Re: [PATCH 00/12] crypto: sha256 - Use partial block API

[Herbert Xu <herbert@gondor.apana.org.au>]

On Wed, Apr 30, 2025 at 10:45:43AM -0700, Eric Biggers wrote:
>
> As for your sha256_finup "optimization", it's an interesting idea, but
> unfortunately it slightly slows down the common case which is count % 64 < 56,
> due to the unnecessary copy to the stack and the following zeroization.  In the
> uncommon case where count % 64 >= 56 you do get to pass nblocks=2 to
> sha256_blocks_*(), but ultimately SHA-256 is serialized block-by-block anyway,
> so it ends up being only slightly faster in that case, which again is the
> uncommon case.  So while it's an interesting idea, it doesn't seem to actually
> be better.  And the fact that that patch is also being used to submit unrelated,
> more dubious changes isn't very helpful, of course.

I'm more than willing to change sha256_finup if you can prove it
with real numbers that it is worse than the single-block version.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt