Mailinglist Archive: opensuse-buildservice (140 mails)

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Re: [opensuse-buildservice] adding checksums to the buildinfo
  • From: Greg Freemyer <greg.freemyer@xxxxxxxxx>
  • Date: Tue, 17 Jul 2012 19:54:02 -0400
  • Message-id: <>
On Tue, Jul 17, 2012 at 11:52 AM, Pascal Bleser
<pascal.bleser@xxxxxxxxxxxx> wrote:

As long as it is very clear to everyone that MD5 hashes can be
manipulated (quite easily, actually), then it's fine, but just
don't confuse it for an authoritative source :)

But indeed, in this case, the X.509 of the HTTPS connection
already provides an authenticity verification (as long as those
are indeed verified, including on the hostname).

Pascal (or anyone),

Ignoring the X.509 certificate:

I find it much more troublesome that in most situations the hash comes
from the same source as the package/data file. In those situations it
is trivial to change the payload file, then just recalculate the hash
and update it in the metadata file/source.

Thus if the hash value itself can't be robustly trusted, there is no
reason to worry about collision attacks which require far more
resources than an attacker just updating the hash value to match his
altered/infected payload file.

My impression is that the proposed solution makes no effort to "sign"
the metadata, thus if a attacker is able to access the distribution
infrastructure to manipulate the payload, they could manipulate the

Thus, other than the X.509 cert I argue that the whole proposed
integrity mechanism as I understand it is broken from a authentication
perspective no matter what hash is used, MD5 or otherwise.

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