Re: [gentoo-dev] Manifest signing

["Robin H. Johnson" <robbat2@gentoo.org>]

On Wed, Nov 02, 2011 at 01:03:21PM +0100, enno+gentoo@groeper-berlin.de wrote:
> I followed the threads about manifest signing with interest and even had
> a look at the manifest signing guide [4]. Sounds nice at first view.
> But, please correct me, if I'm wrong. I didn't find a place where these
> signatures are verified.
> Is manifest signing for the infrastructure team, enabling them to verify
> the author of a commit (see GLEP57 [1])? Wouldn't this be obsoleted by
> commit signing if the move to git is done ([2])?
Developer signing is radically altered in the face of git yes, that's
one of the reasons not much has happened there. But the other larger
reason is that developer signing pales in importance to the signature
chain between infra->user.

> If it is (also) for the users, why is there no code for it in portage
> anymore [3]?
Hmm, I hadn't see that removal, but it makes sense unless the entire
tree is developer-signed, which isn't likely to happen soon.

> Okay "why" is clear. Obviously nobody was maintaining it...
The code worked when I used it...

> I thought about signing the manifests of my overlay. But this is
> senseless, if there is no automatic check. I can't think of any user
> verifying manifest signatures by hand.
There's a chicken & egg problem with most signing. You need to
communicate the valid keys out of band from the actual repo.
Maybe the layman data is a good place for that, but until such a
location is figured out, you have zero security gain (if the 'correct'
keys are only listed in a file in the repo, any attacker just replaces
that when he puts his other content in).

> How does infrastructure team check, if a GPG key belongs to a developer?
> The Manifest signing guide [4] simply says "Upload the key to a
> keyserver". Everbody can upload a key to the public keyservers. An
> attacker, able to modify a signed Manifest, could simply create a new
> key on the developers name and use it to sign the modified manifest.
> Therefore it must be clear which key really belongs to a dev.
Developers specify in their LDAP data what keys are theirs, and this
gets exported here, amongst other places:
http://www.gentoo.org/proj/en/devrel/roll-call/userinfo.xml

There was a prototype keyserver at one point as well, and I can generate
new keyrings if needed based on the LDAP data.

> Furthermore the Tree-Signing-GLEPs [5] seem to be incomplete.
> This looks like the right place to continue work on Tree Signing.
Those were the draft copies, which were finalized into GLEP 57..61.
You are correct that there are two unfinished GLEPs in that directory:
02-developer-process-security
03-gnupg-policies-and-handling

Of those, 03 can probably be written at this point.
02 is going to change radically when git comes into play.


-- 
Robin Hugh Johnson
Gentoo Linux: Developer, Trustee & Infrastructure Lead
E-Mail     : robbat2@gentoo.org
GnuPG FP   : 11AC BA4F 4778 E3F6 E4ED  F38E B27B 944E 3488 4E85