Re: Hash algorithm analysis
On Sat, 21 Jul 2018 23:59:41 +0000, brian m. carlson wrote:
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> On Sun, Jul 22, 2018 at 12:38:41AM +0200, Johannes Schindelin wrote:
> > Do you really want to value contributors' opinion more than
> > cryptographers'? I mean, that's exactly what got us into this hard-coded
> > SHA-1 mess in the first place.
>
> I agree (believe me, of all people, I agree) that hard-coding SHA-1 was
> a bad choice in retrospect. But I've solicited contributors' opinions
> because the Git Project needs to make a decision *for this project*
> about the algorithm we're going to use going forward.
>
> > And to set the record straight: I do not have a strong preference of the
> > hash algorithm. But cryprographers I have the incredible luck to have
> > access to, by virtue of being a colleague, did mention their preference.
>
> I don't know your colleagues, and they haven't commented here. One
> person that has commented here is Adam Langley. It is my impression
> (and anyone is free to correct me if I'm incorrect) that he is indeed a
> cryptographer. To quote him[0]:
>
> I think this group can safely assume that SHA-256, SHA-512, BLAKE2,
> K12, etc are all secure to the extent that I don't believe that making
> comparisons between them on that axis is meaningful. Thus I think the
> question is primarily concerned with performance and implementation
> availability.
>
> […]
>
> So, overall, none of these choices should obviously be excluded. The
> considerations at this point are not cryptographic and the tradeoff
> between implementation ease and performance is one that the git
> community would have to make.
Am I completely out of the game, or the statement that
"the considerations at this point are not cryptographic"
is just the wrongest ? I mean, if that was true, would we not be sticking to SHA1 ?
Show 31 quoted lines
> I'm aware that cryptographers tend to prefer algorithms that have been
> studied longer over ones that have been studied less. They also prefer
> algorithms built in the open to ones developed behind closed doors.
>
> SHA-256 has the benefit that it has been studied for a long time, but it
> was also designed in secret by the NSA. SHA3-256 was created with
> significant study in the open, but is not as mature. BLAKE2b has been
> incorporated into standards like Argon2, but has been weakened slightly
> for performance.
>
> I'm not sure that there's a really obvious choice here.
>
> I'm at the point where to continue the work that I'm doing, I need to
> make a decision. I'm happy to follow the consensus if there is one, but
> it does not appear that there is.
>
> I will admit that I don't love making this decision by myself, because
> right now, whatever I pick, somebody is going to be unhappy. I want to
> state, unambiguously, that I'm trying to make a decision that is in the
> interests of the Git Project, the community, and our users.
>
> I'm happy to wait a few more days to see if a consensus develops; if so,
> I'll follow it. If we haven't come to one by, say, Wednesday, I'll make
> a decision and write my patches accordingly. The community is free, as
> always, to reject my patches if taking them is not in the interest of
> the project.
>
> [0] https://public-inbox.org/git/CAL9PXLzhPyE+geUdcLmd=pidT5P8eFEBbSgX_dS88knz2q_LSw@mail.gmail.com/
> --
> brian m. carlson: Houston, Texas, US
> OpenPGP: https://keybase.io/bk2204
--
Eric Deplagne