Chaskey rotation numbers for halfsiphash

veorq / SipHash

High-speed secure pseudorandom function for short messages

Apache License 2.0

664 stars 50 forks source link

Chaskey rotation numbers for halfsiphash #5

Closed funny-falcon closed 7 years ago

funny-falcon commented 7 years ago

http://mouha.be/chaskey/

veorq commented 7 years ago

Thanks again, should have thought of those! Added in 7ce7f0470961555956a12cdf81474e68d1e89610

pishposh commented 7 years ago

@veorq Hi! I noticed the second pair of rotation constants in HalfSipHash (v₃ <<<= 7, v₁ <<<= 13) is swapped as compared to Chaskey’s constants (v₃ <<<= 13, v₁ <<<= 7). I’m not sure how much it matters, but is this intentional?

veorq commented 7 years ago

Yeah that's a known difference, not a problem, thanks for reporting though :)

pishposh commented 7 years ago

Thanks, just checking! Does it improve avalanche or something? I’d be curious to know why the swap.