Re: SHA1 collisions found

On Fri, Feb 24, 2017 at 5:21 PM, Jeff King [off-list ref] wrote:

On Fri, Feb 24, 2017 at 05:00:55PM -0800, David Lang wrote:

quoted

On Fri, 24 Feb 2017, Jeff King wrote:

quoted

So I'd much rather see strong rules like:

 1. Once a repo has flag-day switched over to the new hash format[1],
    new references are _always_ done with the new hash. Even ones that
    point to pre-flag-day objects!

how do you define when a repo has "switched over" to the new format in a
distributed environment?

You don't. It's a decision for each local repo, but the rules push
everybody towards upgrading (because you forbid them pulling from or
pushing to people who have upgraded).

So in practice, some centralized distribution point switches, and then
it floods out from there.

This seems like the most reasonable strategy so far. I think that
trying to allow long term co-existence is a huge pain that discourages
switching, when we actually want to encourage everyone to switch
someone has switched.

I don't think it's sane to try and allow simultaneous use of both
hashes, since that creates a lot of headaches and discourages
transition somewhat.

Thanks,
Jake