This is an optimized C++ implementation of Equihash, the memory-hard Proof-of-Work with fast verification. Equihash is designed by Alex Biryukov and Dmitry Khovratovich, cryptographers at the University of Luxembourg.
Equihash is an asymmetric proof-of-work algorithm based on a computationally hard generalized birthday problem, which requires a lot of memory to generate a proof, but is instant to verify. Equihash is adapted as the PoW in Zcash a public implementation of the cryptocurrency protocol Zerocash. It is possible to use Equihash in TLS as a client puzzle.
Equihash has two parameters: N (width in bits) and K (length), which determine the complexity of the underlying problem and thus the memory and time complexity of the Equihash PoW. The underlying hash function is Blake2b, but any collision-resistant hash function would work too.
The time complexity is proportional to K2^{N/(K+1)}, and memory complexity to 2^{K+N/(K+1)}. The proof size is 2^{K}(1+N/(K+1))+192 bits. Verification requires 2^K hashes and XORs.
Please report bugs as issues on this repository.
For cryptocurrencies: (100/110/120,4), (108/114/120/126,5).
For client puzzles: (60/70/80/90,4), (90/96/102,5).
make builds the executable equihash.
equihash is a command-line utility to test specific Equihash instances
on your system. To show usage instructions, run
./equihash without arguments as
Usage: ./equihash -n N -k K -s Seed
Parameters:
N The width (number of bits) of the generalized birthday problem, integer divisible by (K+1)
K The length of the generalized birthday problem, small integer
Seed Seed for the problem, to distinguish between solutions. Integer.
For example, to compute Equihash using N=120 and k=5, consuming at least 32 MB of RAM
$ ./equihash -n 120 -k 5 -s 3
The Equihash code in this repository is copyright (c) 2016 Dmitry Khovratovich (University of Luxembourg) under CC0 license.
The license is GPL-compatible.