serialize DSA private keys

2 files changed, 38 insertions, 7 deletions

diff --git a/src/cryptography/hazmat/backends/openssl/dsa.py b/src/cryptography/hazmat/backends/openssl/dsa.py
index d2972e4a..8d02e492 100644
--- a/src/cryptography/hazmat/backends/openssl/dsa.py
+++ b/src/cryptography/hazmat/backends/openssl/dsa.py
@@ -11,9 +11,6 @@ from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.asymmetric import (
     AsymmetricSignatureContext, AsymmetricVerificationContext, dsa
 )
-from cryptography.hazmat.primitives.interfaces import (
-    DSAParametersWithNumbers, DSAPrivateKeyWithNumbers, DSAPublicKeyWithNumbers
-)
 
 
 def _truncate_digest_for_dsa(dsa_cdata, digest, backend):
@@ -94,7 +91,7 @@ class _DSASignatureContext(object):
         return self._backend._ffi.buffer(sig_buf)[:buflen[0]]
 
 
-@utils.register_interface(DSAParametersWithNumbers)
+@utils.register_interface(dsa.DSAParametersWithNumbers)
 class _DSAParameters(object):
     def __init__(self, backend, dsa_cdata):
         self._backend = backend
@@ -111,7 +108,7 @@ class _DSAParameters(object):
         return self._backend.generate_dsa_private_key(self)
 
 
-@utils.register_interface(DSAPrivateKeyWithNumbers)
+@utils.register_interface(dsa.DSAPrivateKeyWithSerialization)
 class _DSAPrivateKey(object):
     def __init__(self, backend, dsa_cdata):
         self._backend = backend
@@ -159,8 +156,25 @@ class _DSAPrivateKey(object):
         dsa_cdata.g = self._backend._lib.BN_dup(self._dsa_cdata.g)
         return _DSAParameters(self._backend, dsa_cdata)
 
+    def private_bytes(self, encoding, format, encryption_algorithm):
+        evp_pkey = self._backend._lib.EVP_PKEY_new()
+        assert evp_pkey != self._backend._ffi.NULL
+        evp_pkey = self._backend._ffi.gc(
+            evp_pkey, self._backend._lib.EVP_PKEY_free
+        )
+        res = self._backend._lib.EVP_PKEY_set1_DSA(evp_pkey, self._dsa_cdata)
+        assert res == 1
+        return self._backend._private_key_bytes(
+            encoding,
+            format,
+            encryption_algorithm,
+            self._backend._lib.PEM_write_bio_DSAPrivateKey,
+            evp_pkey,
+            self._dsa_cdata
+        )
+
 
-@utils.register_interface(DSAPublicKeyWithNumbers)
+@utils.register_interface(dsa.DSAPublicKeyWithNumbers)
 class _DSAPublicKey(object):
     def __init__(self, backend, dsa_cdata):
         self._backend = backend
diff --git a/src/cryptography/hazmat/primitives/asymmetric/dsa.py b/src/cryptography/hazmat/primitives/asymmetric/dsa.py
index 58058df9..084686e4 100644
--- a/src/cryptography/hazmat/primitives/asymmetric/dsa.py
+++ b/src/cryptography/hazmat/primitives/asymmetric/dsa.py
@@ -57,13 +57,30 @@ class DSAPrivateKey(object):
 
 
 @six.add_metaclass(abc.ABCMeta)
-class DSAPrivateKeyWithNumbers(DSAPrivateKey):
+class DSAPrivateKeyWithSerialization(DSAPrivateKey):
     @abc.abstractmethod
     def private_numbers(self):
         """
         Returns a DSAPrivateNumbers.
         """
 
+    @abc.abstractmethod
+    def private_bytes(self, encoding, format, encryption_algorithm):
+        """
+        Returns the key serialized as bytes.
+        """
+
+
+DSAPrivateKeyWithNumbers = utils.deprecated(
+    DSAPrivateKeyWithSerialization,
+    __name__,
+    (
+        "The DSAPrivateKeyWithNumbers interface has been renamed to "
+        "DSAPrivateKeyWithSerialization"
+    ),
+    utils.DeprecatedIn08
+)
+
 
 @six.add_metaclass(abc.ABCMeta)
 class DSAPublicKey(object):