Use a specific error type in verification

Otherwise clippy is complaining

nucypher-core/src/lib.rs

@@ -20,6 +20,9 @@ mod revocation_order;
 mod treasure_map;
 mod versioning;
 
+/// Error returned by various `verify()` methods in the crate.
+pub struct VerificationError;
+
 pub use address::Address;
 pub use fleet_state::FleetStateChecksum;
 pub use hrac::HRAC;

nucypher-core/src/node_metadata.rs

@@ -15,6 +15,7 @@ use crate::fleet_state::FleetStateChecksum;
 use crate::versioning::{
     messagepack_deserialize, messagepack_serialize, ProtocolObject, ProtocolObjectInner,
 };
+use crate::VerificationError;
 
 impl SerializeAsBytes for recoverable::Signature {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
@@ -275,14 +276,17 @@ impl MetadataResponse {
     }
 
     /// Verifies the metadata response and returns the contained payload.
-    pub fn verify(self, verifying_pk: &PublicKey) -> Result<MetadataResponsePayload, ()> {
+    pub fn verify(
+        self,
+        verifying_pk: &PublicKey,
+    ) -> Result<MetadataResponsePayload, VerificationError> {
         if self
             .signature
             .verify(verifying_pk, &self.payload.to_bytes())
         {
             Ok(self.payload)
         } else {
-            Err(())
+            Err(VerificationError)
         }
     }
 }

nucypher-core/src/reencryption.rs

@@ -12,6 +12,7 @@ use crate::key_frag::EncryptedKeyFrag;
 use crate::versioning::{
     messagepack_deserialize, messagepack_serialize, ProtocolObject, ProtocolObjectInner,
 };
+use crate::VerificationError;
 
 /// A request for an Ursula to reencrypt for several capsules.
 #[derive(PartialEq, Debug, Serialize, Deserialize)]
@@ -121,18 +122,18 @@ impl ReencryptionResponse {
         ursula_verifying_key: &PublicKey,
         policy_encrypting_key: &PublicKey,
         bob_encrypting_key: &PublicKey,
-    ) -> Result<Box<[VerifiedCapsuleFrag]>, ()> {
+    ) -> Result<Box<[VerifiedCapsuleFrag]>, VerificationError> {
         if capsules.len() != self.cfrags.len() {
             // Mismatched number of capsules and cfrags
-            return Err(());
+            return Err(VerificationError);
         }
 
         // Validate re-encryption signature
         if !self.signature.verify(
             ursula_verifying_key,
             &signed_message(capsules, &self.cfrags),
         ) {
-            return Err(());
+            return Err(VerificationError);
         }
 
         let vcfrags = self
@@ -154,7 +155,7 @@ impl ReencryptionResponse {
         // in the error case, but at this point nobody's interested in that.
         vcfrags
             .map(|vcfrags| vcfrags.into_boxed_slice())
-            .map_err(|_err| ())
+            .map_err(|_err| VerificationError)
     }
 }
 

nucypher-core/src/revocation_order.rs

@@ -9,6 +9,7 @@ use crate::key_frag::EncryptedKeyFrag;
 use crate::versioning::{
     messagepack_deserialize, messagepack_serialize, ProtocolObject, ProtocolObjectInner,
 };
+use crate::VerificationError;
 
 /// Represents a string used by characters to perform a revocation on a specific Ursula.
 #[derive(PartialEq, Debug, Clone, Serialize, Deserialize)]
@@ -43,7 +44,7 @@ impl RevocationOrder {
     pub fn verify(
         self,
         alice_verifying_key: &PublicKey,
-    ) -> Result<(Address, EncryptedKeyFrag), ()> {
+    ) -> Result<(Address, EncryptedKeyFrag), VerificationError> {
         let message = [
             self.staking_provider_address.as_ref(),
             &self.encrypted_kfrag.to_bytes(),
@@ -52,7 +53,7 @@ impl RevocationOrder {
         if self.signature.verify(alice_verifying_key, &message) {
             Ok((self.staking_provider_address, self.encrypted_kfrag))
         } else {
-            Err(())
+            Err(VerificationError)
         }
     }
 }