Hash methods

sha256

Given an array of bytes, returns the resulting sha256 hash.

fn sha256(_input : [u8]) -> [u8; 32]

example:

fn main() {
    let x = [163, 117, 178, 149]; // some random bytes
    let hash = std::hash::sha256(x);
}

info

This is a black box function. Read this section to learn more about black box functions in Noir.

blake2s

Given an array of bytes, returns an array with the Blake2 hash

fn blake2s(_input : [u8]) -> [u8; 32]

example:

fn main() {
    let x = [163, 117, 178, 149]; // some random bytes
    let hash = std::hash::blake2s(x);
}

info

This is a black box function. Read this section to learn more about black box functions in Noir.

pedersen

Given an array of Fields, returns the Pedersen hash.

fn pedersen(_input : [Field]) -> [Field; 2]

example:

fn main() {
    let x = [163, 117, 178, 149]; // some random bytes
    let hash = std::hash::pedersen(x);
}

info

This is a black box function. Read this section to learn more about black box functions in Noir.

keccak256

Given an array of bytes (u8), returns the resulting keccak hash as an array of 32 bytes ([u8; 32]). Specify a message_size to hash only the first message_size bytes of the input.

fn keccak256<N>(_input : [u8; N], _message_size: u32) -> [u8; 32]

example:

fn main() {
    let x = [163, 117, 178, 149]; // some random bytes
    let message_size = 4;
    let hash = std::hash::keccak256(x, message_size);
}

info

This is a black box function. Read this section to learn more about black box functions in Noir.

poseidon

Given an array of Fields, returns a new Field with the Poseidon Hash. Mind that you need to specify how many inputs are there to your Poseidon function.

// example for hash_1, hash_2 accepts an array of length 2, etc
fn hash_1(input: [Field; 1]) -> Field

example:

fn main()
{
  let hash1 = std::hash::poseidon::bn254::hash_2([1, 2]);
  assert(hash1 == 0x115cc0f5e7d690413df64c6b9662e9cf2a3617f2743245519e19607a4417189a);
}

mimc_bn254 and mimc

mimc_bn254 is mimc, but with hardcoded parameters for the BN254 curve. You can use it by providing an array of Fields, and it returns a Field with the hash. You can use the mimc method if you're willing to input your own constants:

fn mimc<N>(x: Field, k: Field, constants: [Field; N], exp : Field) -> Field

otherwise, use the mimc_bn254 method:

fn mimc_bn254<N>(array: [Field; N]) -> Field

example:

fn main() {
    let x = [163, 117, 178, 149]; // some random bytes
    let hash = std::hash::mimc_bn254(x);
}

hash_to_field

fn hash_to_field<N>(_input : [Field; N]) -> Field {}

Calculates the blake2s hash of the inputs and returns the hash modulo the field modulus to return a value which can be represented as a Field.

info

This is a black box function. Read this section to learn more about black box functions in Noir.