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use crate::error::{Error, ErrorKind};
pub use ckb_crypto::secp::{Error as Secp256k1Error, Message, Privkey, Pubkey, Signature};
use ckb_logger::{debug, trace};
use std::collections::HashSet;
use std::hash::BuildHasher;
pub fn verify_m_of_n<S>(
message: &Message,
m_threshold: usize,
sigs: &[Signature],
pks: &HashSet<Pubkey, S>,
) -> Result<(), Error>
where
S: BuildHasher,
{
if sigs.len() > pks.len() {
return Err(ErrorKind::SigCountOverflow.into());
}
if m_threshold > sigs.len() {
return Err(ErrorKind::SigNotEnough.into());
}
let mut used_pks: HashSet<Pubkey> = HashSet::with_capacity(m_threshold);
let verified_sig_count = sigs
.iter()
.filter_map(|sig| {
trace!(
"recover sig {:x?} with message {:x?}",
&sig.serialize()[..],
message.as_ref()
);
match sig.recover(&message) {
Ok(pubkey) => Some(pubkey),
Err(err) => {
debug!("recover secp256k1 sig error: {}", err);
None
}
}
})
.filter(|rec_pk| pks.contains(rec_pk) && used_pks.insert(rec_pk.to_owned()))
.take(m_threshold)
.count();
if verified_sig_count < m_threshold {
return Err(ErrorKind::Threshold {
pass_sigs: verified_sig_count,
threshold: m_threshold,
}
.into());
}
Ok(())
}
#[cfg(test)]
mod tests {
use super::*;
use rand::{thread_rng, Rng};
fn random_message() -> Message {
let mut data = [0; 32];
thread_rng().fill(&mut data[..]);
loop {
if let Ok(msg) = Message::from_slice(&data) {
return msg;
}
}
}
fn random_signature(message: &Message) -> Signature {
let secret_key = random_secret_key();
secret_key.sign_recoverable(message).expect("sign")
}
fn random_secret_key() -> Privkey {
let mut data = [0; 32];
thread_rng().fill(&mut data[..]);
loop {
let key = Privkey::from_slice(&data);
if key.pubkey().is_ok() {
return key;
}
}
}
#[test]
fn test_m_of_n() {
let test_set = [
(2, vec![true, true], 3, Ok(())),
(2, vec![true, true, true], 3, Ok(())),
(3, vec![true, true, true], 3, Ok(())),
(3, vec![true, false, true, true], 4, Ok(())),
(
2,
vec![true, true, true],
1,
Err(ErrorKind::SigCountOverflow),
),
(3, vec![true, true], 3, Err(ErrorKind::SigNotEnough)),
(
3,
vec![true, true, false],
3,
Err(ErrorKind::Threshold {
pass_sigs: 2,
threshold: 3,
}),
),
];
for (threshold, sigs, pks, result) in test_set.iter() {
let message = random_message();
let sks: Vec<Privkey> = (0..sigs.len()).map(|_| random_secret_key()).collect();
let pks: HashSet<Pubkey> = sks
.iter()
.enumerate()
.map(|(_i, sk)| sk.pubkey().expect("pk"))
.take(*pks)
.collect();
let sigs: Vec<Signature> = sigs
.iter()
.enumerate()
.map(|(i, valid)| {
if *valid {
sks[i].sign_recoverable(&message).expect("sign")
} else {
random_signature(&message)
}
})
.collect();
let verify_result =
verify_m_of_n(&message, *threshold, &sigs, &pks).map_err(|err| err.kind());
assert_eq!(&verify_result, result);
}
}
#[test]
fn test_2_of_3_with_wrong_signature() {
let message = random_message();
let sks: Vec<Privkey> = (0..3).map(|_| random_secret_key()).collect();
let pks: HashSet<Pubkey> = sks.iter().map(|sk| sk.pubkey().expect("pk")).collect();
let sigs: Vec<Signature> = vec![
sks[0].sign_recoverable(&message).expect("sign"),
sks[2].sign_recoverable(&message).expect("sign"),
random_signature(&message),
];
let verify_result = verify_m_of_n(&message, 2, &sigs, &pks);
assert!(verify_result.is_ok());
}
#[test]
fn test_duplicate_pubkeys() {
let message = random_message();
let sks: Vec<Privkey> = (0..3).map(|_| random_secret_key()).collect();
let pks: HashSet<Pubkey> = sks.iter().map(|sk| sk.pubkey().expect("pk")).collect();
let sigs: Vec<Signature> = vec![
sks[0].sign_recoverable(&message).expect("sign"),
sks[0].sign_recoverable(&message).expect("sign"),
random_signature(&message),
];
let verify_result = verify_m_of_n(&message, 2, &sigs, &pks).map_err(|err| err.kind());
assert_eq!(
verify_result,
Err(ErrorKind::Threshold {
pass_sigs: 1,
threshold: 2
})
);
}
}