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Version: 0.5.1

Merkle Trees

check_membership​

Returns 1 if the specified leaf is at the given index on a tree

fn check_membership(_root : Field, _leaf : Field, _index : Field, _hash_path: [Field]) -> Field

example:

/**
 *
    index = "0"
    priv_key = "0x000000000000000000000000000000000000000000000000000000616c696365"
    secret = "0x1929ea3ab8d9106a899386883d9428f8256cfedb3c4f6b66bf4aa4d28a79988f"
    root = "0x2f36d4404719a30512af45be47c9732e916cb131933102b04ba6432602db209c"
    hash_path = [
    "0x1e61bdae0f027b1b2159e1f9d3f8d00fa668a952dddd822fda80dc745d6f65cc",
    "0x0e4223f3925f98934393c74975142bd73079ab0621f4ee133cee050a3c194f1a",
    "0x2fd7bb412155bf8693a3bd2a3e7581a679c95c68a052f835dddca85fa1569a40"
    ]
 */

fn main(root : Field, index : Field, hash_path : [Field; 3], secret: Field, priv_key: Field) {
    constrain index == index;

    let pubkey = std::scalar_mul::fixed_base(priv_key);
    let pubkey_x = pubkey[0];
    let pubkey_y = pubkey[1];
    let note_commitment = std::hash::pedersen([pubkey_x, pubkey_y, secret]);

    let root = std::merkle::check_membership(root, note_commitment[0], index, hash_path);
    std::println(root);
}

check_membership_in_noir​

Behaves exactly the same as above, but it's computed in Noir in order to accept many backends.

fn check_membership_in_noir(root : Field, leaf : Field, index : Field, hash_path: [Field]) -> Field

For examples, you can literally replace check_membership for this method, in the above example.

compute_root_from_leaf​

Returns the root of the tree from the provided leaf and its hash path, using a pedersen hash

fn compute_root_from_leaf(leaf : Field, index : Field, hash_path: [Field]) -> Field

example:

/**
    index = "0"
    priv_key = "0x000000000000000000000000000000000000000000000000000000616c696365"
    secret = "0x1929ea3ab8d9106a899386883d9428f8256cfedb3c4f6b66bf4aa4d28a79988f"
    note_hash_path = [
    "0x1e61bdae0f027b1b2159e1f9d3f8d00fa668a952dddd822fda80dc745d6f65cc",
    "0x0e4223f3925f98934393c74975142bd73079ab0621f4ee133cee050a3c194f1a",
    "0x2fd7bb412155bf8693a3bd2a3e7581a679c95c68a052f835dddca85fa1569a40"
    ]
 */
fn main(index : Field, priv_key : Field, secret : Field, note_hash_path : [Field; 3]) {
    constrain index == index;

    let pubkey = std::scalar_mul::fixed_base(priv_key);
    let pubkey_x = pubkey[0];
    let pubkey_y = pubkey[1];
    let note_commitment = std::hash::pedersen([pubkey_x, pubkey_y, secret]);

    let root = std::merkle::compute_root_from_leaf(note_commitment[0], index, note_hash_path);
    std::println(root);
}

compute_merkle_root​

Returns the root of the tree from the provided leaf and its hash path, using a pedersen hash.

#[foreign(compute_merkle_root)]
fn compute_merkle_root(_leaf : Field, _index : Field, _hash_path: [Field]) -> Field {}
info

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