Proof checking functions now return type Return< , > to allow error handling

Author: nougzarm

src/toolbox/sigma/fiat_shamir.rs

@@ -45,12 +45,12 @@ where
         // Prouver's response
         let response = self.sigmap.prover_response(&prover_state, &challenge);
         // Local verification of the proof
-        assert!(self.sigmap.verifier(&commitment, &challenge, &response));
+        assert!(self.sigmap.verifier(&commitment, &challenge, &response) == Ok(()));
         self.sigmap.serialize_batchable(&commitment, &challenge, &response)
     }
 
     /// Verification of non-interactive proof
-    pub fn verify(&mut self, proof: &Vec<u8>) -> bool {
+    pub fn verify(&mut self, proof: &Vec<u8>) -> Result<(), ()> {
         self.hash_state = C::new(&self.domain_sep);
 
         let (commitment, response) = self.sigmap.deserialize_batchable(proof).unwrap();

src/toolbox/sigma/proof_composition.rs

@@ -61,11 +61,14 @@ where
             commitment: &Self::Commitment,
             challenge: &Self::Challenge,
             response: &Self::Response,
-        ) -> bool {
+        ) -> Result<(), ()> {
         let verif0 = self.protocol0.verifier(&commitment.0, challenge, &response.0);
         let verif1 = self.protocol1.verifier(&commitment.1, challenge, &response.1);
 
-        verif0 & verif1
+        match (verif0, verif1) {
+            (Ok(()), Ok(())) => Ok(()),
+            _ => Err(()),
+        }
     }
 }
 
@@ -174,12 +177,15 @@ where
         commitments: &Self::Commitment,
         challenge: &Self::Challenge,
         response: &Self::Response,
-    ) -> bool {
+    ) -> Result<(), ()> {
         let cond0 = self.protocol0.verifier(&commitments.0, &response.0, &response.1);
 
         let challenge1 = *challenge - response.0;
         let cond1 = self.protocol1.verifier(&commitments.1, &challenge1, &response.2);
 
-        cond0 & cond1
+        match (cond0, cond1) {
+            (Ok(()), Ok(())) => Ok(()),
+            _ => Err(()),
+        }
     }
 }

src/toolbox/sigma/schnorr_proof.rs

@@ -56,13 +56,16 @@ where
         commitment: &Self::Commitment,
         challenge: &Self::Challenge,
         response: &Self::Response,
-    ) -> bool {
+    ) -> Result<(), ()> {
         let lhs = self.morphismp.morphism.evaluate(&response);
         let mut rhs = Vec::new();
         for i in 0..self.morphismp.morphism.num_scalars {
             rhs.push(commitment[i] + self.morphismp.morphism.group_elements[self.morphismp.image[i]] * *challenge);
         }
-        lhs == rhs
+        match lhs == rhs {
+            true => Ok(()),
+            false => Err(()), 
+        }
     }
 
     fn serialize_batchable(

src/toolbox/sigma/trait.rs

@@ -25,7 +25,7 @@ pub trait SigmaProtocol {
         commitment: &Self::Commitment,
         challenge: &Self::Challenge,
         response: &Self::Response,
-    ) -> bool;
+    ) -> Result<(), ()>;
 
     fn simulate_proof(
         &self, 

tests/non_interactive_protocol.rs

@@ -45,7 +45,7 @@ fn fiat_shamir_schnorr_proof_ristretto() {
     let proof_bytes = nizk.prove(&witness, &mut rng);
 
     // Verify
-    let verified = nizk.verify(&proof_bytes);
+    let verified = nizk.verify(&proof_bytes) == Ok(());
 
     assert!(verified, "Fiat-Shamir Schnorr proof verification failed");
 }

tests/proof_composition_test.rs

@@ -1,5 +1,3 @@
-use std::ops::Not;
-
 use rand::{rngs::OsRng, CryptoRng, Rng};
 use sigma_rs::toolbox::sigma::{proof_composition::OrEnum, AndProtocol, OrProtocol, SigmaProtocol};
 use curve25519_dalek::{ristretto::RistrettoPoint, scalar::Scalar};
@@ -41,8 +39,11 @@ impl SigmaProtocol for SchnorrZkp {
             commitment: &Self::Commitment,
             challenge: &Self::Challenge,
             response: &Self::Response,
-        ) -> bool {
-        response * self.generator == challenge * self.target + commitment
+        ) -> Result<(), ()> {
+        match response * self.generator == challenge * self.target + commitment {
+            true => Ok(()),
+            false => Err(()),
+        }
     }
 
     fn simulate_proof(
@@ -97,7 +98,7 @@ fn andproof_schnorr_correct() {
     // Verifier checks
     let result = and_proof.verifier(&commitments, &challenge, &responses);
 
-    assert!(result);
+    assert!(result == Ok(()));
 }
 
 #[allow(non_snake_case)]
@@ -134,7 +135,7 @@ fn andproof_schnorr_incorrect() {
     // Verifier checks
     let result = and_proof.verifier(&commitments, &challenge, &responses);
 
-    assert!(result.not());
+    assert!(result == Err(()));
 }
 
 #[allow(non_snake_case)]
@@ -169,7 +170,7 @@ fn orproof_schnorr_correct() {
     // Verifier checks
     let result = or_proof.verifier(&commitments, &challenge, &responses);
 
-    assert!(result);
+    assert!(result == Ok(()));
 }
 
 #[allow(non_snake_case)]
@@ -204,5 +205,5 @@ fn orproof_schnorr_incorrect() {
     // Verifier checks
     let result = or_proof.verifier(&commitments, &challenge, &responses);
 
-    assert!(result.not());
+    assert!(result == Err(()));
 }