w3f-pcs 0.0.6

Collection of tools for augmenting polynomial commitment schemes
Documentation 
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use ark_ff::PrimeField;
use ark_poly::{DenseUVPolynomial, Polynomial};
use ark_serialize::*;
use ark_std::collections::BTreeSet;
use ark_std::marker::PhantomData;
use ark_std::vec::Vec;

use crate::aggregation::multiple::{
    aggregate_claims, aggregate_polys, group_by_commitment, Transcript,
};
use crate::pcs::PCS;
use crate::Poly;

pub struct Shplonk<F: PrimeField, CS: PCS<F>> {
    _field: PhantomData<F>,
    _pcs: PhantomData<CS>,
}

#[derive(Clone, Debug, CanonicalSerialize, CanonicalDeserialize)]
pub struct AggregateProof<F: PrimeField, CS: PCS<F>> {
    agg_proof: CS::C,
    opening_proof: CS::Proof,
}

impl<F: PrimeField, CS: PCS<F>> Shplonk<F, CS> {
    pub fn open_many<T: Transcript<F, CS>>(
        ck: &CS::CK,
        fs: &[Poly<F>],
        xss: &[BTreeSet<F>],
        transcript: &mut T,
    ) -> AggregateProof<F, CS> {
        let (agg_poly, zeta, agg_proof) = aggregate_polys::<F, CS, T>(ck, fs, xss, transcript);
        assert!(agg_poly.evaluate(&zeta).is_zero());
        let opening_proof = CS::open(ck, &agg_poly, zeta).unwrap();
        AggregateProof {
            agg_proof,
            opening_proof,
        }
    }

    pub fn verify_many<T: Transcript<F, CS>>(
        vk: &CS::VK,
        fcs: &[CS::C],
        proof: AggregateProof<F, CS>,
        xss: &Vec<Vec<F>>,
        yss: &Vec<Vec<F>>,
        transcript: &mut T,
    ) -> bool {
        let AggregateProof {
            agg_proof,
            opening_proof,
        } = proof;
        let onec = CS::commit(
            &vk.clone().into(),
            &Poly::from_coefficients_slice(&[F::one()]),
        )
        .unwrap();
        let claims = group_by_commitment(fcs, xss, yss);
        let agg_claim = aggregate_claims::<F, CS, T>(claims, &agg_proof, &onec, transcript);
        CS::verify(
            vk,
            agg_claim.c,
            agg_claim.xs[0],
            agg_claim.ys[0],
            opening_proof,
        )
        .is_ok()
    }
}

#[cfg(test)]
pub(crate) mod tests {
    use ark_std::iter::FromIterator;
    use ark_std::rand::Rng;
    use ark_std::test_rng;

    use crate::pcs::IdentityCommitment;
    use crate::pcs::{Commitment, PcsParams};
    use crate::tests::{TestField, TestKzg};
    use crate::Poly;

    use super::*;

    pub struct TestOpening<F: PrimeField, C: Commitment<F>> {
        pub fs: Vec<Poly<F>>,
        pub fcs: Vec<C>,
        pub xss: Vec<Vec<F>>,
        pub yss: Vec<Vec<F>>,
    }

    pub(crate) fn random_xss<R: Rng, F: PrimeField>(
        rng: &mut R,
        t: usize,     // number of polynomials
        max_m: usize, // maximal number of opening points per polynomial
    ) -> Vec<Vec<F>> {
        (0..t)
            .map(|_| {
                (0..rng.gen_range(1..max_m))
                    .map(|_| F::rand(rng))
                    .collect::<Vec<_>>()
            })
            .collect()
    }

    pub(crate) fn random_opening<R, F, CS>(
        rng: &mut R,
        ck: &CS::CK,
        d: usize,         // degree of polynomials
        t: usize,         // number of polynomials
        xss: Vec<Vec<F>>, // vecs of opening points per polynomial
    ) -> TestOpening<F, CS::C>
    where
        R: Rng,
        F: PrimeField,
        CS: PCS<F>,
    {
        // polynomials
        let fs: Vec<_> = (0..t).map(|_| Poly::<F>::rand(d, rng)).collect();
        // commitments
        let fcs: Vec<_> = fs.iter().map(|fi| CS::commit(&ck, fi).unwrap()).collect();

        // evaluations per polynomial
        let yss: Vec<_> = fs
            .iter()
            .zip(xss.iter())
            .map(|(f, xs)| xs.iter().map(|x| f.evaluate(x)).collect::<Vec<_>>())
            .collect();

        TestOpening { fs, fcs, xss, yss }
    }

    fn _test_shplonk<F: PrimeField, CS: PCS<F>>() {
        let rng = &mut test_rng();

        let d = 15; // degree of polynomials
        let t = 4; // number of polynomials
        let max_m = 3; // maximal number of opening points per polynomial

        let params = CS::setup(d, rng);

        let xss = random_xss(rng, t, max_m);
        let opening = random_opening::<_, _, CS>(rng, &params.ck(), d, t, xss);

        let sets_of_xss: Vec<BTreeSet<F>> = opening
            .xss
            .iter()
            .map(|xs| BTreeSet::from_iter(xs.iter().cloned()))
            .collect();

        let transcript = &mut (F::rand(rng), F::rand(rng));

        let proof =
            Shplonk::<F, CS>::open_many(&params.ck(), &opening.fs, &sets_of_xss, transcript);

        assert!(Shplonk::<F, CS>::verify_many(
            &params.vk(),
            &opening.fcs,
            proof,
            &opening.xss,
            &opening.yss,
            transcript
        ))
    }

    #[test]
    fn test_shplonk() {
        _test_shplonk::<TestField, IdentityCommitment>();
        _test_shplonk::<TestField, TestKzg>();
    }
}