SeaHash: Explained

Discussion that came up the other week for those that missed it.<p><a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=13057797" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=13057797</a>

&gt; `f : {0,1}^n → {0,1}^n` is a perfect PRF if and only if given a distribution `d : {0,1}^n → [0,1]`, `f` maps inputs following the distribution `d` to the uniform distribution.<p>Is this even possible? If the distribution `d` always returns 0, how can a function make it uniform?<p>It would be nice, if the article would go into more details on how SeaHash obtains this property, and how it related to collision avoidance.

ticki and the rest of the crew working on Redox (jackpot51) are really doing some neat stuff. a lot of it is over my head but it is cool to see something being built from the ground up using some new techniques and ideas.

Could someone explain what the point is? Is there a use-case for this for &quot;general hashing&quot; and such, where sha256 is _genuinely_ insufficient?

&gt; SeaHash has mathematically provable statistical guarantees<p>I&#x27;m all for proofs but would love to see an empirical head-to-head against metroHash. Is it as good or better output distribution?

&gt; there is a major difference between cryptographic and non-cryptographic hash functions. SeaHash is not cryptographic<p>Is this in reference to most used hash functions not leaving any way to trace the contents of what was hashed, or not being able to reliably reconstruct contents to generate a certain hash? Or something else entirely?

I&#x27;ve been using blake2(b) for file hashing in some content addressable db stuff. What might be a scenario where i would choose Seahash over Blake2?<p>My main concern was speed and assurance that i would not see collisions. Beyond that, i am clearly naive on the subject.

Previous discussion: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=13057797" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=13057797</a>

How does this compare to murmurhash3?