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Poseidon2 Plonky2

WARNING: This is a work-in-progress prototype, and has not received careful code review. This implementation is NOT ready for production use.

This crate is an implementation of the Poseidon2 Hash that can be employed in the Plonky2 proving system. Poseidon2 hash function is a new zk-friendly hash function, and provides good performance. The hash and gate implementations are based on the plonky2 Poseidon hash and gate.

The Poseidon2 Hash implementation is consistent with that in here: https://github.com/HorizenLabs/poseidon2

Code Organization

This crate include:

This crate can be used to:

Generate Plonky2 proofs employing the Poseidon2 hash function
Write Plonky2 circuits computing Poseidon2 hashes

Building

This crate requires the Rust nightly compiler due to the use of certain unstable features. To install the nightly toolchain, use rustup:

rustup install nightly

To ensure that the nightly toolchain is used when building this crate, you can set the override in the project directory:

rustup override set nightly

Alternatively, you can specify the nightly toolchain when building:

cargo +nightly build

Usage

The Poseidon2 hash can be used directly to compute hash values over an array of field elements. Below is a simplified example demonstrating how to use the Poseidon2 hash function:

use crate::poseidon2_hash::poseidon2::{Poseidon2, SPONGE_WIDTH};
use plonky2_field::goldilocks_field::GoldilocksField as F;
use plonky2_field::types::Field;

fn main() {
    // Create an input array of field elements for hashing
    let mut input = [F::ZERO; SPONGE_WIDTH];
    // [0,1,2,3,4,5,6,7,8,9,10,11]
    for i in 0..SPONGE_WIDTH {
        input[i] = F::from_canonical_u64(i as u64);
    }
    // Compute the Poseidon2 hash
    let output = F::poseidon2(input);
    // Print the input values
    for i in 0..SPONGE_WIDTH {
        println!("input {} = {}", i, input[i]);
    }
    // Print the output values
    for i in 0..SPONGE_WIDTH {
        println!("out {} = {}", i, output[i]);
    }
}

Benchmark Results

Benchmark results are shown in BENCHMARKS.md

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