Joey Hess <[EMAIL PROTECTED]> wrote: > Goswin von Brederlow wrote: > > What can we do with deb signatures? > > > > For our current problem, the integrity of the debian archive being > > questioned, the procedure would be easy and available to every user: > > > > 1. get any clean Debian keyring (or just the key signing the keyring) > > 2. verify the latest Debian keyring > > 3. verify that each deb was signed by a DD and the signature fits > > The canoical attack against signed debs in this situation is to find a > signed deb on snapshot.debian.net that contains a known security hole. > Now inject it into the compromised archive, with a changed filename, and > edit the Packages file to have its md5sum. Now a user's checks will > succeed -- the package is signed with a developer's key -- but they will > install the old, insecure .deb. The only hint will be a warning from > dpkg that it is downgrading the package, and a clever attacker might > avoid even that.
We could use a revocation list where signatures of packages with known security holes are listed as being revoked. Of course, you'd need to be online to check it when installing/updating packages. And the revocation list would best be served from a server that's secure and separate from the archive servers to make attacks against it a bit more difficult. > I would still like to be able to produce signed debs, it's another layer > of security, but they are no panacea. True.
