multi-party-schnorr 1.1.0

// Copyright (c) Silence Laboratories Pte. Ltd. All Rights Reserved.
// This software is licensed under the Silence Laboratories License Agreement.

use std::sync::Arc;

use crypto_bigint::rand_core::CryptoRngCore;
use ff::Field;
use rand::{CryptoRng, Rng, RngCore};

use crate::common::{
    schnorr_split_private_key,
    ser::Serializable,
    traits::{GroupElem, ScalarReduce},
    utils::support::{run_keygen, run_round},
};

use super::{messages::Keyshare, KeyRefreshData, KeygenError, KeygenParty, R0};

// Helper method to generate PKI for a set of parties.
pub fn generate_pki<R: CryptoRngCore>(
    total_parties: usize,
    rng: &mut R,
) -> (
    Vec<Arc<crypto_box::SecretKey>>,
    Vec<(u8, crypto_box::PublicKey)>,
) {
    let mut party_pubkey_list = vec![];

    let party_key_list: Vec<Arc<crypto_box::SecretKey>> = (0..total_parties)
        .map(|pid| {
            let sk = crypto_box::SecretKey::generate(rng);
            party_pubkey_list.push((pid as u8, sk.public_key()));
            Arc::new(sk)
        })
        .collect();

    (party_key_list, party_pubkey_list)
}

pub fn setup_keygen<G>(t: u8, n: u8) -> impl Iterator<Item = KeygenParty<R0, G>>
where
    G: GroupElem,
    G::Scalar: ScalarReduce<[u8; 32]>,
    G::Scalar: Serializable,
{
    let mut rng = rand::thread_rng();
    // Initializing the keygen for each party.
    let (party_key_list, party_pubkey_list) = generate_pki(n.into(), &mut rng);

    (0..n).map(move |idx| {
        KeygenParty::new(
            t,
            n,
            idx,
            party_key_list[idx as usize].clone(),
            party_pubkey_list.clone(),
            None,
            None,
            rng.gen(),
            None,
        )
        .unwrap()
    })
}

pub fn process_refresh<const T: usize, const N: usize, G: GroupElem>(
    shares: [Keyshare<G>; N],
) -> Result<[Keyshare<G>; N], KeygenError>
where
    G::Scalar: ScalarReduce<[u8; 32]>,
    G::Scalar: Serializable,
{
    let mut rng = rand::thread_rng();

    let refresh_data = shares
        .into_iter()
        .map(|data| data.get_refresh_data(None))
        .collect();

    let parties0 = setup_refresh(refresh_data, &mut rng)?;

    let (actors, msgs): (Vec<_>, Vec<_>) = run_round(parties0, ()).into_iter().unzip();

    let (actors, msgs): (Vec<_>, Vec<_>) = run_round(actors, msgs).into_iter().unzip();

    let new_shares = run_round(actors, msgs);

    Ok(new_shares
        .try_into()
        .map_err(|_| panic!("size will be N"))
        .unwrap())
}

pub fn setup_refresh<R: CryptoRng + RngCore, G>(
    shares: Vec<KeyRefreshData<G>>,
    rng: &mut R,
) -> Result<Vec<KeygenParty<R0, G>>, KeygenError>
where
    G: GroupElem,
    G::Scalar: ScalarReduce<[u8; 32]>,
    G::Scalar: Serializable,
{
    let (party_key_list, party_pubkey_list) = generate_pki(shares.len(), rng);
    let parties0 = shares
        .into_iter()
        .zip(party_key_list)
        .map(|(data, party_key)| {
            KeygenParty::new(
                data.threshold,
                data.total_parties,
                data.party_id,
                party_key,
                party_pubkey_list.clone(),
                Some(data),
                None,
                rng.gen(),
                None,
            )
        })
        .collect::<Result<Vec<_>, _>>()?;
    Ok(parties0)
}

pub fn run_refresh<const T: usize, const N: usize, G: GroupElem>() -> Result<(), KeygenError>
where
    G::Scalar: ScalarReduce<[u8; 32]>,
    G::Scalar: Serializable,
{
    let shares = run_keygen::<T, N, G>();
    process_refresh::<T, N, G>(shares)?;
    Ok(())
}

//
pub fn run_recovery<const T: usize, const N: usize, G: GroupElem>(
    keyshares: &[Keyshare<G>],
    lost_party_ids: Vec<u8>,
) -> Result<(), KeygenError>
where
    G::Scalar: ScalarReduce<[u8; 32]>,
    G::Scalar: Serializable,
{
    let mut rng = rand::thread_rng();
    let (party_key_list, party_pubkey_list) = generate_pki(N, &mut rng);

    // Start refresh protocol
    let mut parties0 = vec![];
    for pid in 0..N {
        let data = if lost_party_ids.contains(&(pid as u8)) {
            KeyRefreshData::recovery_data_for_lost(
                lost_party_ids.clone(),
                keyshares[0].public_key,
                pid as u8,
                T as u8,
                N as u8,
            )
        } else {
            keyshares[pid].get_refresh_data(Some(lost_party_ids.clone()))
        };

        parties0.push(KeygenParty::new(
            T as u8,
            N as u8,
            pid as u8,
            party_key_list[pid].clone(),
            party_pubkey_list.clone(),
            Some(data),
            None,
            rng.gen(),
            None,
        )?);
    }

    let (actors, msgs): (Vec<_>, Vec<_>) = run_round(parties0, ()).into_iter().unzip();
    let (actors, msgs): (Vec<_>, Vec<_>) = run_round(actors, msgs).into_iter().unzip();
    run_round(actors, msgs);

    Ok(())
}

pub fn run_import<const T: usize, const N: usize, G: GroupElem>() -> Result<(), KeygenError>
where
    G::Scalar: ScalarReduce<[u8; 32]>,
    G::Scalar: Serializable,
{
    //TODO: for testing purposes create a random key and chain code. In production those should be inputs
    let mut rng = rand::thread_rng();
    let private_key = G::Scalar::random(&mut rng);
    let shares = schnorr_split_private_key::<G, _>(&private_key, T as u8, N as u8, None, &mut rng);

    let parties = setup_refresh(shares.unwrap(), &mut rng).unwrap();

    let (actors, msgs): (Vec<_>, Vec<_>) = run_round(parties, ()).into_iter().unzip();
    let (actors, msgs): (Vec<_>, Vec<_>) = run_round(actors, msgs).into_iter().unzip();
    run_round(actors, msgs);
    Ok(())
}