Date: Tue, 11 Jul 2006 20:22:23 +0000 From: "Poul-Henning Kamp" <phk@phk.freebsd.dk> To: Mike Tancsa <mike@sentex.net> Cc: freebsd-security@freebsd.org Subject: Re: Integrity checking NANOBSD images Message-ID: <77192.1152649343@critter.freebsd.dk> In-Reply-To: Your message of "Tue, 11 Jul 2006 16:18:19 -0400." <6.2.3.4.0.20060711161049.04bd37a0@64.7.153.2>
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In message <6.2.3.4.0.20060711161049.04bd37a0@64.7.153.2>, Mike Tancsa writes: >With respect to prepending a random salt to the image, can you expand >what you mean ? If you just run sha256 on the disk image, and the attacker finds out, he will just run sha256 himself and record the result. Arming a trojan to just do 'sleep 145 ; echo "sha256 = 0248482..."' when you thing you're running sha256 would be trivia. If you take a random hexstring of 16 digits and prepend to the disk-image, then the output of the sha256 is not constant and in order to simulate it, he has to have access to the disk image to feed into sha256 -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence.
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