add public key algorithm

rcgen/src/crl.rs

@@ -28,11 +28,12 @@ use crate::{
 /// #[cfg(not(feature = "crypto"))]
 /// impl SigningKey for MyKeyPair {
 ///   fn sign(&self, _: &[u8]) -> Result<Vec<u8>, rcgen::Error> { Ok(vec![]) }
+///   fn algorithm(&self) -> &'static SignatureAlgorithm { &ED25519 }
 /// }
 /// #[cfg(not(feature = "crypto"))]
 /// impl PublicKeyData for MyKeyPair {
 ///   fn der_bytes(&self) -> &[u8] { &self.public_key }
-///   fn algorithm(&self) -> &'static SignatureAlgorithm { &ED25519 }
+///   fn key_algorithm(&self) -> &'static PublicKeyAlgorithm { &key_alg::ED25519 }
 /// }
 /// # fn main () {
 /// // Generate a CRL issuer.

rcgen/src/csr.rs

@@ -7,7 +7,7 @@ use pki_types::CertificateSigningRequestDer;
 #[cfg(feature = "pem")]
 use crate::ENCODE_CONFIG;
 use crate::{
-	Certificate, CertificateParams, Error, Issuer, PublicKeyData, SignatureAlgorithm, SigningKey,
+	Certificate, CertificateParams, Error, Issuer, PublicKeyAlgorithm, PublicKeyData, SigningKey,
 };
 #[cfg(feature = "x509-parser")]
 use crate::{DistinguishedName, ExtendedKeyUsagePurpose, GeneralName, IsCa, KeyUsagePurpose};
@@ -16,12 +16,12 @@ use crate::{DistinguishedName, ExtendedKeyUsagePurpose, GeneralName, IsCa, KeyUs
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct PublicKey {
 	raw: Vec<u8>,
-	alg: &'static SignatureAlgorithm,
+	alg: &'static PublicKeyAlgorithm,
 }
 
 impl PublicKey {
-	/// The algorithm used to generate the public key and sign the CSR.
-	pub fn algorithm(&self) -> &SignatureAlgorithm {
+	/// The algorithm of the public key
+	pub fn algorithm(&self) -> &'static PublicKeyAlgorithm {
 		self.alg
 	}
 }
@@ -31,7 +31,7 @@ impl PublicKeyData for PublicKey {
 		&self.raw
 	}
 
-	fn algorithm(&self) -> &'static SignatureAlgorithm {
+	fn key_algorithm(&self) -> &'static PublicKeyAlgorithm {
 		self.alg
 	}
 }
@@ -116,20 +116,18 @@ impl CertificateSigningRequestParams {
 			.1;
 		csr.verify_signature()
 			.map_err(|_| Error::InvalidCertificationRequestSignature)?;
-		let alg_oid = csr
-			.signature_algorithm
-			.algorithm
-			.iter()
-			.ok_or(Error::CouldNotParseCertificationRequest)?
-			.collect::<Vec<_>>();
-		let alg = SignatureAlgorithm::from_oid(&alg_oid)?;
 
 		let info = &csr.certification_request_info;
+
+		let public_key = PublicKey {
+			raw: info.subject_pki.subject_public_key.data.to_vec(),
+			alg: PublicKeyAlgorithm::from_alg_id(&info.subject_pki.algorithm)?,
+		};
+
 		let mut params = CertificateParams {
 			distinguished_name: DistinguishedName::from_name(&info.subject)?,
 			..CertificateParams::default()
 		};
-		let raw = info.subject_pki.subject_public_key.data.to_vec();
 
 		if let Some(extensions) = csr.requested_extensions() {
 			for ext in extensions {
@@ -186,10 +184,7 @@ impl CertificateSigningRequestParams {
 		// * name_constraints
 		// and any other extensions.
 
-		Ok(Self {
-			params,
-			public_key: PublicKey { alg, raw },
-		})
+		Ok(Self { params, public_key })
 	}
 
 	/// Generate a new certificate based on the requested parameters, signed by the provided

rcgen/src/error.rs

@@ -28,6 +28,8 @@ pub enum Error {
 	UnsupportedExtension,
 	/// The requested signature algorithm is not supported
 	UnsupportedSignatureAlgorithm,
+	/// The public key algorithm is not supported
+	UnsupportedPublicKeyAlgorithm,
 	/// Unspecified `ring` error
 	RingUnspecified,
 	/// The `ring` library rejected the key upon loading
@@ -84,6 +86,11 @@ impl fmt::Display for Error {
 				"The requested signature algorithm \
 				is not supported"
 			)?,
+			UnsupportedPublicKeyAlgorithm => write!(
+				f,
+				"The public key algorithm \
+				is not supported"
+			)?,
 			#[cfg(feature = "x509-parser")]
 			UnsupportedExtension => write!(f, "Unsupported extension requested in CSR")?,
 			RingUnspecified => write!(f, "Unspecified ring error")?,

rcgen/src/key_pair.rs

@@ -26,9 +26,9 @@ use crate::ring_like::{
 	},
 	{ecdsa_from_pkcs8, rsa_key_pair_public_modulus_len},
 };
-use crate::sign_algo::SignatureAlgorithm;
 #[cfg(feature = "crypto")]
 use crate::sign_algo::{algo::*, SignAlgo};
+use crate::sign_algo::{PublicKeyAlgorithm, SignatureAlgorithm};
 use crate::Error;
 #[cfg(feature = "pem")]
 use crate::ENCODE_CONFIG;
@@ -181,11 +181,6 @@ impl KeyPair {
 		))
 	}
 
-	/// Returns the key pair's signature algorithm
-	pub fn algorithm(&self) -> &'static SignatureAlgorithm {
-		self.alg
-	}
-
 	/// Parses the key pair from the ASCII PEM format
 	///
 	/// If `aws_lc_rs` feature is used, then the key must be a DER-encoded plaintext private key; as specified in PKCS #8/RFC 5958, SEC1/RFC 5915, or PKCS#1/RFC 3447;
@@ -448,6 +443,10 @@ impl SigningKey for KeyPair {
 			},
 		})
 	}
+
+	fn algorithm(&self) -> &'static SignatureAlgorithm {
+		self.alg
+	}
 }
 
 #[cfg(feature = "crypto")]
@@ -462,8 +461,8 @@ impl PublicKeyData for KeyPair {
 		}
 	}
 
-	fn algorithm(&self) -> &'static SignatureAlgorithm {
-		self.alg
+	fn key_algorithm(&self) -> &'static PublicKeyAlgorithm {
+		self.alg.public_key_algorithm()
 	}
 }
 
@@ -611,12 +610,19 @@ impl<S: SigningKey + ?Sized> SigningKey for &S {
 	fn sign(&self, msg: &[u8]) -> Result<Vec<u8>, Error> {
 		(*self).sign(msg)
 	}
+
+	fn algorithm(&self) -> &'static SignatureAlgorithm {
+		(*self).algorithm()
+	}
 }
 
 /// A key that can be used to sign messages
 pub trait SigningKey: PublicKeyData {
 	/// Signs `msg` using the selected algorithm
 	fn sign(&self, msg: &[u8]) -> Result<Vec<u8>, Error>;
+
+	/// The algorithm of the signatures this key produces
+	fn algorithm(&self) -> &'static SignatureAlgorithm;
 }
 
 #[cfg(feature = "crypto")]
@@ -643,7 +649,7 @@ impl<T> ExternalError<T> for Result<T, pem::PemError> {
 /// A public key
 #[derive(Clone, Debug, Eq, PartialEq)]
 pub struct SubjectPublicKeyInfo {
-	pub(crate) alg: &'static SignatureAlgorithm,
+	pub(crate) alg: &'static PublicKeyAlgorithm,
 	pub(crate) subject_public_key: Vec<u8>,
 }
 
@@ -658,7 +664,7 @@ impl SubjectPublicKeyInfo {
 	#[cfg(feature = "x509-parser")]
 	pub fn from_der(spki_der: &[u8]) -> Result<Self, Error> {
 		use x509_parser::prelude::FromDer;
-		use x509_parser::x509::{AlgorithmIdentifier, SubjectPublicKeyInfo};
+		use x509_parser::x509::SubjectPublicKeyInfo;
 
 		let (rem, spki) =
 			SubjectPublicKeyInfo::from_der(spki_der).map_err(|e| Error::X509(e.to_string()))?;
@@ -668,23 +674,8 @@ impl SubjectPublicKeyInfo {
 			));
 		}
 
-		let alg = SignatureAlgorithm::iter()
-			.find(|alg| {
-				let bytes = yasna::construct_der(|writer| {
-					alg.write_oids_sign_alg(writer);
-				});
-				let Ok((rest, aid)) = AlgorithmIdentifier::from_der(&bytes) else {
-					return false;
-				};
-				if !rest.is_empty() {
-					return false;
-				}
-				aid == spki.algorithm
-			})
-			.ok_or(Error::UnsupportedSignatureAlgorithm)?;
-
 		Ok(Self {
-			alg,
+			alg: PublicKeyAlgorithm::from_alg_id(&spki.algorithm)?,
 			subject_public_key: Vec::from(spki.subject_public_key.as_ref()),
 		})
 	}
@@ -695,7 +686,7 @@ impl PublicKeyData for SubjectPublicKeyInfo {
 		&self.subject_public_key
 	}
 
-	fn algorithm(&self) -> &'static SignatureAlgorithm {
+	fn key_algorithm(&self) -> &'static PublicKeyAlgorithm {
 		self.alg
 	}
 }
@@ -705,8 +696,8 @@ impl<K: PublicKeyData + ?Sized> PublicKeyData for &K {
 		(*self).der_bytes()
 	}
 
-	fn algorithm(&self) -> &'static SignatureAlgorithm {
-		(*self).algorithm()
+	fn key_algorithm(&self) -> &'static PublicKeyAlgorithm {
+		(*self).key_algorithm()
 	}
 }
 
@@ -723,8 +714,8 @@ pub trait PublicKeyData {
 	/// The public key in DER format
 	fn der_bytes(&self) -> &[u8];
 
-	/// The algorithm used by the key pair
-	fn algorithm(&self) -> &'static SignatureAlgorithm;
+	/// The algorithm of the public key
+	fn key_algorithm(&self) -> &'static PublicKeyAlgorithm;
 }
 
 /// Serialize private key to PEM format
@@ -743,7 +734,7 @@ pub fn serialize_private_key_pem(key: &PrivateKeyDer<'_>) -> Result<String, Erro
 
 pub(crate) fn serialize_public_key_der(key: &(impl PublicKeyData + ?Sized), writer: DERWriter) {
 	writer.write_sequence(|writer| {
-		key.algorithm().write_oids_sign_alg(writer.next());
+		key.key_algorithm().write_alg_id(writer.next());
 		let pk = key.der_bytes();
 		writer.next().write_bitvec_bytes(pk, pk.len() * 8);
 	})
@@ -776,6 +767,11 @@ mod test {
 
 			let pkd_der = SubjectPublicKeyInfo::from_der(&der).expect("from der");
 			assert_eq!(kp.der_bytes(), pkd_der.der_bytes());
+
+			// Several signature algorithms can share an SPKI encoding, so this recovery is
+			// only unambiguous because it resolves to a key algorithm.
+			assert_eq!(pkd_der.key_algorithm(), alg.public_key_algorithm());
+			assert_eq!(pkd_der.subject_public_key_info(), der);
 		}
 	}
 
@@ -787,5 +783,6 @@ mod test {
 
 		let key_pair = KeyPair::try_from(der).unwrap();
 		assert_eq!(key_pair.algorithm(), &ECDSA_P256_SHA256);
+		assert_eq!(key_pair.key_algorithm(), &crate::key_alg::ECDSA_P256);
 	}
 }

rcgen/src/lib.rs

@@ -83,7 +83,7 @@ pub use key_pair::{PublicKeyData, SigningKey, SubjectPublicKeyInfo};
 
 mod sign_algo;
 pub use sign_algo::algo::*;
-pub use sign_algo::SignatureAlgorithm;
+pub use sign_algo::{key_alg, PublicKeyAlgorithm, SignatureAlgorithm};
 
 mod oid;
 
@@ -679,4 +679,27 @@ mod tests {
 			}
 		}
 	}
+
+	#[test]
+	fn algo_hash_agrees_with_eq() {
+		use std::collections::hash_map::DefaultHasher;
+		use std::hash::{Hash, Hasher};
+
+		fn hash(value: &impl Hash) -> u64 {
+			let mut hasher = DefaultHasher::new();
+			value.hash(&mut hasher);
+			hasher.finish()
+		}
+
+		for alg_i in SignatureAlgorithm::iter() {
+			for alg_j in SignatureAlgorithm::iter() {
+				assert!(alg_i != alg_j || hash(alg_i) == hash(alg_j));
+			}
+		}
+		for alg_i in PublicKeyAlgorithm::iter() {
+			for alg_j in PublicKeyAlgorithm::iter() {
+				assert!(alg_i != alg_j || hash(alg_i) == hash(alg_j));
+			}
+		}
+	}
 }