Public SourceMage Discussion List

[Andrew Stitt <afrayedknot AT thefrayedknot.armory.com>]

On Wed, Nov 01, 2006 at 05:41:06PM -0600, David Kowis wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> 
> Finally, a bit off topic, our grimoire verification keys are within the
> very grimoire we're attempting to verify. We've got a small chicken-egg
> problem there. Perhaps we could seperate the gpg keys into their own
> grimoire? That is the simplest solution I've come up with, but I'm not
> sure if it's the most elegant.
> 

The chicken and egg problem is actually un-avoidable. If you put the
keys in a side location or grimoire how does the user verify they got
the right ones? You need a key. How do you securely update that key?

In the current scheme to add a new key you bootstrap it with existing
ones. (I'll outline where the first key came from below.)

This may seem inconvenient but it has some nice properties.
Mainly that key compromise isn't the weakest link. Nor does the scheme
add any vulnerabilities that don't already exist.

An attacker would want to compromise our keyrings so they could sign
and distribute grimoires containing malicious code. In this case
compromise keyrings mean get them on the user's box. The only way to get
a new key out to users is to put it in the smgl-pubkeys spell.

The only ways to do that are:
1) have push access to our scm
2) break into the machine used for signing

Both of those risks exist without gpg verification. And in both of
those scenarios the attacker wouldn't need to compromise the grimoire
signing keys. They could simply put their malicious code directly in
the grimoire since they already have "root" so-to-speak.

Also, the current scheme is simple for users and has minimal code
complexity. New key distribution happens automatically when the user
downloads and updates. No new code is required for that. The grimoire
they download is verified by a key they already have.

The first key came with the installed system from the iso. In theory the
user verified the checksum or signature on the iso before using it. The
iso creator in theory verified the grimoire they put on the iso. If I
recall correctly this falls all the way back to a signed email from Seth
containing the original verification keys.

So, the original vision for adding a new key involved an existing
signer signing a grimoire containing an updated smgl-pubkeys spell. Then
subsequent grimoire tarballs could be signed by the new signer.

-Andrew


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| Andrew D. Stitt  | acedit at armory.com    | astitt at sourcemage.org | 
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