Fix/statement absorption (#21)

Co-authored-by: GOURIOU Lénaïck <[email protected]>

Author: Chausseaumoine

src/composition.rs

@@ -636,19 +636,17 @@ where
     G: Group + GroupEncoding,
     C: Codec<Challenge = ProtocolChallenge<G>>,
 {
-    fn absorb_statement_and_commitment(&self, codec: &mut C, commitment: &Self::Commitment) {
+    fn absorb_commitment(&self, codec: &mut C, commitment: &Self::Commitment) {
         match (self, commitment) {
-            (Protocol::Simple(p), ProtocolCommitment::Simple(c)) => {
-                p.absorb_statement_and_commitment(codec, c)
-            }
+            (Protocol::Simple(p), ProtocolCommitment::Simple(c)) => p.absorb_commitment(codec, c),
             (Protocol::And(ps), ProtocolCommitment::And(cs)) => {
                 for (i, p) in ps.iter().enumerate() {
-                    p.absorb_statement_and_commitment(codec, &cs[i]);
+                    p.absorb_commitment(codec, &cs[i]);
                 }
             }
             (Protocol::Or(ps), ProtocolCommitment::Or(cs)) => {
                 for (i, p) in ps.iter().enumerate() {
-                    p.absorb_statement_and_commitment(codec, &cs[i]);
+                    p.absorb_commitment(codec, &cs[i]);
                 }
             }
             _ => panic!(),

src/fiat_shamir.rs

@@ -28,7 +28,7 @@ use rand::{CryptoRng, RngCore};
 /// # Type Parameters
 /// - `C`: the codec used for encoding/decoding messages to/from the IP space.
 pub trait FiatShamir<C: Codec>: SigmaProtocol {
-    fn absorb_statement_and_commitment(&self, codec: &mut C, commitment: &Self::Commitment);
+    fn absorb_commitment(&self, codec: &mut C, commitment: &Self::Commitment);
 
     fn get_challenge(&self, codec: &mut C) -> Result<Self::Challenge, Error>;
 }
@@ -109,8 +109,7 @@ where
 
         let (commitment, prover_state) = self.sigmap.prover_commit(witness, rng)?;
         // Fiat Shamir challenge
-        self.sigmap
-            .absorb_statement_and_commitment(&mut codec, &commitment);
+        self.sigmap.absorb_commitment(&mut codec, &commitment);
         let challenge = self.sigmap.get_challenge(&mut codec)?;
         // Prover's response
         let response = self.sigmap.prover_response(prover_state, &challenge)?;
@@ -143,8 +142,7 @@ where
         let mut codec = self.hash_state.clone();
 
         // Recompute the challenge
-        self.sigmap
-            .absorb_statement_and_commitment(&mut codec, commitment);
+        self.sigmap.absorb_commitment(&mut codec, commitment);
         let expected_challenge = self.sigmap.get_challenge(&mut codec)?;
         // Verification of the proof
         match *challenge == expected_challenge {
@@ -194,8 +192,7 @@ where
         let mut codec = self.hash_state.clone();
 
         // Recompute the challenge
-        self.sigmap
-            .absorb_statement_and_commitment(&mut codec, &commitment);
+        self.sigmap.absorb_commitment(&mut codec, &commitment);
         let challenge = self.sigmap.get_challenge(&mut codec)?;
         // Verification of the proof
         self.sigmap.verifier(&commitment, &challenge, &response)

src/schnorr_protocol.rs

@@ -438,15 +438,13 @@ where
     /// Absorbs statement and commitment into the codec.
     ///
     /// # Parameters
-    /// - `codec`: the Codec that absorbs commitments.
-    /// - `commitment`: a commitment of [`SchnorrProtocol`].
-    fn absorb_statement_and_commitment(&self, codec: &mut C, commitment: &Self::Commitment) {
-        let mut data = self.0.label();
-
+    /// - `codec`: the Codec that absorbs commitments
+    /// - `commitment`: a commitment of SchnorrProtocol
+    fn absorb_commitment(&self, codec: &mut C, commitment: &Self::Commitment) {
+        let mut data = Vec::new();
         for commit in commitment {
             data.extend_from_slice(commit.to_bytes().as_ref());
         }
-
         codec.prover_message(&data);
     }
 

src/tests/spec/custom_schnorr_protocol.rs

@@ -156,7 +156,7 @@ where
     C: Codec<Challenge = <G as Group>::Scalar>,
     G: SRandom + GroupEncoding,
 {
-    fn absorb_statement_and_commitment(&self, codec: &mut C, commitment: &Self::Commitment) {
+    fn absorb_commitment(&self, codec: &mut C, commitment: &Self::Commitment) {
         let mut data = Vec::new();
         for commit in commitment {
             data.extend_from_slice(commit.to_bytes().as_ref());