highwayhash(3)

✨ highwayhash — the manual page, but make it cute ✨

okay so bestie, you're reading the highwayhash(3) page from the Library Functions Manual and honestly? it's giving "fast strong 64-bit hash functions" energy and I am obsessed. let's get into it 💖

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🌸 NAME 🌸

highwayhash — fast strong 64-bit hash functions. yes that's it, that's the whole name, slay.

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🎀 SYNOPSIS 🎀

first up, the C girlies:

#include <highwayhash/c_bindings.h> /* C */

    uint64_t SipHashC(const uint64_t* key, const char* bytes, const
uint64_t size);

    uint64_t SipHash13C(const uint64_t* key, const char* bytes, const
uint64_t size);

    uint64_t HighwayHash64(const HHKey key, const char* bytes, const
uint64_t size);

and now the C++ besties:

#include <highwayhash/highwayhash.h> /* C++ */

    using namespace highwayhash;

    void HighwayHashT(State* HH_RESTRICT state,
                      const char* HH_RESTRICT bytes, const size_t size,
                      Result* HH_RESTRICT hash);

#include <highwayhash/sip_hash.h> /* C++ */

    using namespace highwayhash;

    HH_U64 SipHash(const SipHashState::Key& key, const char* bytes,const
HH_U64 size);

and when you link, you link with -lhighwayhash 🫶 don't forget her, she's the whole reason it works.

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💅 DESCRIPTION 💅

so hash functions are used everywhere, right? which means obviously we want them faster and safer. this package serves you two 'strong' hash functions — and by strong we mean well-distributed and unpredictable, not just "vibes are good":

• a faster version of SipHash
• and an even faster algorithm that they literally named HighwayHash 🛣️✨

SipHash is a fast but 'cryptographically strong' pseudo-random function, and it was made by Aumasson and Bernstein — the paper lives at https://www.131002.net/siphash/siphash.pdf if you want the lore.

HighwayHash is a new way of mixing inputs which may inspire new cryptographically strong hashes 👑 and the numbers?? iconic:

• Large inputs are processed at a rate of 0.24 cycles per byte ⚡
• latency stays low even for small inputs
• HighwayHash is faster than SipHash for all input sizes
• with 5 times higher throughput at 1 KiB

they discuss design choices and give you statistical analysis plus preliminary cryptanalysis over at https://arxiv.org/abs/1612.06257 — go read it, iykyk 📖

⚠️ also important bestie: note that SipHash wants an uint64_t[2] key while HighwayHash wants uint64_t[4]. do not mix those up, that's a whole different vibe and not the good kind 💀

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🌈 EXAMPLES 🌈

64-bit SipHash for any CPU:

#include "highwayhash/sip_hash.h"
using namespace highwayhash;
const HH_U64 key2[2] HH_ALIGNAS(16) = {1234, 5678};
char in[8] = {1};
return SipHash(key2, in, 8);

64, 128 or 256 bit HighwayHash for the CPU determined by compiler flags:

#include "highwayhash/highwayhash.h"
using namespace highwayhash;
const HHKey key HH_ALIGNAS(32) = {1, 2, 3, 4};
char in[8] = {1};
HHResult64 result;  // or HHResult128 or HHResult256
HHStateT<HH_TARGET> state(key);
HighwayHashT(&state, in, 8, &result);

64, 128 or 256 bit HighwayHash for the CPU on which we're currently running:

#include "highwayhash/highwayhash_target.h"
#include "highwayhash/instruction_sets.h"
using namespace highwayhash;
const HHKey key HH_ALIGNAS(32) = {1, 2, 3, 4};
char in[8] = {1};
HHResult64 result;  // or HHResult128 or HHResult256
InstructionSets::Run<HighwayHash>(key, in, 8, &result);

C-callable 64-bit HighwayHash for the CPU on which we're currently running:

#include "highwayhash/c_bindings.h"
const uint64_t key[4] = {1, 2, 3, 4};
char in[8] = {1};
return HighwayHash64(key, in, 8);

like... four whole flavours of the same gorgeous algorithm?? we ate 🍓

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👀 SEE ALSO 👀

• /usr/include/highwayhash/c_bindings.h (C)
• /usr/include/highwayhash/highwayhash.h (C++)

go read the headers, they're right there, they're free 💜

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💀 BUGS 💀

found something cursed? take it straight to the source, bestie:

• https://github.com/google/highwayhash/issues

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👑 AUTHOR 👑

the upstream authors are Jan Wassenberg <jan.wassenberg@gmail.com> and Jyrki Alakuijala <jyrki.alakuijala@gmail.com>, updated 2017-02-07 — legends, no cap.

this manpage was created by Adam Borowski <kilobyte@angband.pl>, and completed by Zhou Mo <cdluminate@gmail.com> according to upstream readme and header files. 🫶

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and that's the whole page!! this highwayhash(3) manual was brought to you by Library Functions Manual energy, dated April 25, 2017 — go hash something beautiful, mwah 💅✨