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//! Implementation of permutation argument.
use super::circuit::{Any, Column};
use crate::{
poly::{Coeff, ExtendedLagrangeCoeff, LagrangeCoeff, Polynomial},
utils::{
helpers::{polynomial_slice_byte_length, read_polynomial_vec, write_polynomial_slice},
SerdeFormat,
},
};
pub(crate) mod keygen;
pub(crate) mod prover;
pub(crate) mod verifier;
use std::io;
use ff::{PrimeField, WithSmallOrderMulGroup};
pub use keygen::Assembly;
use midnight_curves::serde::SerdeObject;
use crate::{
plonk::permutation::keygen::compute_polys_and_cosets,
poly::{commitment::PolynomialCommitmentScheme, EvaluationDomain},
utils::helpers::{byte_length, ProcessedSerdeObject},
};
/// A permutation argument.
#[derive(Debug, Clone)]
pub struct Argument {
/// A sequence of columns involved in the argument.
pub columns: Vec<Column<Any>>,
}
impl Argument {
pub(crate) fn new() -> Self {
Argument { columns: vec![] }
}
/// Returns the minimum circuit degree required by the permutation argument.
/// The argument may use larger degree gates depending on the actual
/// circuit's degree and how many columns are involved in the permutation.
pub(crate) fn required_degree(&self) -> usize {
// degree 2:
// l_0(X) * (1 - z(X)) = 0
//
// We will fit as many polynomials p_i(X) as possible
// into the required degree of the circuit, so the
// following will not affect the required degree of
// this middleware.
//
// (1 - (l_last(X) + l_blind(X))) * (
// z(\omega X) \prod (p(X) + \beta s_i(X) + \gamma)
// - z(X) \prod (p(X) + \delta^i \beta X + \gamma)
// )
//
// On the first sets of columns, except the first
// set, we will do
//
// l_0(X) * (z(X) - z'(\omega^(last) X)) = 0
//
// where z'(X) is the permutation for the previous set
// of columns.
//
// On the final set of columns, we will do
//
// degree 3:
// l_last(X) * (z'(X)^2 - z'(X)) = 0
//
// which will allow the last value to be zero to
// ensure the argument is perfectly complete.
// There are constraints of degree 3 regardless of the
// number of columns involved.
3
}
pub(crate) fn add_column(&mut self, column: Column<Any>) {
if !self.columns.contains(&column) {
self.columns.push(column);
}
}
/// Returns columns that participate on the permutation argument.
pub fn get_columns(&self) -> Vec<Column<Any>> {
self.columns.clone()
}
}
/// The verifying key for a single permutation argument.
#[derive(Clone, Debug)]
pub struct VerifyingKey<F: PrimeField, CS: PolynomialCommitmentScheme<F>> {
commitments: Vec<CS::Commitment>,
}
impl<F: PrimeField, CS: PolynomialCommitmentScheme<F>> VerifyingKey<F, CS> {
/// Returns the (permutation argument) commitments of the verifying key.
pub fn commitments(&self) -> &Vec<CS::Commitment> {
&self.commitments
}
pub(crate) fn write<W: io::Write>(&self, writer: &mut W, format: SerdeFormat) -> io::Result<()>
where
CS::Commitment: ProcessedSerdeObject,
{
for commitment in &self.commitments {
commitment.write(writer, format)?;
}
Ok(())
}
pub(crate) fn read<R: io::Read>(
reader: &mut R,
argument: &Argument,
format: SerdeFormat,
) -> io::Result<Self>
where
CS::Commitment: ProcessedSerdeObject,
{
let commitments = (0..argument.columns.len())
.map(|_| CS::Commitment::read(reader, format))
.collect::<Result<Vec<_>, _>>()?;
Ok(VerifyingKey { commitments })
}
pub(crate) fn bytes_length(&self, format: SerdeFormat) -> usize
where
CS::Commitment: ProcessedSerdeObject,
{
self.commitments.len() * byte_length::<CS::Commitment>(format)
}
}
/// The proving key for a single permutation argument.
#[derive(Clone, Debug)]
pub(crate) struct ProvingKey<F: PrimeField> {
pub(crate) permutations: Vec<Polynomial<F, LagrangeCoeff>>,
pub(crate) polys: Vec<Polynomial<F, Coeff>>,
pub(crate) cosets: Vec<Polynomial<F, ExtendedLagrangeCoeff>>,
}
impl<F: WithSmallOrderMulGroup<3> + SerdeObject> ProvingKey<F> {
/// Reads proving key for a single permutation argument from buffer using
/// `Polynomial::read`.
pub(super) fn read<R: io::Read>(
reader: &mut R,
format: SerdeFormat,
domain: &EvaluationDomain<F>,
p: &Argument,
) -> io::Result<Self> {
let permutations = read_polynomial_vec(reader, format)?;
let (polys, cosets) = compute_polys_and_cosets::<F>(domain, p, &permutations);
Ok(ProvingKey {
permutations,
polys,
cosets,
})
}
/// Writes proving key for a single permutation argument to buffer using
/// `Polynomial::write`.
pub(super) fn write<W: io::Write>(&self, writer: &mut W) -> io::Result<()> {
write_polynomial_slice(&self.permutations, writer)?;
Ok(())
}
}
impl<F: PrimeField> ProvingKey<F> {
/// Gets the total number of bytes in the serialization of `self`
pub(super) fn bytes_length(&self) -> usize {
polynomial_slice_byte_length(&self.permutations)
+ polynomial_slice_byte_length(&self.polys)
+ polynomial_slice_byte_length(&self.cosets)
}
}