wyhash
smhasher
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wyhash
- Wyhash: The fastest quality hash function
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What hash function you use for hash maps / hash tables?
I recently switched to wyhash as it seems to have a good combination of speed and stability.
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Are there any weaker hashes than MD5, but still randomly distributed?
wyhash is a decent option for if you don't need a cryptographical quality hash
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Hacker News top posts: Mar 15, 2021
New Bare Hash Map: 2X-3X Speedup over SOTA\ (32 comments)
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New Bare Hash Map: 2X-3X Speedup over SOTA
I feel like you’d want something a bit safer than “we don’t store the keys and just rely on the hash to be really good” [1], putting “please do not use this for serious tasks” in a comment embedded in the header file isn’t a clear enough warning.
It’s not clear to me that that probability of collision assumptions hold. It’s basically assuming that the hashing is perfect and distributes any inputs to the full 64-bit space with uniform probability. That’s the usual hash map / randomized algorithm hope, but does BigCrush or similar avalanche testing really prove that? (Presumably not, otherwise there wouldn’t be image attacks for things like md5).
[1] https://github.com/wangyi-fudan/wyhash/blob/d2a305811972f391...
- wyhash and wyrand are a non-cryptographic 64-bit hash function and PRNG respectively
smhasher
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New Bare Hash Map: 2X-3X Speedup over SOTA
The meow 0.4 was faster at short keys, but failed at the smhasher "LongNeighborTest" [1]. However, doubling the AES rounds makes it pass that test. Two rounds is enough for full diffusion in AES [2]. I recently looked at computing 4 Meow keys per hash function [3], and found the speedup to be almost 2x in a microbench. That puts it in rare territory for hash speed.
[1] https://github.com/injinj/smhasher/
[2] Section 5.4 of Introduction to Cryptography by Trappe and Washington -- It can be shown that two rounds are sufficient to obtain full diffusion, namely, each of the 128 output bits depends on each of the 128 input bits.
[3] https://github.com/raitechnology/raikv/blob/3ce2b23e0d9853fe...
What are some alternatives?
smhasher - Hash function quality and speed tests
meow_hash - Official version of the Meow hash, an extremely fast level 1 hash
aHash - aHash is a non-cryptographic hashing algorithm that uses the AES hardware instruction
leocad - A CAD application for creating virtual LEGO models
smhasher - Automatically exported from code.google.com/p/smhasher
Mersenne-Twister-in-Python - A Mersenne Twister Random Number Generator
countwords - Playing with counting word frequencies (and performance) in various languages.
houndsniff - Hash identification program.
securitytxt.org - Static website for security.txt.
prvhash - PRVHASH - Pseudo-Random-Value Hash. Hash functions, PRNG with unlimited period, randomness extractor, and a glimpse into abyss. (inline C/C++) (Codename Gradilac/Градилак)