[Mageia-dev] PGP keys and package signing
boklm at mars-attacks.org
Mon Jan 31 04:16:43 CET 2011
Now that we have a working build system, we need to setup the last part,
which is package signing. And for this we need a GPG key. So it's time
to decide on some policy about PGP keys.
We can look at how it was done at Mandriva. If I remember correctly :
- cooker packages were signed with a key stored on the build system
- stable release packages were signed at release time with an other
key, not stored on the build system, but stored on the server used
to prepare the release and generate the ISOs
- updates for main repository were managed by secteam, and signed by
secteam key. The secteam didn't use the build system but their own
servers, so the key was stored on their servers
- updates for contrib repository were signed using a key stored on the
- backports for main and contrib repository were signed using a key
stored on the build system
However there are a few problems with this :
- too many different keys, with different names, it's difficult to see
which ones are really official.
- keys stored on the build system were not secure (all contributors and
apprentice had shell access on the build system and could easily become
root using iurt or other techniques, and then access the secret keys).
We won't provide shell access on the same servers as the build system
so it should be more secure, however it is always possible that a
server be compromised, with all the pgp keys on it, so we should plan
for it, and be able to revoke keys if it happens
- using a different key for developement version, and released version
means we need to resign all packages for the release, taking a lot
of time, cpu, and bandwidth to copy the packages between different
- updates will be done using the same build system, so there is no use
to have two different keys for release and updates packages
- signed packages are supposed to prevent someone from modifying
packages on the mirrors. However the public key used to verify the
packages is downloaded from the mirror, and could be modified too.
So it would be very easy to create a fake mirror with modified
packages. We should fix that by allowing only trusted keys to be used.
So I propose that we use two keys :
- We sign all packages from all repositories using only one key. This
key is stored on the buildsystem. We can call it packages at mageia.org.
- We have an other key, that we call board at mageia.org. This key is
not used on any online server, and is supposed to never be changed,
and should not be compromised. Only a few people have a copy of this
key (some people from board ?), kept on a usb key hidden somewhere, but
not on their laptop or any computer with internet connection. This key
is used to sign the key packages at mageia.org (and revoke it if needed),
and other official keys of the project, but never used for anything
else (not for receiving encrypted messages). And the signature is
sent on public keyservers.
- We add the board at mageia.org public key inside the urpmi package.
We change urpmi so that it refuses to use any key which has not been
signed by board at mageia.org. And urpmi should frequently update the
keys it is using from public keyservers to check that its signature
from board@ has not been revoked (or that the key self signature has
not been revoked).
- In case we think the packages@ key may have been compromised, or is
too old, or we want to change it for any other reason, we revoke the
key, and/or revoke the signature from board@ so that it is no
longer accepted by urpmi. We create a new key, we sign it with
the board@ key and we can start to use this new key.
According to this page :
there is also a few things we need to improve in urpmi to make it more
secure (signed hdlists, and expiration dates on hdlists), but this is
In this thread :
misc proposed that we publish tarballs of our software on the mirrors,
and sign them using a pgp key. So we need a key for that. We also want
to sign ISOs, maybe with a different key. So I think we can do the same
as for packages key, we create new keys for software releases and for
ISOs, and we sign those keys with the board@ key. And we can tell
everybody that all files released by the project are always signed by
a key that was signed by the board@ key.
If we decide to do this, someone from board could generate the key next
week at fosdem after the election, save it on usb key for other board
members, and give the fingerprint to everybody to sign the key.
Any opinions on this ? Or other ideas ? Or comments ?
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