der error handling fixups

Companion PR to RustCrypto/formats#1889

Author: tarcieri

Cargo.lock

@@ -25,3 +25,9 @@ lms-signature = { path = "./lms" }
 ml-dsa = { path = "./ml-dsa" }
 rfc6979 = { path = "./rfc6979" }
 slh-dsa = { path = "./slh-dsa" }
+
+der = { git = "https://github.com/RustCrypto/formats.git" }
+pkcs8 = { git = "https://github.com/RustCrypto/formats.git" }
+sec1 = { git = "https://github.com/RustCrypto/formats.git" }
+
+elliptic-curve = { git = "https://github.com/RustCrypto/traits.git" }

Cargo.toml

@@ -95,7 +95,7 @@ impl<'a> DecodeValue<'a> for Components {
         let q = BoxedUint::from_be_slice_vartime(q.as_bytes());
         let g = BoxedUint::from_be_slice_vartime(g.as_bytes());
 
-        Self::from_components(p, q, g).map_err(|_| Tag::Integer.value_error())
+        Self::from_components(p, q, g).map_err(|_| reader.error(Tag::Integer.value_error()))
     }
 }
 

dsa/src/components.rs

@@ -117,18 +117,16 @@ impl Signature {
 impl<'a> DecodeValue<'a> for Signature {
     type Error = der::Error;
 
-    fn decode_value<R: Reader<'a>>(reader: &mut R, header: Header) -> der::Result<Self> {
-        reader.read_nested(header.length, |reader| {
-            let r = UintRef::decode(reader)?;
-            let s = UintRef::decode(reader)?;
-
-            let r = BoxedUint::from_be_slice(r.as_bytes(), r.as_bytes().len() as u32 * 8)
-                .map_err(|_| UintRef::TAG.value_error())?;
-            let s = BoxedUint::from_be_slice(s.as_bytes(), s.as_bytes().len() as u32 * 8)
-                .map_err(|_| UintRef::TAG.value_error())?;
-
-            Self::from_components(r, s).ok_or_else(|| UintRef::TAG.value_error())
-        })
+    fn decode_value<R: Reader<'a>>(reader: &mut R, _header: Header) -> der::Result<Self> {
+        let r = UintRef::decode(reader)?;
+        let s = UintRef::decode(reader)?;
+
+        let r = BoxedUint::from_be_slice(r.as_bytes(), r.as_bytes().len() as u32 * 8)
+            .map_err(|_| UintRef::TAG.value_error())?;
+        let s = BoxedUint::from_be_slice(s.as_bytes(), s.as_bytes().len() as u32 * 8)
+            .map_err(|_| UintRef::TAG.value_error())?;
+
+        Self::from_components(r, s).ok_or_else(|| reader.error(UintRef::TAG.value_error()))
     }
 }
 

dsa/src/lib.rs

@@ -121,7 +121,7 @@ where
 
         sig.encode_to_slice(&mut bytes)?
             .try_into()
-            .map_err(|_| Tag::Sequence.value_error())
+            .map_err(|_| Tag::Sequence.value_error().into())
     }
 
     /// Borrow this signature as a byte slice
@@ -210,10 +210,10 @@ where
         let len = (header.encoded_len()? + header.length)?;
         let slice = buf
             .get_mut(..usize::try_from(len)?)
-            .ok_or_else(|| reader.error(Tag::Sequence.length_error().kind()))?;
+            .ok_or_else(|| reader.error(Tag::Sequence.length_error()))?;
 
         reader.read_into(slice)?;
-        Self::from_bytes(slice).map_err(|_| Tag::Integer.value_error())
+        Self::from_bytes(slice).map_err(|_| reader.error(Tag::Integer.value_error()))
     }
 }
 

ecdsa/src/der.rs

@@ -734,7 +734,7 @@ where
             &EncodedVerifyingKey::<P>::try_from(
                 spki.subject_public_key
                     .as_bytes()
-                    .ok_or_else(|| der::Tag::BitString.value_error())?,
+                    .ok_or_else(|| der::Tag::BitString.value_error().to_error())?,
             )
             .map_err(|_| pkcs8::Error::KeyMalformed)?,
         ))

ml-dsa/src/lib.rs

@@ -206,7 +206,7 @@ impl<P: ParameterSet> TryFrom<pkcs8::SubjectPublicKeyInfoRef<'_>> for VerifyingK
         Ok(Self::try_from(
             spki.subject_public_key
                 .as_bytes()
-                .ok_or_else(|| der::Tag::BitString.value_error())?,
+                .ok_or_else(|| der::Tag::BitString.value_error().to_error())?,
         )
         .map_err(|_| pkcs8::Error::KeyMalformed)?)
     }