👯 Discohash

2-5GB/s, passed SMHasher

Discohash (also known as BEBB4185) is a super simple and super fast hash that passes all of SMHasher, and runs at 2-5GB/s (depending on hardware) in this naive, portable, serial implementation.

Link to the SUPERCOP ECRYPT benchmark for bebb4185

Cryptanalysis

Cryptanalysis Open

Inviting all budding hashbreakers to attack the 128-bit version. Should be easy, right?

If you'd like something a little more challenging, try breaking beamsplitter-128

Submit your results as PR requests updating the README to a link to your analysis, or contact Cris directly.

Important Note The 128-bit variants must be modified from the existing source C/C++ files. Find the commented out lines at the end of the main hash function, and return 128-bits, instead of 64.

CLI app included

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Quick Facts

• A super-fast 64-bit hash.
• one of the fastest hashes ever benchmarked at ecrypt
• ECRYPT benchmark is 4x faster than BLAKE3
• Mix is super simple.
• Tested at ~ 5GB/s @ 3Gz, (Google Cloud Platform, N1 CPU)
• Passes all SMHasher tests.
• Also known as: BEBB4185
• Implemented in C++, and also a port to JS
• This repo includes a simple CLI app for hashing files or stdin from the command line.

Simplicity

The main 128-bit-to-128-bit mixing function is just this:

  mix(const int A)
    {
      const int B = A+1;
      
      ds[A] *= P;
      ds[A] = rot(ds[A], 23);
      ds[A] *= Q;
      
      ds[B] ^= ds[A];

      ds[B] *= P;
      ds[B] = rot(ds[B], 23);
      ds[B] *= Q;
    }

which is just multiplications by two 64-bit primes, P and Q, bit rotation, and xor.

P, and Q are:

• P = 0xFFFFFFFFFFFFFFFF - 58
• Q = 13166748625691186689

The standard internal state is 256-bits and the mixing function windows across that.

The standard digest is 64-bits, but you can modify it to yield 128-bits or more if you want a cryptographically secure hash.

Using

Use the C code from this repository, either in your project or as a CL-app (included):

cd src
./build.sh
./bin/bebbsum < 0xa2a647993898a3df.txt
> 0xa2a647993898a3df
./bin/bebbsum 0xa2a647993898a3df.txt
> 0xa2a647993898a3df

or, for a JS implementation:

npm i --save bebb4185

Use in Node.JS:

import {discohash} from 'bebb4185'

Or using Snowpack as a webmodule:

import {discohash} from './web_modules/bebb4185.js';

Then call it:

const hash = discohash(string_or_typed_array_key, optional_seed);

JS Implementation

• The JS Implementation produces the same value hashes as the C++ implementation.
• The JS implementation is ~ 500x slower than the C++ implementation.
• This is probably because of the use of BigInts to stand in for uint64_t
• It's possible to implement a 64-bit mult using 32-bit view which would remove the need for BigInt. I have no plan to do this.

SMHasher verification value

The value is: BEBB4185

Possible future work

Make a parallel version using Merkle tree