Thread

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

570 points · 536 comments · chmaynard

meinersbur · 1790878728 · focus · HN ↗
Linus Torvalds in 2007:
> but the point is the SHA-1, as far as Git is concerned, isn't even a security feature. It's purely a consistency check. The security parts are elsewhere, so a lot of people assume that since Git uses SHA-1 and SHA-1 is used for cryptographically secure stuff, they think that, Okay, it's a huge security feature. It has nothing at all to do with security, it's just the best hash you can get. ... [1]
[1] <a href="https://www.youtube.com/watch?v=4XpnKHJAok8&t=56m20s" rel="nofollow">https://www.youtube.com/watch?v=4XpnKHJAok8&t=56m20s
So Torvalds used SHA-1 purely because he needed a hash function with no other property than identifying content.
1. creata · 1790907291 · focus · HN ↗
  > It's purely a consistency check. The security parts are elsewhere
  Sorry if the video answers this, but how does commit signing work if it doesn't rely on the hash algorithm being resistant to at least second-preimage attacks?
  1. someonebaggy · 1790914467 · focus · HN ↗
    Things changed since 2007
    xeyownt · 1790938682 · focus · HN ↗
    How they changed?
    For all practical purpose SHA-1 is a bad hash function, it's slow, it's insecure.
    If SHA-1 is not a security measure, why do you even sign the commit. It doesn't make any sense. You give a strong signature on something weak.
    someonebaggy · 1790940619 · focus · HN ↗
    Well they didn't sign commits in 2007, and there wasn't github in 2007, so it wasn't a security measure in 2007.

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