helios/consensus/src/utils.rs

use blst::{
    min_pk::{PublicKey, Signature},
    BLST_ERROR,
};
use common::{types::Bytes32, utils::bytes32_to_node};
use eyre::Result;
use ssz_rs::prelude::*;

use crate::types::{Header, SignatureBytes};

pub fn calc_sync_period(slot: u64) -> u64 {
    let epoch = slot / 32; // 32 slots per epoch
    epoch / 256 // 256 epochs per sync committee
}

pub fn is_aggregate_valid(sig_bytes: &SignatureBytes, msg: &[u8], pks: &[&PublicKey]) -> bool {
    let dst: &[u8] = b"BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_";
    let sig_res = Signature::from_bytes(sig_bytes);
    match sig_res {
        Ok(sig) => sig.fast_aggregate_verify(true, msg, dst, pks) == BLST_ERROR::BLST_SUCCESS,
        Err(_) => false,
    }
}

pub fn is_proof_valid<L: Merkleized>(
    attested_header: &Header,
    leaf_object: &mut L,
    branch: &[Bytes32],
    depth: usize,
    index: usize,
) -> bool {
    let res: Result<bool> = (move || {
        let leaf_hash = leaf_object.hash_tree_root()?;
        let state_root = bytes32_to_node(&attested_header.state_root)?;
        let branch = branch_to_nodes(branch.to_vec())?;

        let is_valid = is_valid_merkle_branch(&leaf_hash, branch.iter(), depth, index, &state_root);
        Ok(is_valid)
    })();

    if let Ok(is_valid) = res {
        is_valid
    } else {
        false
    }
}

#[derive(SimpleSerialize, Default, Debug)]
struct SigningData {
    object_root: Bytes32,
    domain: Bytes32,
}

#[derive(SimpleSerialize, Default, Debug)]
struct ForkData {
    current_version: Vector<u8, 4>,
    genesis_validator_root: Bytes32,
}

pub fn compute_signing_root(object_root: Bytes32, domain: Bytes32) -> Result<Node> {
    let mut data = SigningData {
        object_root,
        domain,
    };
    Ok(data.hash_tree_root()?)
}

pub fn compute_domain(
    domain_type: &[u8],
    fork_version: Vector<u8, 4>,
    genesis_root: Bytes32,
) -> Result<Bytes32> {
    let fork_data_root = compute_fork_data_root(fork_version, genesis_root)?;
    let start = domain_type;
    let end = &fork_data_root.as_bytes()[..28];
    let d = [start, end].concat();
    Ok(d.to_vec().try_into().unwrap())
}

fn compute_fork_data_root(
    current_version: Vector<u8, 4>,
    genesis_validator_root: Bytes32,
) -> Result<Node> {
    let mut fork_data = ForkData {
        current_version,
        genesis_validator_root,
    };
    Ok(fork_data.hash_tree_root()?)
}

pub fn branch_to_nodes(branch: Vec<Bytes32>) -> Result<Vec<Node>> {
    branch
        .iter()
        .map(bytes32_to_node)
        .collect::<Result<Vec<Node>>>()
}