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  • From: Seth Alan Woolley <seth AT positivism.org>
  • To: Eric Sandall <eric AT sandall.us>
  • Cc: sm-discuss AT lists.ibiblio.org
  • Subject: Re: [SM-Discuss] verifying gpg keys
  • Date: Wed, 10 Aug 2005 23:03:49 -0700

On Wed, Aug 10, 2005 at 10:37:14PM -0700, Eric Sandall wrote:
> On Thu, 11 Aug 2005, Jeremy Blosser (emrys) wrote:
> > [0] https://lists.ibiblio.org/sympa/arc/sm-discuss/2005-April/010332.html
> > --
> > Seth does note in here that "SOURCE_GPG will be preferred" over
> > SOURCE_HASH, but doesn't say why; I'd assume he means it's preferred
> > because it provides better verification when appropriate key/source
> > verification has been done to back it up.
>
> IIRC GPG's hash algorithm is better than md5sum, sha1, etc. and can
> easily be 'modified' if a hole/issue is found.

Just want to emphasize, we do not use PGP's hash algorithms directly --
it's one component of how PGP is used, however, most of the time sha1 is
used, which is a bit stronger than md5 at this point.

Secondly, I preferred SOURCE_GPG over SOURCE_HASH to the extent that if
both methods are available to the spell writer, that they should select
SOURCE_GPG as the method because it completes the integrity chain back
to the original author (which can go further, but our responsibility is
to get it at least back to the original author). Once the key is added,
each update carries with it further guarantees of trust -- a MIM
security attack on older, more used keypair chains is more and more
difficult even without initial verification. With HASHes we tend to not
get it from a source which has an increasing level of security -- each
new hash is received under similar MIM vulnerable circumstances.

If the hash were gpg signed, though, this concern wouldn't be there,
however, GPG is still more preferred than the HASH in a non-security
sense since spell updates require even less effort on each subsequent
update.

And moreover, the ability to rely on gnupg to update hashes used in PGP
helps future proof the API.

Since we publish the keys we use to verify the sources the paranoid even
have the ability to self-check our verification, which makes us a very
unlikely target for somebody trying to use us as a vector for attack.
They'd be exposed pretty darn quick unless they could attack both us
(and every other gpg publishing distro) and the download site at the
same time. This element of peer review gives us extra protection.

Incorrect hashes though tend to be "oh that's a mistake" or "oh we
updated that tarball". When this happens in a PGP system, you've got a
more serious problem than a mistake most of the time.

So having said that, yes, we should be diligent to check our public keys
just because of the nature of not wanting to have to do a brown-bag
update of a vendor pgp key, but it is designed to have some amount of
self-protection built into it. I'm aware of no other distro with an
implementation this well-designed (ok, well, I lead design of it, so I'm
biased ;)).

One possible way to make it easy for gurus is to not have gurus do the
checking. They can do very basic checks enough to satisfy themselves
and commit to devel grimoire with a WIP, at which point it should never
hit test until a separate key review committee can approve it. This
could be composed of trusted members of the community that don't need to
be coders themselves. Maybe they have extensive PGP experience and can
follow the steps necessary to verify a public key, including phone
calls, email lists, person-to-person contact, following a standard
agreed upon and interpreted by members of the specific committee.

This puts the pressure off of coders who might not have the time to
worry about such measures, and yes, they should update our wiki with all
the methods used to validate each key.

--
Seth Alan Woolley [seth at positivism.org], SPAM/UCE is unauthorized
Quality Assurance Team Leader & Security Team: Source Mage GNU/linux
Linux so advanced, it may as well be magic http://www.sourcemage.org
Secretary Pacific Green Party of Oregon http://www.pacificgreens.org
Key id FDCEE733 = 5302 B414 64C4 6112 3454 E082 99F0 69DC FDCE E733

Attachment: pgpuN1v3bOTWj.pgp
Description: PGP signature




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