From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with archive (Exim 4.43) id 1Laf0B-0000GR-1A for mharc-grub-devel@gnu.org; Fri, 20 Feb 2009 18:41:51 -0500 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Laf09-0000GM-AO for grub-devel@gnu.org; Fri, 20 Feb 2009 18:41:49 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Laf08-0000GA-Ny for grub-devel@gnu.org; Fri, 20 Feb 2009 18:41:49 -0500 Received: from [199.232.76.173] (port=38651 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Laf08-0000G7-Kw for grub-devel@gnu.org; Fri, 20 Feb 2009 18:41:48 -0500 Received: from fg-out-1718.google.com ([72.14.220.158]:3055) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1Laf08-0000L4-5a for grub-devel@gnu.org; Fri, 20 Feb 2009 18:41:48 -0500 Received: by fg-out-1718.google.com with SMTP id l27so1561589fgb.30 for ; Fri, 20 Feb 2009 15:41:46 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:date:from :user-agent:mime-version:to:subject:references:in-reply-to :content-type:content-transfer-encoding; bh=VekKDGUAtjZYSS9Z8ak/ybyANeerq21iyuWpf2xoKf4=; b=BBlnkX6O5MmfJuAwXWMrlbbGY/X9hodihdZl6dzbswW05I1tvTbjZLZQ3GH/kHCiSP vqQgdVNYlFFKb94ZmwU7bmWhQ2ejAnVhn2R3oWulXpK+lLvMXuhcrdivTbnNfZjnSOC8 DX0y2UTWoxkwsFU5E+15enL2bk4ROi2wfuOaA= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:subject:references :in-reply-to:content-type:content-transfer-encoding; b=NO/wBd9yU59qQBe9+0uGS2WVNBMzxwl8fKm1c0JO54IiGvjcDtJmox+3uMX1OSfRy5 kx0VutgUVWQkPkDeoz9Vj2yEeqjPvscQ/p0fxaeh/3xRpQO9egTIMZWSOVZV4tJssBDT 3MXvhMIsK4DcMGETTAgDYqBAnD/7T9xjTa+OI= Received: by 10.86.65.9 with SMTP id n9mr1363034fga.55.1235173306786; Fri, 20 Feb 2009 15:41:46 -0800 (PST) Received: from ?192.168.1.25? (184-134.62-81.cust.bluewin.ch [81.62.134.184]) by mx.google.com with ESMTPS id 4sm615273fge.54.2009.02.20.15.41.45 (version=SSLv3 cipher=RC4-MD5); Fri, 20 Feb 2009 15:41:46 -0800 (PST) Message-ID: <499F3FB9.9070304@gmail.com> Date: Sat, 21 Feb 2009 00:41:45 +0100 From: phcoder User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: The development of GRUB 2 References: <499F25B0.8000202@gmail.com> <499F376C.60906@student.ethz.ch> In-Reply-To: <499F376C.60906@student.ethz.ch> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-detected-operating-system: by monty-python.gnu.org: GNU/Linux 2.6 (newer, 2) Subject: Re: SHA-1 MBR X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: The development of GRUB 2 List-Id: The development of GRUB 2 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 20 Feb 2009 23:41:49 -0000 Hello Jan Alsenz wrote: > Hi! > > Wow, cool work! Thanks > It's not complete SHA-1, but the rest should be just a constant offset. I already said how it differs from standard one. If you feed padded byteswapped data to it and then byteswap the rsult back you obtain exactly normal SHA-1. But as I said if size is fixed it's compeletely equivalent in security to normal SHA-1 (you can easily prove formally that any successful attack on one variant immediately results in successful attack on another variant) > > But I'm still not sure, what you are trying to do here, is the MBR your root of > trust? I'm trying to achieve universal verification scheme which is able to do what is needed to support tpm ("prolonging chain of trust" in tpm unstandard parlance) without using tpm itself. Such scheme can in future be useful in other applications as well. > If not, who checks the MBR? This can't be done by grub because it happens before any part of grub is loaded. to verify grub you need to rely on vendor/platform-specific mechanisms. I personally find "tpm without tpm" more attractive because it can be easily reused on another platform or any alternative to tpm (perhaps anybody here or coreboot folks will come up with something). Additionally it workarounds many bios and tpm bugs. I will continue working on sha-1 boot. My goal is to load core.img checked. After that point there is much more space and any signature based solution can be used. > > Greets, > > Jan > Regards Vladimir 'phcoder' Serbinenko