Cleanup serialize (#5149)

* Additional tests for public/private_bytes

They expose few places that raise TypeError and AssertionError!
before, and ValueError later.

* Cleanup of private_bytes() backend

Also pass key itself down to backend.

* Cleanup of public_bytes() backend

* Test handling of unsupported key type

1 files changed, 2 insertions, 6 deletions

diff --git a/src/cryptography/hazmat/backends/openssl/dsa.py b/src/cryptography/hazmat/backends/openssl/dsa.py
index de61f089..79142bf6 100644
--- a/src/cryptography/hazmat/backends/openssl/dsa.py
+++ b/src/cryptography/hazmat/backends/openssl/dsa.py
@@ -10,7 +10,7 @@ from cryptography.hazmat.backends.openssl.utils import (
     _calculate_digest_and_algorithm, _check_not_prehashed,
     _warn_sign_verify_deprecated
 )
-from cryptography.hazmat.primitives import hashes, serialization
+from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.asymmetric import (
     AsymmetricSignatureContext, AsymmetricVerificationContext, dsa
 )
@@ -183,6 +183,7 @@ class _DSAPrivateKey(object):
             encoding,
             format,
             encryption_algorithm,
+            self,
             self._evp_pkey,
             self._dsa_cdata
         )
@@ -248,11 +249,6 @@ class _DSAPublicKey(object):
         return _DSAParameters(self._backend, dsa_cdata)
 
     def public_bytes(self, encoding, format):
-        if format is serialization.PublicFormat.PKCS1:
-            raise ValueError(
-                "DSA public keys do not support PKCS1 serialization"
-            )
-
         return self._backend._public_key_bytes(
             encoding,
             format,