plonky2/src/fri/proof.rs

use serde::{Deserialize, Serialize};

use crate::field::extension_field::target::ExtensionTarget;
use crate::field::extension_field::Extendable;
use crate::field::field_types::Field;
use crate::gadgets::polynomial::PolynomialCoeffsExtTarget;
use crate::hash::hash_types::{HashOut, HashOutTarget};
use crate::hash::merkle_proofs::{MerkleProof, MerkleProofTarget};
use crate::iop::target::Target;
use crate::plonk::plonk_common::PolynomialsIndexBlinding;
use crate::polynomial::polynomial::PolynomialCoeffs;

/// Evaluations and Merkle proof produced by the prover in a FRI query step.
#[derive(Serialize, Deserialize, Clone, Debug)]
#[serde(bound = "")]
pub struct FriQueryStep<F: Extendable<D>, const D: usize> {
    pub evals: Vec<F::Extension>,
    pub merkle_proof: MerkleProof<F>,
}

#[derive(Clone)]
pub struct FriQueryStepTarget<const D: usize> {
    pub evals: Vec<ExtensionTarget<D>>,
    pub merkle_proof: MerkleProofTarget,
}

/// Evaluations and Merkle proofs of the original set of polynomials,
/// before they are combined into a composition polynomial.
#[derive(Serialize, Deserialize, Clone, Debug)]
#[serde(bound = "")]
pub struct FriInitialTreeProof<F: Field> {
    pub evals_proofs: Vec<(Vec<F>, MerkleProof<F>)>,
}

impl<F: Field> FriInitialTreeProof<F> {
    pub(crate) fn unsalted_evals(
        &self,
        polynomials: PolynomialsIndexBlinding,
        zero_knowledge: bool,
    ) -> &[F] {
        let evals = &self.evals_proofs[polynomials.index].0;
        &evals[..evals.len() - polynomials.salt_size(zero_knowledge)]
    }
}

#[derive(Clone)]
pub struct FriInitialTreeProofTarget {
    pub evals_proofs: Vec<(Vec<Target>, MerkleProofTarget)>,
}

impl FriInitialTreeProofTarget {
    pub(crate) fn unsalted_evals(
        &self,
        polynomials: PolynomialsIndexBlinding,
        zero_knowledge: bool,
    ) -> &[Target] {
        let evals = &self.evals_proofs[polynomials.index].0;
        &evals[..evals.len() - polynomials.salt_size(zero_knowledge)]
    }
}

/// Proof for a FRI query round.
#[derive(Serialize, Deserialize, Clone, Debug)]
#[serde(bound = "")]
pub struct FriQueryRound<F: Extendable<D>, const D: usize> {
    pub initial_trees_proof: FriInitialTreeProof<F>,
    pub steps: Vec<FriQueryStep<F, D>>,
}

#[derive(Clone)]
pub struct FriQueryRoundTarget<const D: usize> {
    pub initial_trees_proof: FriInitialTreeProofTarget,
    pub steps: Vec<FriQueryStepTarget<D>>,
}

#[derive(Serialize, Deserialize, Clone, Debug)]
#[serde(bound = "")]
pub struct FriProof<F: Extendable<D>, const D: usize> {
    /// A Merkle root for each reduced polynomial in the commit phase.
    pub commit_phase_merkle_roots: Vec<HashOut<F>>,
    /// Query rounds proofs
    pub query_round_proofs: Vec<FriQueryRound<F, D>>,
    /// The final polynomial in coefficient form.
    pub final_poly: PolynomialCoeffs<F::Extension>,
    /// Witness showing that the prover did PoW.
    pub pow_witness: F,
}

pub struct FriProofTarget<const D: usize> {
    pub commit_phase_merkle_roots: Vec<HashOutTarget>,
    pub query_round_proofs: Vec<FriQueryRoundTarget<D>>,
    pub final_poly: PolynomialCoeffsExtTarget<D>,
    pub pow_witness: Target,
}