Integrity checking NANOBSD images
Chuck Swiger
cswiger at mac.com
Tue Jul 11 19:50:57 UTC 2006
Mike Tancsa wrote:
[ ... ]
> # ssh remote1.example.com "/tmp/rand-directory/dd if=/dev/ad2s1a
> bs=4096k | /tmp/rand-directory/sha256"
> 120+1 records in
> 120+1 records out
> 505389056 bytes transferred in 169.727727 secs (2977646 bytes/sec)
> 955ebad583bfc0718eb28ac89563941407294d5c61a0c0f35e3773f029cc0685
>
> Can I be reasonably certain the image has not been tampered with ? Or
> are there trivial ways to defeat this check ?
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.
--
-Chuck
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