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use ark_ec::{AffineCurve, PairingEngine};
use ark_serialize::CanonicalSerialize;
use ark_std::rand::RngCore;
use ark_std::UniformRand;
use ark_std::{cfg_iter_mut, collections::BTreeMap, io::Write, vec::Vec};
use schnorr_pok::{SchnorrChallengeContributor, SchnorrCommitment};
use zeroize::Zeroize;
use crate::error::ProofSystemError;
use crate::statement_proof::{PedersenCommitmentProof, StatementProof};
#[cfg(feature = "parallel")]
use rayon::prelude::*;
#[derive(Clone, Debug, PartialEq, Eq)]
pub struct SchnorrProtocol<'a, G: AffineCurve> {
pub id: usize,
pub commitment_key: &'a [G],
pub commitment: G,
pub commitment_to_randomness: Option<SchnorrCommitment<G>>,
pub witnesses: Option<Vec<G::ScalarField>>,
}
impl<'a, G: AffineCurve> SchnorrProtocol<'a, G> {
pub fn new(id: usize, commitment_key: &'a [G], commitment: G) -> Self {
Self {
id,
commitment_key,
commitment,
commitment_to_randomness: None,
witnesses: None,
}
}
pub fn init<R: RngCore>(
&mut self,
rng: &mut R,
mut blindings: BTreeMap<usize, G::ScalarField>,
witnesses: Vec<G::ScalarField>,
) -> Result<(), ProofSystemError> {
if self.commitment_to_randomness.is_some() {
return Err(ProofSystemError::SubProtocolAlreadyInitialized(self.id));
}
let blindings = (0..witnesses.len())
.map(|i| {
blindings
.remove(&i)
.unwrap_or_else(|| G::ScalarField::rand(rng))
})
.collect::<Vec<_>>();
self.commitment_to_randomness =
Some(SchnorrCommitment::new(&self.commitment_key, blindings));
self.witnesses = Some(witnesses);
Ok(())
}
pub fn challenge_contribution<W: Write>(&self, mut writer: W) -> Result<(), ProofSystemError> {
if self.commitment_to_randomness.is_none() {
return Err(ProofSystemError::SubProtocolNotReadyToGenerateChallenge(
self.id,
));
}
self.commitment_key.serialize_unchecked(&mut writer)?;
self.commitment.serialize_unchecked(&mut writer)?;
self.commitment_to_randomness
.as_ref()
.unwrap()
.challenge_contribution(writer)?;
Ok(())
}
pub fn gen_proof_contribution<E: PairingEngine>(
&mut self,
challenge: &G::ScalarField,
) -> Result<StatementProof<E, G>, ProofSystemError> {
Ok(StatementProof::PedersenCommitment(
self.gen_proof_contribution_as_struct(challenge)?,
))
}
pub fn gen_proof_contribution_as_struct(
&mut self,
challenge: &G::ScalarField,
) -> Result<PedersenCommitmentProof<G>, ProofSystemError> {
if self.commitment_to_randomness.is_none() {
return Err(ProofSystemError::SubProtocolNotReadyToGenerateProof(
self.id,
));
}
let commitment = self.commitment_to_randomness.take().unwrap();
let responses = commitment.response(self.witnesses.as_ref().unwrap(), challenge)?;
Ok(PedersenCommitmentProof::new(commitment.t, responses))
}
pub fn verify_proof_contribution<E: PairingEngine>(
&self,
challenge: &G::ScalarField,
proof: &StatementProof<E, G>,
) -> Result<(), ProofSystemError> {
match proof {
StatementProof::PedersenCommitment(p) => {
self.verify_proof_contribution_as_struct(challenge, p)
}
_ => Err(ProofSystemError::ProofIncompatibleWithSchnorrProtocol),
}
}
pub fn verify_proof_contribution_as_struct(
&self,
challenge: &G::ScalarField,
proof: &PedersenCommitmentProof<G>,
) -> Result<(), ProofSystemError> {
proof
.response
.is_valid(self.commitment_key, &self.commitment, &proof.t, challenge)
.map_err(|e| e.into())
}
pub fn compute_challenge_contribution<W: Write>(
bases: &[G],
y: &G,
t: &G,
mut writer: W,
) -> Result<(), ProofSystemError> {
bases.serialize_unchecked(&mut writer)?;
y.serialize_unchecked(&mut writer)?;
t.serialize_unchecked(writer)?;
Ok(())
}
}
impl<'a, G: AffineCurve> Zeroize for SchnorrProtocol<'a, G> {
fn zeroize(&mut self) {
self.commitment_to_randomness.as_mut().map(|c| c.zeroize());
self.witnesses
.as_mut()
.map(|w| cfg_iter_mut!(w).for_each(|v| v.zeroize()));
}
}
impl<'a, G: AffineCurve> Drop for SchnorrProtocol<'a, G> {
fn drop(&mut self) {
self.zeroize();
}
}