Implemented Mova folding scheme

folding-schemes/src/folding/mod.rs

@@ -1,4 +1,5 @@
 pub mod circuits;
 pub mod hypernova;
+pub mod mova;
 pub mod nova;
 pub mod protogalaxy;

folding-schemes/src/folding/mova/mod.rs

@@ -0,0 +1,127 @@
+use crate::commitment::CommitmentScheme;
+use crate::transcript::AbsorbNonNative;
+use crate::utils::mle::dense_vec_to_dense_mle;
+use crate::utils::vec::is_zero_vec;
+use crate::Error;
+use ark_crypto_primitives::sponge::Absorb;
+use ark_ec::CurveGroup;
+use ark_ff::PrimeField;
+use ark_poly::MultilinearExtension;
+use ark_serialize::{CanonicalDeserialize, CanonicalSerialize};
+use ark_std::rand::RngCore;
+
+use ark_std::{log2, One, UniformRand, Zero};
+
+/// Implements the scheme described in [Mova](https://eprint.iacr.org/2024/1220.pdf)
+mod nifs;
+mod pointvsline;
+mod traits;
+
+#[derive(Debug, Clone, Eq, PartialEq, CanonicalSerialize, CanonicalDeserialize)]
+pub struct CommittedInstance<C: CurveGroup> {
+    // Random evaluation point for the E
+    pub rE: Vec<C::ScalarField>,
+    // MLE of E
+    pub mleE: C::ScalarField,
+    pub u: C::ScalarField,
+    pub cmW: C,
+    pub x: Vec<C::ScalarField>,
+}
+#[derive(Debug, Clone, Eq, PartialEq, CanonicalSerialize, CanonicalDeserialize)]
+pub struct Witness<C: CurveGroup> {
+    pub E: Vec<C::ScalarField>,
+    pub W: Vec<C::ScalarField>,
+    pub rW: C::ScalarField,
+}
+
+#[derive(Debug, Clone, Eq, PartialEq, CanonicalSerialize, CanonicalDeserialize)]
+pub struct InstanceWitness<C: CurveGroup> {
+    pub ci: CommittedInstance<C>,
+    pub w: Witness<C>,
+}
+
+impl<C: CurveGroup> Witness<C> {
+    pub fn new<const H: bool>(w: Vec<C::ScalarField>, e_len: usize, mut rng: impl RngCore) -> Self {
+        let rW = if H {
+            C::ScalarField::rand(&mut rng)
+        } else {
+            C::ScalarField::zero()
+        };
+
+        Self {
+            E: vec![C::ScalarField::zero(); e_len],
+            W: w,
+            rW,
+        }
+    }
+
+    pub fn dummy(w_len: usize, e_len: usize) -> Self {
+        let rW = C::ScalarField::zero();
+        let w = vec![C::ScalarField::zero(); w_len];
+
+        Self {
+            E: vec![C::ScalarField::zero(); e_len],
+            W: w,
+            rW,
+        }
+    }
+
+    pub fn commit<CS: CommitmentScheme<C>>(
+        &self,
+        params: &CS::ProverParams,
+        x: Vec<C::ScalarField>,
+        rE: Vec<C::ScalarField>,
+    ) -> Result<CommittedInstance<C>, Error> {
+        let mut mleE = C::ScalarField::zero();
+        if !is_zero_vec::<C::ScalarField>(&self.E) {
+            let E = dense_vec_to_dense_mle(log2(self.E.len()) as usize, &self.E);
+            mleE = E.evaluate(&rE).ok_or(Error::NotExpectedLength(
+                rE.len(),
+                log2(self.E.len()) as usize,
+            ))?;
+        }
+        let cmW = CS::commit(params, &self.W, &self.rW)?;
+        Ok(CommittedInstance {
+            rE,
+            mleE,
+            u: C::ScalarField::one(),
+            cmW,
+            x,
+        })
+    }
+}
+
+impl<C: CurveGroup> CommittedInstance<C> {
+    pub fn dummy(io_len: usize) -> Self {
+        Self {
+            rE: vec![C::ScalarField::zero(); io_len],
+            mleE: C::ScalarField::zero(),
+            u: C::ScalarField::zero(),
+            cmW: C::zero(),
+            x: vec![C::ScalarField::zero(); io_len],
+        }
+    }
+}
+
+impl<C: CurveGroup> Absorb for CommittedInstance<C>
+where
+    C::ScalarField: Absorb,
+{
+    fn to_sponge_bytes(&self, _dest: &mut Vec<u8>) {
+        // This is never called
+        unimplemented!()
+    }
+
+    fn to_sponge_field_elements<F: PrimeField>(&self, dest: &mut Vec<F>) {
+        self.u.to_sponge_field_elements(dest);
+        self.x.to_sponge_field_elements(dest);
+        self.rE.to_sponge_field_elements(dest);
+        self.mleE.to_sponge_field_elements(dest);
+        // We cannot call `to_native_sponge_field_elements(dest)` directly, as
+        // `to_native_sponge_field_elements` needs `F` to be `C::ScalarField`,
+        // but here `F` is a generic `PrimeField`.
+        self.cmW
+            .to_native_sponge_field_elements_as_vec()
+            .to_sponge_field_elements(dest);
+    }
+}