On: Reasons to Prefer Blake3 over Sha256

[coppsilgold]

sha256 is not slow on modern hardware. openssl doesn't have blake3, but here is blake2:

    type             16 bytes     64 bytes    256 bytes   1024 bytes   8192 bytes  16384 bytes
    BLAKE2s256        75697.37k   308777.40k   479373.40k   567875.81k   592687.09k   591254.18k
    BLAKE2b512        63478.11k   243125.73k   671822.08k   922093.51k  1047833.51k  1048959.57k
    sha256           129376.82k   416316.32k  1041909.33k  1664480.49k  2018678.67k  2043838.46k

This is with the x86 sha256 instructions: sha256msg1, sha256msg2, sha256rnds2

[dralley → coppsilgold]

"modern hardware" deserves some caveats. AMD has supported those extensions since the original Zen, but Intel CPUs generally lacked them until only about 2 years ago.

[adrian_b → dralley]

For many years, starting in 2016, Intel has supported SHA-256 only in their Atom CPUs.

The reason seems to be that the Atom CPUs were compared in Geekbench with ARM CPUs, and without hardware SHA the Intel CPUs would have obtained worst benchmark scores.

In their big cores, SHA has been added in 2019, in Ice Lake (while Comet Lake still lacked it, being a Skylake derivative), and since then all newer Intel CPUs have it.

So except for the Intel Core CPUs, the x86 and ARM CPUs have had hardware SHA for at least 7 years, while the Intel Core CPUs have had it for the last 4 years.

[dralley → adrian_b]

>SHA has been added in 2019, in Ice Lake (while Comet Lake still lacked it, being a Skylake derivative)

Ice Lake was effectively a paper launch with low volume, repeated delays and mediocre performance. The server CPUs weren't released until 2021.

In terms of relevant quantities and relevant markets (e.g. not Atom or gaming laptops), Intel CPUs have only been "shipping" with those extensions for around 2.5 years, not 4.