Remove panics from batch verification API in lieu of better error handling.

src/ed25519.rs

@@ -50,11 +50,6 @@ pub use crate::signature::*;
 /// * `public_keys` is a slice of `PublicKey`s.
 /// * `csprng` is an implementation of `Rng + CryptoRng`.
 ///
-/// # Panics
-///
-/// This function will panic if the `messages, `signatures`, and `public_keys`
-/// slices are not equal length.
-///
 /// # Returns
 ///
 /// * A `Result` whose `Ok` value is an emtpy tuple and whose `Err` value is a
@@ -93,10 +88,15 @@ pub fn verify_batch(
     public_keys: &[PublicKey],
 ) -> Result<(), SignatureError>
 {
-    const ASSERT_MESSAGE: &'static str = "The number of messages, signatures, and public keys must be equal.";
+    if signatures.len() != messages.len() ||
-    assert!(signatures.len()  == messages.len(),    ASSERT_MESSAGE);
+        signatures.len() != public_keys.len() ||
-    assert!(signatures.len()  == public_keys.len(), ASSERT_MESSAGE);
+        public_keys.len() != messages.len() {
-    assert!(public_keys.len() == messages.len(),    ASSERT_MESSAGE);
+        return Err(SignatureError(InternalError::ArrayLengthError{
+            name_a: "signatures", length_a: signatures.len(),
+            name_b: "messages", length_b: messages.len(),
+            name_c: "public_keys", length_c: public_keys.len(),
+        }));
+    }
 
     #[cfg(feature = "alloc")]
     use alloc::vec::Vec;

src/errors.rs

@@ -33,6 +33,11 @@ pub(crate) enum InternalError {
     },
     /// The verification equation wasn't satisfied
     VerifyError,
+    /// Two arrays did not match in size, making the called signature
+    /// verification method impossible.
+    ArrayLengthError{ name_a: &'static str, length_a: usize,
+                      name_b: &'static str, length_b: usize,
+                      name_c: &'static str, length_c: usize, },
 }
 
 impl Display for InternalError {
@@ -46,6 +51,11 @@ impl Display for InternalError {
                 => write!(f, "{} must be {} bytes in length", n, l),
             InternalError::VerifyError
                 => write!(f, "Verification equation was not satisfied"),
+            InternalError::ArrayLengthError{ name_a: na, length_a: la,
+                                             name_b: nb, length_b: lb,
+                                             name_c: nc, length_c: lc, }
+                => write!(f, "Arrays must be the same length: {} has length {},
+                              {} has length {}, {} has length {}.", na, la, nb, lb, nc, lc),
         }
     }
 }