renamed variable and simplified code

Author: damrobi

mithril-stm/src/signature_scheme/schnorr_signature/signature.rs

@@ -55,13 +55,13 @@ impl SchnorrSignature {
         let msg_hash_point = ProjectivePoint::hash_to_projective_point(msg)?;
 
         // Computing random_point_1_recomputed = response *  H(msg) + challenge * commitment_point
-        let challenge_scalar = ScalarFieldElement::from_base_field(&self.challenge)?;
+        let challenge_as_scalar = ScalarFieldElement::from_base_field(&self.challenge)?;
         let random_point_1_recomputed =
-            self.response * msg_hash_point + challenge_scalar * self.commitment_point;
+            self.response * msg_hash_point + challenge_as_scalar * self.commitment_point;
 
         // Computing random_point_2_recomputed = response * prime_order_generator_point + challenge * vk
         let random_point_2_recomputed =
-            self.response * prime_order_generator_point + challenge_scalar * verification_key.0;
+            self.response * prime_order_generator_point + challenge_as_scalar * verification_key.0;
 
         // Since the hash function takes as input scalar elements
         // We need to convert the EC points to their coordinates

mithril-stm/src/signature_scheme/schnorr_signature/signing_key.rs

@@ -82,8 +82,7 @@ impl SchnorrSigningKey {
         .collect();
 
         let challenge = compute_poseidon_digest(&points_coordinates);
-        let challenge_as_scalar = ScalarFieldElement::from_base_field(&challenge)?;
-        let challenge_times_sk = challenge_as_scalar * self.0;
+        let challenge_times_sk = ScalarFieldElement::from_base_field(&challenge)? * self.0;
         let response = random_scalar - challenge_times_sk;
 
         Ok(SchnorrSignature {