refactor: GroupMorphismPreimage -> LinearRelation.

Author: mmaker

src/composition.rs

@@ -16,7 +16,7 @@ use crate::traits::CompactProtocol;
 use crate::{
     errors::Error,
     fiat_shamir::{FiatShamir, HasGroupMorphism},
-    group_morphism::GroupMorphismPreimage,
+    group_morphism::LinearRelation,
     group_serialization::{deserialize_scalar, serialize_scalar},
     schnorr_protocol::SchnorrProtocol,
     traits::{SigmaProtocol, SigmaProtocolSimulator},
@@ -44,11 +44,11 @@ where
     }
 }
 
-impl<G> From<GroupMorphismPreimage<G>> for Protocol<G>
+impl<G> From<LinearRelation<G>> for Protocol<G>
 where
     G: Group + GroupEncoding,
 {
-    fn from(value: GroupMorphismPreimage<G>) -> Self {
+    fn from(value: LinearRelation<G>) -> Self {
         Self::from(SchnorrProtocol::from(value))
     }
 }

src/group_morphism.rs

@@ -6,7 +6,7 @@
 //! It includes:
 //! - [`LinearCombination`]: a sparse representation of scalar multiplication relations
 //! - [`Morphism`]: a collection of linear combinations acting on group elements
-//! - [`GroupMorphismPreimage`]: a higher-level structure managing morphisms and their associated images
+//! - [`LinearRelation`]: a higher-level structure managing morphisms and their associated images
 
 use crate::errors::Error;
 use group::{Group, GroupEncoding};
@@ -275,7 +275,7 @@ impl<G: Group> Morphism<G> {
 /// - A list of group elements and linear equations (held in the [`Morphism`] field),
 /// - A list of [`GroupVar`] indices (`image`) that specify the expected output for each constraint.
 #[derive(Clone, Default, Debug)]
-pub struct GroupMorphismPreimage<G>
+pub struct LinearRelation<G>
 where
     G: Group + GroupEncoding,
 {
@@ -285,11 +285,11 @@ where
     pub image: Vec<GroupVar>,
 }
 
-impl<G> GroupMorphismPreimage<G>
+impl<G> LinearRelation<G>
 where
     G: Group + GroupEncoding,
 {
-    /// Create a new empty GroupMorphismPreimage.
+    /// Create a new empty [`LinearRelation`].
     pub fn new() -> Self {
         Self {
             morphism: Morphism::new(),
@@ -339,10 +339,10 @@ where
     ///
     /// # Example
     /// ```
-    /// # use sigma_rs::group_morphism::GroupMorphismPreimage;
+    /// # use sigma_rs::group_morphism::LinearRelation;
     /// use curve25519_dalek::RistrettoPoint as G;
     ///
-    /// let mut morphism = GroupMorphismPreimage::<G>::new();
+    /// let mut morphism = LinearRelation::<G>::new();
     /// let [var_x, var_y] = morphism.allocate_scalars();
     /// let vars = morphism.allocate_scalars::<10>();
     /// ```
@@ -367,10 +367,10 @@ where
     ///
     /// # Example
     /// ```
-    /// # use sigma_rs::group_morphism::GroupMorphismPreimage;
+    /// # use sigma_rs::group_morphism::LinearRelation;
     /// use curve25519_dalek::RistrettoPoint as G;
     ///
-    /// let mut morphism = GroupMorphismPreimage::<G>::new();
+    /// let mut morphism = LinearRelation::<G>::new();
     /// let [var_g, var_h] = morphism.allocate_elements();
     /// let vars = morphism.allocate_elements::<10>();
     /// ```
@@ -421,12 +421,10 @@ where
     /// # Returns
     ///
     /// Return `Ok` on success, and an error if unassigned elements prevent the image from being
-    /// computed. Modifies the group elements assigned in the [GroupMorphismPreimage].
+    /// computed. Modifies the group elements assigned in the [LinearRelation].
     pub fn compute_image(&mut self, scalars: &[<G as Group>::Scalar]) -> Result<(), Error> {
         if self.morphism.constraints.len() != self.image.len() {
-            panic!(
-                "invalid GroupMorphismPreimage: different number of constraints and image variables"
-            );
+            panic!("invalid LinearRelation: different number of constraints and image variables");
         }
 
         for (lc, lhs) in iter::zip(self.morphism.constraints.as_slice(), self.image.as_slice()) {

src/schnorr_protocol.rs

@@ -7,7 +7,7 @@
 use crate::codec::Codec;
 use crate::errors::Error;
 use crate::fiat_shamir::{FiatShamir, HasGroupMorphism};
-use crate::group_morphism::GroupMorphismPreimage;
+use crate::group_morphism::LinearRelation;
 use crate::{
     group_serialization::*,
     traits::{CompactProtocol, SigmaProtocol, SigmaProtocolSimulator},
@@ -20,12 +20,12 @@ use rand::{CryptoRng, RngCore};
 /// A Schnorr protocol proving knowledge of a witness for a linear group relation.
 ///
 /// This implementation generalizes Schnorr’s discrete logarithm proof by using
-/// a [`GroupMorphismPreimage`], representing an abstract linear relation over the group.
+/// a [`LinearRelation`], representing an abstract linear relation over the group.
 ///
 /// # Type Parameters
 /// - `G`: A cryptographic group implementing [`Group`] and [`GroupEncoding`].
 #[derive(Clone, Default, Debug)]
-pub struct SchnorrProtocol<G: Group + GroupEncoding>(pub GroupMorphismPreimage<G>);
+pub struct SchnorrProtocol<G: Group + GroupEncoding>(pub LinearRelation<G>);
 
 impl<G: Group + GroupEncoding> SchnorrProtocol<G> {
     pub fn scalars_nb(&self) -> usize {
@@ -37,11 +37,11 @@ impl<G: Group + GroupEncoding> SchnorrProtocol<G> {
     }
 }
 
-impl<G> From<GroupMorphismPreimage<G>> for SchnorrProtocol<G>
+impl<G> From<LinearRelation<G>> for SchnorrProtocol<G>
 where
     G: Group + GroupEncoding,
 {
-    fn from(value: GroupMorphismPreimage<G>) -> Self {
+    fn from(value: LinearRelation<G>) -> Self {
         Self(value)
     }
 }

src/tests/composition_protocol.rs renamed to src/tests/composition.rs

@@ -1,4 +1,4 @@
-mod composition_protocol;
-mod morphism_preimage;
+mod composition;
+mod relations;
 mod spec;
 pub mod test_utils;

src/tests/mod.rs

@@ -10,7 +10,7 @@ use crate::tests::test_utils::{
 use crate::{codec::ShakeCodec, schnorr_protocol::SchnorrProtocol};
 
 /// This part tests the functioning of morphisms
-/// as well as the implementation of GroupMorphismPreimage
+/// as well as the implementation of LinearRelation
 #[test]
 fn test_discrete_logarithm() {
     let mut rng = OsRng;

src/tests/morphism_preimage.rs renamed to src/tests/relations.rs

@@ -5,12 +5,12 @@ use rand::{CryptoRng, Rng};
 use crate::codec::Codec;
 use crate::errors::Error;
 use crate::fiat_shamir::FiatShamir;
-use crate::group_morphism::GroupMorphismPreimage;
+use crate::group_morphism::LinearRelation;
 use crate::group_serialization::*;
 use crate::tests::spec::random::SRandom;
 use crate::traits::SigmaProtocol;
 
-pub struct SchnorrProtocolCustom<G: SRandom + GroupEncoding>(pub GroupMorphismPreimage<G>);
+pub struct SchnorrProtocolCustom<G: SRandom + GroupEncoding>(pub LinearRelation<G>);
 
 impl<G: SRandom + GroupEncoding> SchnorrProtocolCustom<G> {
     pub fn witness_len(&self) -> usize {

src/tests/spec/custom_schnorr_protocol.rs

@@ -1,5 +1,5 @@
 mod bls12_381;
 mod custom_schnorr_protocol;
 mod random;
-mod test_vectors;
 mod rng;
+mod test_vectors;

src/tests/spec/mod.rs

@@ -2,14 +2,14 @@
 
 use group::{Group, GroupEncoding};
 
-use crate::group_morphism::{GroupMorphismPreimage, msm_pr};
+use crate::group_morphism::{LinearRelation, msm_pr};
 
 /// Morphism for knowledge of a discrete logarithm relative to a fixed basepoint.
 #[allow(non_snake_case)]
 pub fn discrete_logarithm<G: Group + GroupEncoding>(
     x: G::Scalar,
-) -> (GroupMorphismPreimage<G>, Vec<G::Scalar>) {
-    let mut morphismp: GroupMorphismPreimage<G> = GroupMorphismPreimage::new();
+) -> (LinearRelation<G>, Vec<G::Scalar>) {
+    let mut morphismp: LinearRelation<G> = LinearRelation::new();
 
     let var_x = morphismp.allocate_scalar();
     let var_G = morphismp.allocate_element();
@@ -27,11 +27,8 @@ pub fn discrete_logarithm<G: Group + GroupEncoding>(
 
 /// Morphism for knowledge of a discrete logarithm equality between two pairs.
 #[allow(non_snake_case)]
-pub fn dleq<G: Group + GroupEncoding>(
-    x: G::Scalar,
-    H: G,
-) -> (GroupMorphismPreimage<G>, Vec<G::Scalar>) {
-    let mut morphismp: GroupMorphismPreimage<G> = GroupMorphismPreimage::new();
+pub fn dleq<G: Group + GroupEncoding>(x: G::Scalar, H: G) -> (LinearRelation<G>, Vec<G::Scalar>) {
+    let mut morphismp: LinearRelation<G> = LinearRelation::new();
 
     let var_x = morphismp.allocate_scalar();
     let [var_G, var_H] = morphismp.allocate_elements();
@@ -56,8 +53,8 @@ pub fn pedersen_commitment<G: Group + GroupEncoding>(
     H: G,
     x: G::Scalar,
     r: G::Scalar,
-) -> (GroupMorphismPreimage<G>, Vec<G::Scalar>) {
-    let mut cs: GroupMorphismPreimage<G> = GroupMorphismPreimage::new();
+) -> (LinearRelation<G>, Vec<G::Scalar>) {
+    let mut cs: LinearRelation<G> = LinearRelation::new();
 
     let [var_x, var_r] = cs.allocate_scalars();
     let [var_G, var_H] = cs.allocate_elements();
@@ -79,8 +76,8 @@ pub fn pedersen_commitment<G: Group + GroupEncoding>(
 pub fn pedersen_commitment_dleq<G: Group + GroupEncoding>(
     generators: [G; 4],
     witness: [G::Scalar; 2],
-) -> (GroupMorphismPreimage<G>, Vec<G::Scalar>) {
-    let mut morphismp: GroupMorphismPreimage<G> = GroupMorphismPreimage::new();
+) -> (LinearRelation<G>, Vec<G::Scalar>) {
+    let mut morphismp: LinearRelation<G> = LinearRelation::new();
 
     let X = msm_pr::<G>(&witness, &[generators[0], generators[1]]);
     let Y = msm_pr::<G>(&witness, &[generators[2], generators[3]]);
@@ -112,8 +109,8 @@ pub fn bbs_blind_commitment_computation<G: Group + GroupEncoding>(
     [Q_2, J_1, J_2, J_3]: [G; 4],
     [msg_1, msg_2, msg_3]: [G::Scalar; 3],
     secret_prover_blind: G::Scalar,
-) -> (GroupMorphismPreimage<G>, Vec<G::Scalar>) {
-    let mut morphismp = GroupMorphismPreimage::new();
+) -> (LinearRelation<G>, Vec<G::Scalar>) {
+    let mut morphismp = LinearRelation::new();
 
     // these are computed before the proof in the specification
     let C = Q_2 * secret_prover_blind + J_1 * msg_1 + J_2 * msg_2 + J_3 * msg_3;