Noir Array Helpers

Noir Array Helpers is a Noir function library to manipulate arrays. This library serves a kitchen sink for various array functions the Noir community finds useful.

Installation

In your Nargo.toml file, add the following dependency:

[dependencies]
array_helpers = { tag = "v0.19.0", git = "https://github.com/colinnielsen/noir-array-helpers" }

then use it in your circuits:

use dep::std;
use dep::array_helpers;

fn main(){
    let pub_key: [u8; 64] = [...];

    let (pub_key_x, pub_key_y) = split_u8_64(pub_key);
    std::println(pub_key_x);
    std::println(pub_key_y);
}

or

use dep::std;
use dep::array_helpers::split_u8_64;

fn main(){
let eth_addr_u8: [u8;20] = [...];

    let addr = array_helpers::u8_to_eth_address(pub_key_x, pub_key_y);
    std::println(addr);

}

Usage

Here are the methods available in the library:

NOTE: this lib ships with constrained and unconstrained versions of each function, and are post-fixed with _unconstrained. (unconstrained is not currently implemented as of Noir v0.6.0, but will allow you to optimize your gate count if you do not need to constrain the computation of the function)

split_u8_64

Splits an array of u8 values, with a length of 64, into two arrays of u8 values, each with a length of 32.

fn split_u8_64(arr: [u8; 64]) -> ([u8; 32], [u8; 32])
fn split_u8_64_unconstrained(arr: [u8; 64]) -> ([u8; 32], [u8; 32])

u8_32_to_u8_64

Combines two arrays of u8 values, each of length 32, into a single array of u8 values, with a length of 64.

fn u8_32_to_u8_64(arr_a: [u8; 32], arr_b: [u8; 32]) -> [u8; 64]
fn u8_32_to_u8_64_unconstrained(arr_a: [u8; 32], arr_b: [u8; 32]) -> [u8; 64]

u8_to_u160

Converts an array of u8 values to a Field value, representing a u160 value.

NOTE: These are also aliased to u8_to_eth_address, for readability.

fn u8_to_u160(array: [u8]) -> Field
fn u8_to_u160_unconstrained(array: [u8]) -> Field

fn u8_to_eth_address(array: [u8]) -> Field
fn u8_to_eth_address_unconstrained(array: [u8]) -> Field

u8_32s_to_u64_16

Converts two arrays of u8 values, each of length 32, to a single array of u64 values, with a length of 16.

fn u8_32s_to_u64_16(arr_a: [u8; 32], arr_b: [u8; 32]) -> [u64; 16]
fn u8_32s_to_u64_16_unconstrained(arr_a: [u8; 32], arr_b: [u8; 32]) -> [u64; 16]

u64_4_to_u8_32

Converts an array of u64 values, with a length of 4, to an array of u8 values, with a length of 32.

fn u64_4_to_u8_32(array: [u64; 4]) -> [u8; 32]
fn u64_4_to_u8_32_unconstrained(array: [u64; 4]) -> [u8; 32]

License

This project is licensed under the MIT License. See the LICENSE file for details.