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Comment by pclmulqdq | Hacker News Reader

Most people who publicly opine on the Blake vs. SHA2 debate seem to be relatively uninformed on the realities of each one. SHA2 and the Blakes are both usually considered to be secure.

The performance arguments most people make are also outdated or specious: the original comparisons of Blake vs SHA2 performance on CPUs were largely done before Intel and AMD had special SHA2 instructions.

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The author is one of the creators of blake3, Zooko.

Sorry, I should have been more precise. JP Aumasson is specifically who I'm thinking of; he's made the semi-infamous claim that SHA2 won't be broken in his lifetime. The subtext I gather is that there's just nothing on the horizon that's going to get it. SHA1 we saw coming a ways away!

Quoting directly from https://nostarch.com/crypto-dictionary under the entry SHA-2:

> Unlike SHA-1, SHA-2 algorithms aren’t broken and are unlikely to ever be.

There's also the fact NIST themselves deprecated SHA-1 in 2011 (https://csrc.nist.gov/news/2017/research-results-on-sha-1-co... not mentioned, but otherwise nice timeline here: https://crypto.stackexchange.com/a/60655), yet SHA-2 is still OK. Wiki has a table of cryptanalysis of SHA-2: https://en.wikipedia.org/wiki/SHA-2#Cryptanalysis_and_valida...

The summary is that either you attack a very reduced round variant and you get "practical" complexity for the attack, or you attack almost a full round variant and you get an entirely practical attack.

So I think your interpretation of the subtext is entirely correct.

Who I'm sure actually is informed, but in this particular case is tweeting things that do honestly sound like one of the uninformed commentators pclmulqdq mentioned. I'm not sure why, since as tptacek said, blake3 is good and maybe even preferable on it's own merits without venturing into FUD territory. And if you still wanted to get into antiquated design arguments, picking on SHA256's use of a construction that allows length extension attacks seems like more fair game.

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