support RSA public key serialization

2 files changed, 37 insertions, 2 deletions

diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py
index 42dcc0fb..f33aba95 100644
--- a/src/cryptography/hazmat/backends/openssl/backend.py
+++ b/src/cryptography/hazmat/backends/openssl/backend.py
@@ -1184,6 +1184,32 @@ class Backend(object):
         assert res == 1
         return self._read_mem_bio(bio)
 
+    def _public_key_bytes(self, encoding, format, pkcs1_write_func, evp_pkey,
+                          cdata):
+        if not isinstance(encoding, serialization.Encoding):
+            raise TypeError("encoding must be an item from the Encoding enum")
+
+        if not isinstance(format, serialization.PublicFormat):
+            raise TypeError(
+                "format must be an item from the PublicFormat enum"
+            )
+
+        # This is a temporary check until we land DER serialization.
+        if encoding is not serialization.Encoding.PEM:
+            raise ValueError("Only PEM encoding is supported by this backend")
+
+        if format is serialization.PublicFormat.SubjectPublicKeyInfo:
+            write_bio = self._lib.PEM_write_bio_PUBKEY
+            key = evp_pkey
+        elif format is serialization.PublicFormat.PKCS1:
+            write_bio = pkcs1_write_func
+            key = cdata
+
+        bio = self._create_mem_bio()
+        res = write_bio(bio, key)
+        assert res == 1
+        return self._read_mem_bio(bio)
+
 
 class GetCipherByName(object):
     def __init__(self, fmt):
diff --git a/src/cryptography/hazmat/backends/openssl/rsa.py b/src/cryptography/hazmat/backends/openssl/rsa.py
index 0470c3fd..25168c2f 100644
--- a/src/cryptography/hazmat/backends/openssl/rsa.py
+++ b/src/cryptography/hazmat/backends/openssl/rsa.py
@@ -19,7 +19,7 @@ from cryptography.hazmat.primitives.asymmetric.padding import (
 )
 from cryptography.hazmat.primitives.asymmetric.rsa import (
     RSAPrivateKeyWithNumbers, RSAPrivateKeyWithSerialization,
-    RSAPublicKeyWithNumbers
+    RSAPublicKeyWithSerialization
 )
 
 
@@ -572,7 +572,7 @@ class _RSAPrivateKey(object):
         )
 
 
-@utils.register_interface(RSAPublicKeyWithNumbers)
+@utils.register_interface(RSAPublicKeyWithSerialization)
 class _RSAPublicKey(object):
     def __init__(self, backend, rsa_cdata):
         self._backend = backend
@@ -604,3 +604,12 @@ class _RSAPublicKey(object):
             e=self._backend._bn_to_int(self._rsa_cdata.e),
             n=self._backend._bn_to_int(self._rsa_cdata.n),
         )
+
+    def public_bytes(self, encoding, format):
+        return self._backend._public_key_bytes(
+            encoding,
+            format,
+            self._backend._lib.PEM_write_bio_RSAPublicKey,
+            self._evp_pkey,
+            self._rsa_cdata
+        )