Modified the GroupSerialisation trait to remove the dependency on a generic Group G and tested implementations for bls12_381

Author: nougzarm

src/toolbox/sigma/group_serialisation.rs

@@ -5,16 +5,12 @@ use bls12_381::{G1Affine, G1Projective, Scalar as BlsScalar};
 use ff::PrimeField;
 use super::r#trait::GroupSerialisation;
 
-pub struct RistrettoSerialisation;
-
-impl GroupSerialisation<RistrettoPoint> for RistrettoSerialisation {
-    type Scalar = RistrettoScalar;
-
-    fn serialize_element(point: &RistrettoPoint) -> Vec<u8> {
+impl GroupSerialisation for RistrettoPoint {
+    fn serialize_element(point: &Self) -> Vec<u8> {
         point.compress().to_bytes().to_vec()
     }
 
-    fn deserialize_element(bytes: &[u8]) -> Option<RistrettoPoint> {
+    fn deserialize_element(bytes: &[u8]) -> Option<Self> {
         let point_size = 32;
         if bytes.len() != point_size {
             return None;
@@ -38,11 +34,8 @@ impl GroupSerialisation<RistrettoPoint> for RistrettoSerialisation {
     }
 }
 
-pub struct Bls12381Serialisation;
-
-impl GroupSerialisation<G1Projective> for Bls12381Serialisation {
-    type Scalar = BlsScalar;
 
+impl GroupSerialisation for G1Projective {
     fn serialize_element(point: &G1Projective) -> Vec<u8> {
         let affine = G1Affine::from(point);
         affine.to_compressed().as_ref().to_vec()
@@ -54,8 +47,14 @@ impl GroupSerialisation<G1Projective> for Bls12381Serialisation {
         }
         let mut buf = [0u8; 48];
         buf.copy_from_slice(bytes);
-        let affine = G1Affine::from_compressed(&buf).into_option()?;
-        Some(G1Projective::from(&affine))
+        let affine_ctoption = G1Affine::from_compressed(&buf);
+        if affine_ctoption.is_some().into() {
+            let affine = affine_ctoption.unwrap();
+            Some(G1Projective::from(&affine))
+        }
+        else {
+            None
+        }
     }
 
     fn serialize_scalar(scalar: &Self::Scalar) -> Vec<u8> {
@@ -64,6 +63,12 @@ impl GroupSerialisation<G1Projective> for Bls12381Serialisation {
 
     fn deserialize_scalar(bytes: &[u8]) -> Option<Self::Scalar> {
         let repr = bytes.try_into().ok()?;
-        BlsScalar::from_repr(repr).into_option()
+        let result_ctoption = BlsScalar::from_repr(repr);
+        if result_ctoption.is_some().into() {
+            Some(result_ctoption.unwrap())
+        }
+        else {
+            None
+        }
     }    
 }

src/toolbox/sigma/schnorr_proof.rs

@@ -14,14 +14,12 @@ use super::r#trait::GroupSerialisation;
 /// A Schnorr protocol proving knowledge some discrete logarithm relation.
 ///
 /// The specific proof instance is defined by a [`GroupMorphismPreimage`] over a group `G`.
-pub struct SchnorrProof<G, S>
+pub struct SchnorrProof<G>
 where 
-    G: Group + GroupEncoding,
-    S: GroupSerialisation<G, Scalar = G::Scalar>
+    G: Group + GroupEncoding + GroupSerialisation
 {
     /// The public instance and its associated group morphism.
-    pub morphismp: GroupMorphismPreimage<G>,
-    _marker: std::marker::PhantomData<S>
+    pub morphismp: GroupMorphismPreimage<G>
 }
 
 /// Internal prover state during the protocol execution: (random nonce, witness)
@@ -32,11 +30,10 @@ pub struct SchnorrState<S> {
     pub witness: Vec<S>,
 }
 
-impl<G, S> SigmaProtocol for SchnorrProof<G,S>
+impl<G> SigmaProtocol for SchnorrProof<G>
 where
-    G: Group + GroupEncoding, 
+    G: Group + GroupEncoding + GroupSerialisation, 
     G::Scalar: Field + Clone,
-    S: GroupSerialisation<G, Scalar = G::Scalar>
 {
     type Commitment = Vec<G>;
     type ProverState = (Vec<<G as Group>::Scalar>, Vec<<G as Group>::Scalar>);
@@ -105,12 +102,12 @@ where
 
         // Serialize commitments
         for commit in commitment.iter().take(point_nb) {
-            bytes.extend_from_slice(&S::serialize_element(commit));
+            bytes.extend_from_slice(&G::serialize_element(commit));
         }
 
         // Serialize responses
         for response in response.iter().take(scalar_nb) {
-            bytes.extend_from_slice(&S::serialize_scalar(response));
+            bytes.extend_from_slice(&G::serialize_scalar(response));
         }
         bytes
     }
@@ -139,7 +136,7 @@ where
             let end = start + point_size;
 
             let slice = &data[start..end];
-            let elem = S::deserialize_element(slice)?;
+            let elem = G::deserialize_element(slice)?;
             commitments.push(elem);
         }
 
@@ -148,7 +145,7 @@ where
             let end = start + scalar_size;
 
             let slice = &data[start..end];
-            let scalar = S::deserialize_scalar(slice)?;
+            let scalar = G::deserialize_scalar(slice)?;
             responses.push(scalar);
         }
 

src/toolbox/sigma/trait.rs

@@ -2,7 +2,8 @@
 //!
 //! This module defines the `SigmaProtocol` trait, a generic interface for 3-message Sigma protocols.
 
-use group::Group;
+use ff::PrimeField;
+use group::{Group, GroupEncoding};
 use rand::{Rng, CryptoRng};
 use crate::ProofError;
 
@@ -123,16 +124,13 @@ pub trait SigmaProtocolSimulator: SigmaProtocol {
     }
 }
 
-pub trait GroupSerialisation<G>
+pub trait GroupSerialisation: Group + GroupEncoding
 where 
-    G: Group,
+    Self::Scalar: PrimeField, 
 {
-    type Scalar: ff::PrimeField;
-
-    fn serialize_element(point: &G) -> Vec<u8>;
-    fn deserialize_element(bytes: &[u8]) -> Option<G>;
+    fn serialize_element(point: &Self) -> Vec<u8>;
+    fn deserialize_element(bytes: &[u8]) -> Option<Self>;
 
     fn serialize_scalar(scalar: &Self::Scalar) -> Vec<u8>;
     fn deserialize_scalar(bytes: &[u8]) -> Option<Self::Scalar>;
-
 }

tests/sage_proofs.rs

@@ -1,6 +1,6 @@
+use bls12_381::G1Projective;
 use rand::{{Rng, CryptoRng}, rngs::OsRng};
 use group::{Group, GroupEncoding, ff::Field};
-use curve25519_dalek::ristretto::RistrettoPoint;
 
 use sigma_rs::toolbox::sigma::{
     GroupMorphismPreimage,
@@ -9,7 +9,7 @@ use sigma_rs::toolbox::sigma::{
     NISigmaProtocol,
 };
 
-type G = RistrettoPoint;
+type G = G1Projective;
 
 fn msm_pr<G: Group>(scalars: &[G::Scalar], bases: &[G]) -> G {
     let mut acc = G::identity();