Re: Integrity checking NANOBSD images



Poul-Henning Kamp wrote:
In message <44B4010E.7010809@xxxxxxx>, 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.

That suggestion is a very good point, although trying to find a single trojaned image which matches several checksum methods is supposed to be a highly difficult task.

--
-Chuck

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