Merge pull request #705 from NicholasTanz/renameFromPem

#615 - rename _from_pem to _crypto_key

securesystemslib/signer/_key.py

@@ -238,12 +238,8 @@ def from_dict(cls, keyid: str, key_dict: Dict[str, Any]) -> "SSlibKey":
     def to_dict(self) -> Dict[str, Any]:
         return self._to_dict()
 
-    def _from_pem(self) -> "PublicKeyTypes":
-        """Helper to load public key instance from PEM-formatted keyval.
-
-        # FIXME: Sounds like it's an SSlibKey factory, but isn't. Should think
-        of a better name or refactor _verify!
-        """
+    def _crypto_key(self) -> "PublicKeyTypes":
+        """Helper to get a `cryptography` public key for this SSlibKey."""
         public_bytes = self.keyval["public"].encode("utf-8")
         return load_pem_public_key(public_bytes)
 
@@ -376,7 +372,7 @@ def _verify(self, signature: bytes, data: bytes) -> None:
                 "rsa-pkcs1v15-sha384",
                 "rsa-pkcs1v15-sha512",
             ]:
-                key = cast(RSAPublicKey, self._from_pem())
+                key = cast(RSAPublicKey, self._crypto_key())
                 padding_name, hash_name = self.scheme.split("-")[1:]
                 hash_algorithm = self._get_hash_algorithm(hash_name)
                 padding = self._get_rsa_padding(padding_name, hash_algorithm)
@@ -386,7 +382,7 @@ def _verify(self, signature: bytes, data: bytes) -> None:
                 "ecdsa-sha2-nistp256",
                 "ecdsa-sha2-nistp384",
             ]:
-                key = cast(EllipticCurvePublicKey, self._from_pem())
+                key = cast(EllipticCurvePublicKey, self._crypto_key())
                 hash_name = f"sha{self.scheme[-3:]}"
                 hash_algorithm = self._get_hash_algorithm(hash_name)
                 signature_algorithm = ECDSA(hash_algorithm)