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. zamalek · 1790879278 · focus · HN ↗
  Exactly. But that's why I think SHA was a mistake. He should have gone with something like murmur to avoid all this frothing at the mouth.
  1. Someone · 1790883791 · focus · HN ↗
    Linus, in 2005, couldn’t have gone for murmur, from 2008.
    Was there “something like murmur” in 2005 that’s cryptographically better than SHA1?
    sgerenser · 1790894620 · focus · HN ↗
    Yeah, in 2005, SHA-1 was just about the best you can do given the constraints of the time (without picking something much more esoteric, much slower, etc.). Using SHA-256 at that time would have been noticeably slower on the computers of the time, and made repo metadata take up a lot more space.

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