Re: [PATCH v3 1/3] siphash: add cryptographically secure hashtable function

Jason A. Donenfeld
2016-12-14T20:58:33Z

Hey Tom,

Just following up on what I mentioned in my last email...

On Wed, Dec 14, 2016 at 8:35 PM, Jason A. Donenfeld <Jason@zx2c4.com> wrote:
> I think your suggestion for (2) will contribute to further
> optimizations for (1). In v2, I had another patch in there adding
> siphash_1word, siphash_2words, etc, like jhash, but I implemented it
> by taking u32 variables and then just concatenating these into a
> buffer and passing them to the main siphash function. I removed it
> from v3 because I thought that these kind of missed the whole point.
> In particular:
>
> a) siphash24_1word, siphash24_2words, siphash24_3words, etc should
> take u64, not u32, since that's what siphash operates on natively

I implemented these here:
https://git.zx2c4.com/linux-dev/commit/?h=siphash&id=4652b6f3643bdba217e2194d89661348bbac48a0

This will be part of the next version of the series I submit. It's not
immediately clear that using it is strictly faster than the struct
trick though. However, I'm not yet sure why this would be.

Jason