der: remove inherent AnyRef decoding methods

der/src/asn1/any.rs

@@ -1,18 +1,16 @@
 //! ASN.1 `ANY` type.
+
 #![cfg_attr(feature = "arbitrary", allow(clippy::integer_arithmetic))]
 
 use crate::{
-    asn1::*, BytesRef, Choice, Decode, DecodeValue, DerOrd, EncodeValue, Error, ErrorKind,
-    FixedTag, Header, Length, Reader, Result, SliceReader, Tag, Tagged, ValueOrd, Writer,
+    BytesRef, Choice, Decode, DecodeValue, DerOrd, EncodeValue, Error, ErrorKind, Header, Length,
+    Reader, Result, SliceReader, Tag, Tagged, ValueOrd, Writer,
 };
 use core::cmp::Ordering;
 
 #[cfg(feature = "alloc")]
 use {crate::BytesOwned, alloc::boxed::Box};
 
-#[cfg(feature = "oid")]
-use crate::asn1::ObjectIdentifier;
-
 /// ASN.1 `ANY`: represents any explicitly tagged ASN.1 value.
 ///
 /// This is a zero-copy reference type which borrows from the input data.
@@ -58,11 +56,14 @@ impl<'a> AnyRef<'a> {
     }
 
     /// Attempt to decode this [`AnyRef`] type into the inner value.
-    pub fn decode_into<T>(self) -> Result<T>
+    pub fn decode_as<T>(self) -> Result<T>
     where
-        T: DecodeValue<'a> + FixedTag,
+        T: Choice<'a> + DecodeValue<'a>,
     {
-        self.tag.assert_eq(T::TAG)?;
+        if !T::can_decode(self.tag) {
+            return Err(self.tag.unexpected_error(None));
+        }
+
         let header = Header {
             tag: self.tag,
             length: self.value.len(),
@@ -78,48 +79,6 @@ impl<'a> AnyRef<'a> {
         self == Self::NULL
     }
 
-    /// Attempt to decode an ASN.1 `BIT STRING`.
-    pub fn bit_string(self) -> Result<BitStringRef<'a>> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `CONTEXT-SPECIFIC` field.
-    pub fn context_specific<T>(self) -> Result<ContextSpecific<T>>
-    where
-        T: Decode<'a>,
-    {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `GeneralizedTime`.
-    pub fn generalized_time(self) -> Result<GeneralizedTime> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `OCTET STRING`.
-    pub fn octet_string(self) -> Result<OctetStringRef<'a>> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `OBJECT IDENTIFIER`.
-    #[cfg(feature = "oid")]
-    #[cfg_attr(docsrs, doc(cfg(feature = "oid")))]
-    pub fn oid(self) -> Result<ObjectIdentifier> {
-        self.try_into()
-    }
-
-    /// Attempt to decode an ASN.1 `OPTIONAL` value.
-    pub fn optional<T>(self) -> Result<Option<T>>
-    where
-        T: Choice<'a> + TryFrom<Self, Error = Error>,
-    {
-        if T::can_decode(self.tag) {
-            T::try_from(self).map(Some)
-        } else {
-            Ok(None)
-        }
-    }
-
     /// Attempt to decode this value an ASN.1 `SEQUENCE`, creating a new
     /// nested reader and calling the provided argument with it.
     pub fn sequence<F, T>(self, f: F) -> Result<T>
@@ -131,11 +90,6 @@ impl<'a> AnyRef<'a> {
         let result = f(&mut reader)?;
         reader.finish(result)
     }
-
-    /// Attempt to decode an ASN.1 `UTCTime`.
-    pub fn utc_time(self) -> Result<UtcTime> {
-        self.try_into()
-    }
 }
 
 impl<'a> Choice<'a> for AnyRef<'a> {
@@ -231,19 +185,20 @@ impl Any {
     }
 
     /// Attempt to decode this [`Any`] type into the inner value.
-    pub fn decode_into<'a, T>(&'a self) -> Result<T>
+    pub fn decode_as<'a, T>(&'a self) -> Result<T>
     where
-        T: DecodeValue<'a> + FixedTag,
+        T: Choice<'a> + DecodeValue<'a>,
     {
-        self.tag.assert_eq(T::TAG)?;
-        let header = Header {
-            tag: self.tag,
-            length: self.value.len(),
-        };
+        AnyRef::from(self).decode_as()
+    }
 
-        let mut decoder = SliceReader::new(self.value.as_slice())?;
-        let result = T::decode_value(&mut decoder, header)?;
-        decoder.finish(result)
+    /// Attempt to decode this value an ASN.1 `SEQUENCE`, creating a new
+    /// nested reader and calling the provided argument with it.
+    pub fn sequence<'a, F, T>(&'a self, f: F) -> Result<T>
+    where
+        F: FnOnce(&mut SliceReader<'a>) -> Result<T>,
+    {
+        AnyRef::from(self).sequence(f)
     }
 }
 

der/src/asn1/bit_string.rs

@@ -163,7 +163,7 @@ impl<'a> TryFrom<AnyRef<'a>> for BitStringRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<BitStringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 

der/src/asn1/generalized_time.rs

@@ -168,7 +168,7 @@ impl TryFrom<AnyRef<'_>> for GeneralizedTime {
     type Error = Error;
 
     fn try_from(any: AnyRef<'_>) -> Result<GeneralizedTime> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 

der/src/asn1/integer.rs

@@ -65,7 +65,7 @@ macro_rules! impl_int_encoding {
                 type Error = Error;
 
                 fn try_from(any: AnyRef<'_>) -> Result<Self> {
-                    any.decode_into()
+                    any.decode_as()
                 }
             }
         )+
@@ -113,7 +113,7 @@ macro_rules! impl_uint_encoding {
                 type Error = Error;
 
                 fn try_from(any: AnyRef<'_>) -> Result<Self> {
-                    any.decode_into()
+                    any.decode_as()
                 }
             }
         )+

der/src/asn1/integer/bigint.rs

@@ -79,7 +79,7 @@ impl<'a> TryFrom<AnyRef<'a>> for IntRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<IntRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 
@@ -167,7 +167,7 @@ impl<'a> TryFrom<AnyRef<'a>> for UintRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<UintRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 
@@ -265,7 +265,7 @@ mod allocating {
         type Error = Error;
 
         fn try_from(any: AnyRef<'a>) -> Result<Int> {
-            any.decode_into()
+            any.decode_as()
         }
     }
 
@@ -372,7 +372,7 @@ mod allocating {
         type Error = Error;
 
         fn try_from(any: AnyRef<'a>) -> Result<Uint> {
-            any.decode_into()
+            any.decode_as()
         }
     }
 

der/src/asn1/internal_macros.rs

@@ -53,7 +53,7 @@ macro_rules! impl_string_type {
                 type Error = Error;
 
                 fn try_from(any: &'__der Any) -> Result<$type> {
-                    any.decode_into()
+                    any.decode_as()
                 }
             }
         }

der/src/asn1/null.rs

@@ -45,7 +45,7 @@ impl TryFrom<AnyRef<'_>> for Null {
     type Error = Error;
 
     fn try_from(any: AnyRef<'_>) -> Result<Null> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 

der/src/asn1/octet_string.rs

@@ -87,7 +87,7 @@ impl<'a> TryFrom<AnyRef<'a>> for OctetStringRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<OctetStringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 

der/src/asn1/printable_string.rs

@@ -112,7 +112,7 @@ impl<'a> TryFrom<AnyRef<'a>> for PrintableStringRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<PrintableStringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 
@@ -206,7 +206,7 @@ mod allocation {
         type Error = Error;
 
         fn try_from(any: &AnyRef<'a>) -> Result<PrintableString> {
-            (*any).decode_into()
+            (*any).decode_as()
         }
     }
 

der/src/asn1/teletex_string.rs

@@ -83,7 +83,7 @@ impl<'a> TryFrom<AnyRef<'a>> for TeletexStringRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<TeletexStringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 impl<'a> From<TeletexStringRef<'a>> for AnyRef<'a> {
@@ -164,7 +164,7 @@ mod allocation {
         type Error = Error;
 
         fn try_from(any: &AnyRef<'a>) -> Result<TeletexString> {
-            (*any).decode_into()
+            (*any).decode_as()
         }
     }
 

der/src/asn1/utc_time.rs

@@ -191,7 +191,7 @@ impl TryFrom<AnyRef<'_>> for UtcTime {
     type Error = Error;
 
     fn try_from(any: AnyRef<'_>) -> Result<UtcTime> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 

der/src/asn1/utf8_string.rs

@@ -94,7 +94,7 @@ impl<'a> TryFrom<AnyRef<'a>> for Utf8StringRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<Utf8StringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 
@@ -103,7 +103,7 @@ impl<'a> TryFrom<&'a Any> for Utf8StringRef<'a> {
     type Error = Error;
 
     fn try_from(any: &'a Any) -> Result<Utf8StringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 

der/src/asn1/videotex_string.rs

@@ -101,7 +101,7 @@ impl<'a> TryFrom<AnyRef<'a>> for VideotexStringRef<'a> {
     type Error = Error;
 
     fn try_from(any: AnyRef<'a>) -> Result<VideotexStringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 
@@ -110,7 +110,7 @@ impl<'a> TryFrom<&'a Any> for VideotexStringRef<'a> {
     type Error = Error;
 
     fn try_from(any: &'a Any) -> Result<VideotexStringRef<'a>> {
-        any.decode_into()
+        any.decode_as()
     }
 }
 

pkcs1/tests/params.rs

@@ -105,7 +105,11 @@ fn decode_oaep_param() {
         .assert_algorithm_oid(db::rfc5912::ID_P_SPECIFIED)
         .is_ok());
     assert_eq!(
-        param.p_source.parameters_any().unwrap().octet_string(),
+        param
+            .p_source
+            .parameters_any()
+            .unwrap()
+            .decode_as::<OctetStringRef<'_>>(),
         OctetStringRef::new(&[0xab, 0xcd, 0xef])
     );
 }
@@ -147,7 +151,7 @@ fn decode_oaep_param_default() {
         .p_source
         .parameters_any()
         .unwrap()
-        .octet_string()
+        .decode_as::<OctetStringRef<'_>>()
         .unwrap()
         .is_empty(),);
     assert_eq!(param, Default::default())

pkcs5/src/pbes2.rs

@@ -320,7 +320,7 @@ impl<'a> TryFrom<AlgorithmIdentifierRef<'a>> for EncryptionScheme<'a> {
     fn try_from(alg: AlgorithmIdentifierRef<'a>) -> der::Result<Self> {
         // TODO(tarcieri): support for non-AES algorithms?
         let iv = match alg.parameters {
-            Some(params) => params.octet_string()?.as_bytes(),
+            Some(params) => params.decode_as::<OctetStringRef<'a>>()?.as_bytes(),
             None => return Err(Tag::OctetString.value_error()),
         };
 

pkcs7/tests/content_tests.rs

@@ -104,7 +104,7 @@ fn decode_signed_mdm_example() {
             signer_infos: _,
         })) => {
             let _content = content
-                .decode_into::<SequenceRef>()
+                .decode_as::<SequenceRef>()
                 .expect("Content should be in the correct format: SequenceRef");
         }
         _ => panic!("expected ContentInfo::SignedData(Some(_))"),
@@ -132,7 +132,7 @@ fn decode_signed_scep_example() {
             signer_infos: _,
         })) => {
             let _content = content
-                .decode_into::<OctetStringRef>()
+                .decode_as::<OctetStringRef>()
                 .expect("Content should be in the correct format: OctetStringRef");
 
             assert_eq!(ver, CmsVersion::V1)

pkcs8/tests/private_key.rs

@@ -1,5 +1,6 @@
 //! PKCS#8 private key tests
 
+use der::asn1::ObjectIdentifier;
 use hex_literal::hex;
 use pkcs8::{PrivateKeyInfo, Version};
 
@@ -48,7 +49,11 @@ fn decode_ec_p256_der() {
     assert_eq!(pk.algorithm.oid, "1.2.840.10045.2.1".parse().unwrap());
 
     assert_eq!(
-        pk.algorithm.parameters.unwrap().oid().unwrap(),
+        pk.algorithm
+            .parameters
+            .unwrap()
+            .decode_as::<ObjectIdentifier>()
+            .unwrap(),
         "1.2.840.10045.3.1.7".parse().unwrap()
     );
 

spki/src/algorithm.rs

@@ -157,7 +157,7 @@ impl<'a> AlgorithmIdentifierRef<'a> {
                 None => None,
                 Some(p) => match p {
                     AnyRef::NULL => None,
-                    _ => Some(p.oid()?),
+                    _ => Some(p.decode_as::<ObjectIdentifier>()?),
                 },
             },
         ))