At 04:05 PM 11/07/2006, Poul-Henning Kamp wrote:
In message <[EMAIL PROTECTED]>, Chuck Swiger writes:
>Checksumming the device image is a fine way of checking the
integrity of it,
>assuming it is read-only. The only thing you might want to do is
use two or
>three checksum algorithms (ie, use sha256 and md5 and something
else), so that
>someone can't create a new image which matches the sha256 checksum of the
>original.
A much better idea is to send a random "salt" to be prepended to
the disk image before it is run through sha256, that would prevent
the attacker from running sha256 and any other algorithm you
could care for on the image, store the results and return them
with trojans.
Copying the sha256 binary over is no guarantee against a kernel
embedded trojan.
But then again, how paranoid one has to be is a matter of preference.
Hi,
Thanks for the responses. I know there are no perfect ways.
I guess I want to understand the risk as much as possible and
mitigate against tampering as much as possible without designing the
requirement for some guy to sit in front of the box with a gun :)
With respect to prepending a random salt to the image, can you expand
what you mean ?
---Mike
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
[EMAIL PROTECTED] | 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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