p3_commit/adapters/
extension_mmcs.rs

1use alloc::vec::Vec;
2use core::marker::PhantomData;
3use core::ops::Deref;
4
5use p3_field::{ExtensionField, Field};
6use p3_matrix::extension::FlatMatrixView;
7use p3_matrix::{Dimensions, Matrix};
8
9use crate::{BatchOpening, BatchOpeningRef, Mmcs};
10
11/// A wrapper to lift an MMCS from a base field `F` to an extension field `EF`.
12///
13/// `ExtensionMmcs` allows committing to and opening matrices over an extension field by internally
14/// using an MMCS defined on the base field. It works by flattening each extension field element
15/// into its base field coordinates for commitment, and then reconstructing them on opening.
16#[derive(Clone, Debug)]
17pub struct ExtensionMmcs<F, EF, InnerMmcs> {
18    /// The inner MMCS instance used to handle commitments at the base field level.
19    pub(crate) inner: InnerMmcs,
20
21    pub(crate) _phantom: PhantomData<(F, EF)>,
22}
23
24impl<F, EF, InnerMmcs> ExtensionMmcs<F, EF, InnerMmcs> {
25    pub const fn new(inner: InnerMmcs) -> Self {
26        Self {
27            inner,
28            _phantom: PhantomData,
29        }
30    }
31}
32
33impl<F, EF, InnerMmcs> Mmcs<EF> for ExtensionMmcs<F, EF, InnerMmcs>
34where
35    F: Field,
36    EF: ExtensionField<F>,
37    InnerMmcs: Mmcs<F>,
38{
39    type ProverData<M> = InnerMmcs::ProverData<FlatMatrixView<F, EF, M>>;
40    type Commitment = InnerMmcs::Commitment;
41    type Proof = InnerMmcs::Proof;
42    type Error = InnerMmcs::Error;
43
44    fn commit<M: Matrix<EF>>(&self, inputs: Vec<M>) -> (Self::Commitment, Self::ProverData<M>) {
45        self.inner
46            .commit(inputs.into_iter().map(FlatMatrixView::new).collect())
47    }
48
49    fn open_batch<M: Matrix<EF>>(
50        &self,
51        index: usize,
52        prover_data: &Self::ProverData<M>,
53    ) -> BatchOpening<EF, Self> {
54        let (inner_opened_values, inner_proof) = self.inner.open_batch(index, prover_data).unpack();
55        let opened_ext_values = inner_opened_values
56            .into_iter()
57            .map(EF::reconstitute_from_base)
58            .collect();
59        BatchOpening::new(opened_ext_values, inner_proof)
60    }
61
62    fn get_matrices<'a, M: Matrix<EF>>(&self, prover_data: &'a Self::ProverData<M>) -> Vec<&'a M> {
63        self.inner
64            .get_matrices(prover_data)
65            .into_iter()
66            .map(|mat| mat.deref())
67            .collect()
68    }
69
70    fn verify_batch(
71        &self,
72        commit: &Self::Commitment,
73        dimensions: &[Dimensions],
74        index: usize,
75        batch_opening: BatchOpeningRef<'_, EF, Self>,
76    ) -> Result<(), Self::Error> {
77        let opened_base_values: Vec<Vec<F>> = batch_opening
78            .opened_values
79            .iter()
80            .cloned()
81            .map(EF::flatten_to_base)
82            .collect();
83        let base_dimensions = dimensions
84            .iter()
85            .map(|dim| Dimensions {
86                width: dim.width * EF::DIMENSION,
87                height: dim.height,
88            })
89            .collect::<Vec<_>>();
90        self.inner.verify_batch(
91            commit,
92            &base_dimensions,
93            index,
94            BatchOpeningRef::new(&opened_base_values, batch_opening.opening_proof),
95        )
96    }
97}
p3_commit/adapters/extension_mmcs.rs

p3_commit/adapters/
extension_mmcs.rs
