DH subgroup order (q) (#3369)

* Support DH q (subgroup order)

* Change RFC5114.txt to NIST format

* Add tests for DH q

* Update docs for DH q

* Fix pep8

* Improve test covergae for DH q

* Create _dh_params_dup that copy q if DHparams_dup don't

On OpenSSL < 1.0.2 DHparams_dup don't copy q. _dh_params_dup
call DHparams_dup and if the version is smaller than 1.0.2
copy q manually

* Copy q manually on libressl

* Add to test vectors serialized RFC5114 2048 bit DH parameters with 224 bit subgroup

* Support serialization of DH with q

* Add tests for serialization of DH with q

* Support DH serialization with q only if Cryptography_HAS_EVP_PKEY_DHX is true

* Raise exception when trying to serialize DH X9.42 when not supported

* raise unsupported key type when deserilizing DH X9.42 if not supported

* pep8 fixes

* Fix test_serialization

* Add dhx_serialization_supported method to DHBacked

* document q in dh_parameters_supported

* Rename dhx_serialization_supported to dh_x942_serialization_supported

1 files changed, 14 insertions, 7 deletions

diff --git a/tests/hazmat/primitives/test_serialization.py b/tests/hazmat/primitives/test_serialization.py
index dad056c6..bc16b5f8 100644
--- a/tests/hazmat/primitives/test_serialization.py
+++ b/tests/hazmat/primitives/test_serialization.py
@@ -236,10 +236,12 @@ class TestDERSerialization(object):
         """).encode()
         bad_der = base64.b64decode(b"".join(key_data.splitlines()))
 
-        with pytest.raises(ValueError):
+        with raises_unsupported_algorithm(
+                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM):
             load_pem_private_key(bad_der, None, backend)
 
-        with pytest.raises(ValueError):
+        with raises_unsupported_algorithm(
+                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM):
             load_pem_private_key(
                 bad_der, b"this password will not be used", backend
             )
@@ -575,12 +577,14 @@ class TestPEMSerialization(object):
     def test_wrong_private_format(self, backend):
         key_data = b"---- NOT A KEY ----\n"
 
-        with pytest.raises(ValueError):
+        with raises_unsupported_algorithm(
+                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM):
             load_pem_private_key(
                 key_data, None, backend
             )
 
-        with pytest.raises(ValueError):
+        with raises_unsupported_algorithm(
+                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM):
             load_pem_private_key(
                 key_data, b"this password will not be used", backend
             )
@@ -588,7 +592,8 @@ class TestPEMSerialization(object):
     def test_wrong_public_format(self, backend):
         key_data = b"---- NOT A KEY ----\n"
 
-        with pytest.raises(ValueError):
+        with raises_unsupported_algorithm(
+                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM):
             load_pem_public_key(key_data, backend)
 
     def test_corrupt_traditional_format(self, backend):
@@ -720,12 +725,14 @@ class TestPEMSerialization(object):
 
         password = b"this password is wrong"
 
-        with pytest.raises(ValueError):
+        with raises_unsupported_algorithm(
+                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM):
             load_pem_private_key(
                 key_data, None, backend
             )
 
-        with pytest.raises(ValueError):
+        with raises_unsupported_algorithm(
+                _Reasons.UNSUPPORTED_PUBLIC_KEY_ALGORITHM):
             load_pem_private_key(
                 key_data, password, backend
             )