‹ BackHN Continuity

Thread

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

570 points · 536 comments · chmaynard

  1. bawolff · · focus · HN ↗
    I think the only good argument here is that sha is maybe not a security control for git. I think every other argument in this article is incorrect

    a) it's relatively fast and impossible in a practical sense for two different files to accidentally hash to the same value.

    That is silly. We are not worried about accidentally triggering. We are worried about intentional triggers.

    I dont know why people always bring this up for hashing. In any other context it would be considered silly. If someone said, the chance of triggering a buffer overflow by accident is low, we would call that silly as we aren't worried about accidental triggers.

    b) second pre-image vs collision. In a world of open source where we accept commits from randoms on the internet, i think collisions are just as relavent as second pre-image.

    1. eviks · · focus · HN ↗
      a) it's silly to stop reading at that quote because the following text deals with "identification"

      b) so, you agree with the blog? "So, any realistic interesting attack vector therefore relies on a collision attack,"

      1. bawolff · · focus · HN ↗
        > b) so, you agree with the blog? "So, any realistic interesting attack vector therefore relies on a collision attack,"

        My reading of the blog is that they are dismissive of collision attacks. In context of git, i disagree. I think there are plausible attack scenarios involving collisions, or at least, just as plausible as second pre-image.

        If you mean do i agree with the blog that impossible attacks aren't possible? well yes obviously, but i think that goes without saying.

Open on Hacker News to reply ↗

Unofficial Hacker News client; not affiliated with Y Combinator.