Re: [gentoo-dev] git security (SHA-1)

[Ian Stakenvicius]

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On 15/09/14 07:59 PM, Rich Freeman wrote:
> On Mon, Sep 15, 2014 at 6:11 PM, Gordon Pettey
> <petteyg359@×××××.com> wrote:
>>
>> Even if you wanted to burn the money to find that magical
>> collision that actually contains working code, you've still got
>> to somehow propagate that to other repositories, since they'll
>> just ignore it for having the same hash as an already-existing
>> object.
>>
>
> Well, if you're willing to trust that nobody is able to tamper
> with repositories, then you don't need gpg signatures in the first
> place.
>
> I think that gpg signatures protected by an SHA1 hash provide
> fairly little security - a chain is as strong as its weakest link
> and sha1 has been considered fairly weak for years now.
>
> However, I think it does make sense to at least get gpg into the
> workflow in the hopes that some day git will move to a stronger
> hash, and since it isn't a huge hardship to do so.
>
> I wouldn't make too light of the use of SHA1 though.  As you point
> out simply exploiting it isn't enough, but the whole reason for
> having signatures is to make an attack on a central repository
> useless. Having gpg on top of ssh keys and all that is obviously
> redundant, but that is the whole point of it.
>
> -- Rich
>

If the issue preventing protection is that the gpg signature only
signs the hash, couldn't we just make repoman automatically add to the
bottom of the comment a clearsign on the contents of the commit?


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