Module 0x2::poseidon

Module which defines instances of the poseidon hash functions.

• Constants
• Function poseidon_bn254
• Function poseidon_bn254_internal

use 0x2::bcs;

Constants

The field size for BN254 curve.

const BN254_MAX: u256 = 21888242871839275222246405745257275088548364400416034343698204186575808495617;

Error if an empty vector is passed as input.

const EEmptyInput: u64 = 1;

Error if any of the inputs are larger than or equal to the BN254 field size.

const ENonCanonicalInput: u64 = 0;

Function poseidon_bn254

@param data: Vector of BN254 field elements to hash.

Hash the inputs using poseidon_bn254 and returns a BN254 field element.

Each element has to be a BN254 field element in canonical representation so it must be smaller than the BN254 scalar field size which is 21888242871839275222246405745257275088548364400416034343698204186575808495617.

public fun poseidon_bn254(data: &vector<u256>): u256

Implementation

public fun poseidon_bn254(data: &vector<u256>): u256 {
    let (mut i, mut b, l) = (0, vector[], data.length());
    assert!(l > 0, EEmptyInput);
    while (i < l) {
        let field_element = &data[i];
        assert!(*field_element < BN254_MAX, ENonCanonicalInput);
        b.push_back(bcs::to_bytes(&data[i]));
        i = i + 1;
    };
    let binary_output = poseidon_bn254_internal(&b);
    bcs::new(binary_output).peel_u256()
}

Function poseidon_bn254_internal

@param data: Vector of BN254 field elements in little-endian representation.

Hash the inputs using poseidon_bn254 and returns a BN254 field element in little-endian representation.

fun poseidon_bn254_internal(data: &vector<vector<u8>>): vector<u8>

Implementation

native fun poseidon_bn254_internal(data: &vector<vector<u8>>): vector<u8>;