key_pair: emphasize PKCS8 in from der & alg constructor

The `KeyPair::from_der_and_sign_algo` fn expects PKCS8 formatted DER as
input. This commit renames the fn to
`Keypair::from_pkcs8_der_and_sign_algo` to emphasize this, and to pave
the way for a more generalized fn to be added in the future.

rcgen/src/key_pair.rs

@@ -197,7 +197,7 @@ impl KeyPair {
 	) -> Result<Self, Error> {
 		let private_key = pem::parse(pem_str)._err()?;
 		let private_key_der: &[_] = private_key.contents();
-		Self::from_der_and_sign_algo(&PrivatePkcs8KeyDer::from(private_key_der), alg)
+		Self::from_pkcs8_der_and_sign_algo(&PrivatePkcs8KeyDer::from(private_key_der), alg)
 	}
 
 	/// Obtains the key pair from a DER formatted key using the specified [`SignatureAlgorithm`]
@@ -215,7 +215,7 @@ impl KeyPair {
 	/// [`rustls_pemfile::private_key()`]: https://docs.rs/rustls-pemfile/latest/rustls_pemfile/fn.private_key.html
 	/// [`PrivateKeyDer`]: https://docs.rs/rustls-pki-types/latest/rustls_pki_types/enum.PrivateKeyDer.html
 	#[cfg(feature = "crypto")]
-	pub fn from_der_and_sign_algo(
+	pub fn from_pkcs8_der_and_sign_algo(
 		pkcs8: &PrivatePkcs8KeyDer<'_>,
 		alg: &'static SignatureAlgorithm,
 	) -> Result<Self, Error> {

rustls-cert-gen/src/cert.rs

@@ -239,7 +239,7 @@ impl KeyPairAlgorithm {
 				let pkcs8_bytes =
 					Ed25519KeyPair::generate_pkcs8(&rng).or(Err(rcgen::Error::RingUnspecified))?;
 
-				rcgen::KeyPair::from_der_and_sign_algo(&pkcs8_bytes.as_ref().into(), alg)
+				rcgen::KeyPair::from_pkcs8_der_and_sign_algo(&pkcs8_bytes.as_ref().into(), alg)
 			},
 			KeyPairAlgorithm::EcdsaP256 => {
 				use ring::signature::EcdsaKeyPair;
@@ -250,7 +250,7 @@ impl KeyPairAlgorithm {
 				let pkcs8_bytes =
 					EcdsaKeyPair::generate_pkcs8(&ECDSA_P256_SHA256_ASN1_SIGNING, &rng)
 						.or(Err(rcgen::Error::RingUnspecified))?;
-				rcgen::KeyPair::from_der_and_sign_algo(&pkcs8_bytes.as_ref().into(), alg)
+				rcgen::KeyPair::from_pkcs8_der_and_sign_algo(&pkcs8_bytes.as_ref().into(), alg)
 			},
 			KeyPairAlgorithm::EcdsaP384 => {
 				use ring::signature::EcdsaKeyPair;
@@ -262,7 +262,7 @@ impl KeyPairAlgorithm {
 					EcdsaKeyPair::generate_pkcs8(&ECDSA_P384_SHA384_ASN1_SIGNING, &rng)
 						.or(Err(rcgen::Error::RingUnspecified))?;
 
-				rcgen::KeyPair::from_der_and_sign_algo(&pkcs8_bytes.as_ref().into(), alg)
+				rcgen::KeyPair::from_pkcs8_der_and_sign_algo(&pkcs8_bytes.as_ref().into(), alg)
 			},
 		}
 	}