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On Fri, 2006-05-19 at 10:46 +0100, Chris Bainbridge wrote: |
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> The only attack most people really care about is a compromised rsync |
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> server. There is no practical way to protect against the other attacks |
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> - and at the end of the day, if a developer gets compromised it |
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> doesn't matter whether it's a gpg key or ssh key, the effect is the |
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> same. |
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The difference is how you handle any problems. You can't avoid it, but |
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you can reduce the impact. |
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> The discussion about which files to sign is pointless - the extra |
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> computational cost of signing all files in the tree is insignificant, |
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> and how are we supposed to know how future tools will handle things |
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> like the licenses? Just do it properly now and sign every file. |
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In theory yes. |
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Practically you have to find a non-intrusive way so signatures are per |
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file. |
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There are potential problems with "special" files like package.mask that |
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will be modified often by different people ... signing that is a bit |
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silly |
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> We already trust the master cvs server admins (and they could just |
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> replace the whole tree anyway), so what benefit does a distributed |
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> signing system like gpg actually give to the developers or users? I |
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> can't see any that are worth the costs of key management (and there |
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> are costs, otherwise a system would've been put into place years |
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> ago). |
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No central authority --> no single point of failure |
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Give me a central server and I will focus on hacking that ... hacking 50 |
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developers is much harder ;-) |
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> So my simple proposal would be to use a single key, and a post-commit |
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> cvs hook to sign the whole tree. It takes me 1.5 seconds with gnupg to |
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> generate a signature covering the whole tree on my desktop here. I |
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> don't know how many commits per day there are (and maybe that would be |
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> reduced with an atomic commit system like svn), so I don't know if |
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> this is an acceptable cost. I think it probably is, but if not, then |
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> signing could be done per-directory. |
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I don't see what that gains you ... what exactly does this signature |
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express? |
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and 1.5sec doesn't appear realistic to me, I'd expect it to take ~1 |
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minute even on a fast system |
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> The benefits of this would be that changes are minimised - developers |
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> and users act the same, the impact on the tree is a 191 byte |
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> signature, and yet it will protect against the most likely and most |
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> practical form of attack. |
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So ... DoS scenario |
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I just add one byte to the tree and the signature fails ... what then? |
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> I was much more pro-distributed trust system in 2003 (or whenever this |
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> was last discussed), but I think the right solution now is the |
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> practical, easy to implement one. |
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I think I'd prefer a hybrid. |
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One possibillity would be: |
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- every dev signs as it is done now |
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- post commit an automated signature from a master key is added |
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so the normal user can check the master signature, and the paranoid |
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people can use the per-dev keys. |
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Where I fully agree is "practical" and "low impact" - it should be easy |
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to use so that everyone can use it without lots of configuring. This of |
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course limits the complexity that we can allow. |
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wkr, |
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Patrick |
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-- |
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Stand still, and let the rest of the universe move |
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