.
- Trusted Computing 2.0, by Ross Anderson of the Security Research, Computer Laboratory, University of Cambridge.
- Protecting the pre-OS environment with UEFI,Tony Mangefeste of Microsoft — a response to Garrett, et al.
- UEFI secure booting (part 2), by Matthew Garrett — a follow-up to Microsoft’s blog post.
- ArsTechnica article
- Supporting UEFI secure boot on Linux: the details, by Matthew Garrett
- On November 2, 2011, ZDNet blogger, Ed Bott, reports:
- A Dell spokesperson stated that, “Dell has plans to make SecureBoot an enable/disable option in BIOS setup.”
- HP has only stated that, “HP will continue to offer its customers a choice of operating systems. We are working with industry partners to evaluate the options that will best serve our customers.”