Thread

Git 3.0's upcoming SHA-256 default will be a costly mistake

570 points · 536 comments · chmaynard

gandreani · 1790877958 · focus · HN ↗
One of my favorite fun facts about Fossil SCM (another source control by the devs of sqlite) is that they patched their use of SHA1 6 days after the shattered attack was published:
"Both Fossil and Git started out using only SHA1 hashes. But when the SHAttered attack against SHA1 was published on 2017-02-23, the need to migrate to a stronger hash algorithm was recognized. Fossil added the ability to use SHA3-256 as an alternative on 2017-03-01 (six days after the SHAttered attack was first published). SHA3-256 is now the default for all new repositories and check-ins in Fossil, though older check-ins that occurred prior to SHAttered can still use their original SHA1 hash. Hence, no repositories had to be rebuilt and no hyperlinks were broken."
<a href="https://fossil-scm.org/home/doc/trunk/www/hundredandone.md" rel="nofollow">https://fossil-scm.org/home/doc/trunk/www/hundredandone.md
To me it's so interesting watching in realtime Git is still battling with this decision and for Fossil it was just another week of development.
That whole page is fun to read. Another fun fact somewhere else in the docs is that Fossil uses a grow-only set to store commits. They came up with this scheme some years before it was formalized by CRDTs!
1. fragmede · 1790878893 · focus · HN ↗
  It's easier to make world breaking changes when the world is really small. If git could magically just get everything and everyone to cut over and use git 3.0 in a magic instant, it wouldn't be having this problem.
  1. nofunsir · 1790880741 · focus · HN ↗
    Here's a stoichiometric bird for you:
    :%s/git 3\.0/python 3.0/g
    fragmede · 1790881784 · focus · HN ↗
    Or IPv6 or windows 11.
    :x
    Neovim's lazyvim plugin sucks because it takes over H C and L.
    Dylan16807 · 1790927984 · focus · HN ↗
    Huh wha? What problems are solved by getting all Windows users onto Windows 11 in particular?
    rovr138 · 1790937413 · focus · HN ↗
    Security since Windows 10 and below are not supported.
    <a href="https://support.microsoft.com/en-us/windows/deployment/updates-lifecycle/windows-10-support-has-ended-on-october-14-2025" rel="nofollow">https://support.microsoft.com/en-us/windows/deployment/updat...
    > Windows 10 support has ended on October 14, 2025
    Dylan16807 · 1790943103 · focus · HN ↗
    That's not true because of extended support, but even if it was true, what's the goal here? What benefit does the entire ecosystem share from getting people standardized on 11? Botnets get 25% smaller? That's not some kind of important threshold. Or developers can count on access to a newer mutex API or something? Whereas getting everyone on the same git hash or python or IP protocol streamlines things enormously.
    rovr138 · 1790953798 · focus · HN ↗
    > Whereas getting everyone on the same git hash or python or IP protocol streamlines things enormously.
    You don't think that if we had everyone on the same Windows version we could streamline things enormously?
    For MS, for developers, for hardware manufacturers, and so on to be able to deploy, for example, ipv6 since everyone is on the same stack? Same stack, same bugs, same fixes.
    Dylan16807 · 1790961843 · focus · HN ↗
    Microsoft can already put out an update to both windows 10 and 11 at the same time. They occasionally do this for bugfixes. That hits basically all Windows users.
    The difference in effort between updating one versus two very similar code bases is minor, especially when "Windows 10" and "Windows 11" each refer to multiple versions already.
    For drivers you only need one version to support both.
    IPv6 has been built into Windows for ages. If you think they can force toggle it or something, that won't work at all and deleting Windows 10 wouldn't make it easier.
    rovr138 · 1790968947 · focus · HN ↗
    So you're there's exactly 0 effort in managing things for multiple Windows versions, for anyone along the entirety of the ecosystem? From MS developer, third party developer, hardware, drivers, users, etc?
    How about testing? Do you think that there's no testing put out when a fix has to go out for 2 OS, regardless of how similar they are?
    > What problems are solved by getting all Windows users onto Windows 11 in particular?
    I have given a few. If you don't want to see it, that's fine.
    Dylan16807 · 1790971034 · focus · HN ↗
    Exactly 0? I said it's not "streamlined enormously".
    I would estimate that supporting both windows 10 and 11 is a single digit percentage harder than supporting just one of them.
    > I have given a few. If you don't want to see it, that's fine.
    Where? You said something vague about streamlining, and the only concrete example was something about "deploy ipv6" which Microsoft did back in Vista.

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