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From: Florian Weimer <fw@deneb.enyo.de>
To: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Chris Friesen <chris.friesen@genband.com>,
        Greg KH <gregkh@linuxfoundation.org>,
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Subject: Re: [GIT PULL] Load keys from signed PE binaries
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Date: Thu, 28 Feb 2013 20:41:13 +0100
In-Reply-To: <20130228193023.GA8090@srcf.ucam.org> (Matthew Garrett's message
	of "Thu, 28 Feb 2013 19:30:23 +0000")
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* Matthew Garrett:

>> Would it be possible to have a signed bootloader that allows booting
>> Win8 from within the secure environment, or it could exit the secure
>> environment and run unsigned grub?
>
> What would stop the unsigned grub from installing a firmware hook that 
> lies about whether or not Secure Boot is enabled, and then booting 
> Windows?

Windows would not have access to the product key because it is stored
in a variable without EFI_VARIABLE_RUNTIME_ACCESS, so WGA and other
checks will fail, and the user will notice.

(Not sure if it is implemented this way, my test machine lost the
firmware-embedded product key after the mainboard was replaced.)