verify: fix verify function return type to be bool

commit_verify/src/commit.rs

@@ -43,6 +43,7 @@ where Self: Eq + Sized
     /// Verifies commitment against the message; default implementation just
     /// repeats the commitment to the message and check it against the `self`.
     #[inline]
+    #[must_use = "the boolean carries the result of the verification"]
     fn verify(&self, msg: &Msg) -> bool { Self::commit(msg) == *self }
 }
 
@@ -59,12 +60,15 @@ where Self: Eq + Sized
     /// Tries to create commitment to a byte representation of a given message
     fn try_commit(msg: &Msg) -> Result<Self, Self::Error>;
 
-    /// Tries to verify commitment against the message; default implementation
+    /// Verifies commitment against the message; default implementation
     /// just repeats the commitment to the message and check it against the
     /// `self`.
     #[inline]
-    fn try_verify(&self, msg: &Msg) -> Result<bool, Self::Error> {
-        Ok(Self::try_commit(msg)? == *self)
+    #[must_use = "the boolean carries the result of the verification"]
+    fn verify(&self, msg: &Msg) -> bool {
+        Self::try_commit(msg)
+            .map(|other| other == *self)
+            .unwrap_or(false)
     }
 }
 

commit_verify/src/convolve.rs

@@ -49,34 +49,19 @@ where
     /// that the resulting commitment matches the provided one in the
     /// `commitment` parameter.
     ///
-    /// Errors if the commitment can't be created, i.e. the
-    /// [`ConvolveCommit::convolve_commit`] procedure for the original,
-    /// restored from the proof, can't be performed. This means that the
-    /// verification has failed and the commitment and/or the proof are
-    /// invalid. The function returns error in this case (ano not simply
-    /// `false`) since this usually means the software error in managing
-    /// container and proof data, or selection of a different commitment
-    /// protocol parameters comparing to the ones used during commitment
-    /// creation. In all these cases we'd like to provide devs with more
-    /// information for debugging.
-    ///
-    /// The proper way of using the function in a well-debugged software should
-    /// be `if commitment.verify(...).expect("proof managing system") { .. }`.
-    /// However if the proofs are provided by some sort of user/network input
-    /// from an untrusted party, a proper form would be
-    /// `if commitment.verify(...).unwrap_or(false) { .. }`.
-    fn verify(
-        &self,
-        msg: &Msg,
-        commitment: &Source::Commitment,
-    ) -> Result<bool, Source::CommitError>
-    where
-        Self: VerifyEq,
-    {
+    /// Returns `false` if the commitment doesn't pass the verification or can't
+    /// be replicated, i.e. the [`ConvolveCommit::convolve_commit`]
+    /// procedure for the original, restored from the proof, can't be
+    /// performed. This means that the verification has failed and the
+    /// commitment and/or the proof are invalid.
+    #[must_use = "the boolean carries the result of the verification"]
+    fn verify(&self, msg: &Msg, commitment: &Source::Commitment) -> bool {
         let original = self.restore_original(commitment);
         let suppl = self.extract_supplement();
-        let (commitment_prime, proof) = original.convolve_commit(suppl, msg)?;
-        Ok(commitment.verify_eq(&commitment_prime) && self.verify_eq(&proof))
+        let Ok((commitment_prime, proof)) = original.convolve_commit(suppl, msg) else {
+            return false;
+        };
+        commitment.verify_eq(&commitment_prime) && self.verify_eq(&proof)
     }
 }
 

commit_verify/src/embed.rs

@@ -47,10 +47,9 @@ where
 {
     /// Restores original container before the commitment from the proof data
     /// and a container containing embedded commitment.
-    fn restore_original_container(
-        &self,
-        commit_container: &Container,
-    ) -> Result<Container, Container::VerifyError>;
+    ///
+    /// Can fail if the container data are not match proof data.
+    fn restore_original_container(&self, commit_container: &Container) -> Option<Container>;
 }
 
 /// Trait for *embed-commit-verify scheme*, where some data structure (named
@@ -113,10 +112,6 @@ where
     /// invalid and the commitment can't be re-created.
     type CommitError: std::error::Error;
 
-    /// Error type that may be reported during [`Self::verify`] procedure.
-    /// It must be a subset of [`Self::CommitError`].
-    type VerifyError: std::error::Error + From<Self::CommitError>;
-
     /// Creates a commitment to a message and embeds it into the provided
     /// container (`self`) by mutating it and returning commitment proof.
     ///
@@ -131,31 +126,26 @@ where
     /// [`Self::embed_commit`] procedure checking that the resulting proof and
     /// commitment matches the provided `self` and `proof`.
     ///
-    /// Errors if the provided commitment can't be created, i.e. the
-    /// [`Self::embed_commit`] procedure for the original container, restored
-    /// from the proof and current container, can't be performed. This means
-    /// that the verification has failed and the commitment and proof are
-    /// invalid. The function returns error in this case (ano not simply
-    /// `false`) since this usually means the software error in managing
-    /// container and proof data, or selection of a different commitment
-    /// protocol parameters comparing to the ones used during commitment
-    /// creation. In all these cases we'd like to provide devs with more
-    /// information for debugging.
-    ///
-    /// The proper way of using the function in a well-debugged software should
-    /// be `if commitment.verify(...).expect("proof managing system") { .. }`.
-    /// However if the proofs are provided by some sort of user/network input
-    /// from an untrusted party, a proper form would be
-    /// `if commitment.verify(...).unwrap_or(false) { .. }`.
+    /// Returns `false` if the if the commitment doesn't pass the verification
+    /// or can't be replicated, i.e. the original container can't be restored
+    /// from the proof, or [`Self::embed_commit`] procedure for the original
+    /// container, restored from the proof and current container, can't be
+    /// performed. All of these options mean that the verification has failed
+    /// and the commitment or the proof is invalid.
     #[inline]
-    fn verify(&self, msg: &Msg, proof: &Self::Proof) -> Result<bool, Self::VerifyError>
+    #[must_use = "the boolean carries the result of the verification"]
+    fn verify(&self, msg: &Msg, proof: &Self::Proof) -> bool
     where
         Self: VerifyEq,
         Self::Proof: VerifyEq,
     {
-        let mut container_prime = proof.restore_original_container(self)?;
-        let proof_prime = container_prime.embed_commit(msg)?;
-        Ok(proof_prime.verify_eq(proof) && self.verify_eq(&container_prime))
+        let Some(mut container_prime) = proof.restore_original_container(self) else {
+            return false;
+        };
+        let Ok(proof_prime) = container_prime.embed_commit(msg) else {
+            return false;
+        };
+        proof_prime.verify_eq(proof) && self.verify_eq(&container_prime)
     }
 
     /// Phantom method used to add `Protocol` generic parameter to the trait.