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
diff --git a/docs/development/test-vectors.rst b/docs/development/test-vectors.rst
index 15fe2d2..f9f865e 100644
--- a/docs/development/test-vectors.rst
+++ b/docs/development/test-vectors.rst
@@ -110,6 +110,20 @@
``vectors/cryptography_vectors/asymmetric/DH/dhpub.der`` contains
are the above parameters and keys in DER format.
+* ``vectors/cryptography_vectors/asymmetric/DH/dhp_rfc5114_2.pem``,
+ ``vectors/cryptography_vectors/asymmetric/DH/dhkey_rfc5114_2.pem`` and
+ ``vectors/cryptography_vectors/asymmetric/DH/dhpub_rfc5114_2.pem`` contains
+ Diffie-Hellman parameters and key respectively. The keys were
+ generated using OpenSSL following `DHKE`_ guide. When creating the
+ parameters we added the `-pkeyopt dh_rfc5114:2` option to use
+ RFC5114 2048 bit DH parameters with 224 bit subgroup.
+ ``vectors/cryptography_vectors/asymmetric/DH/dhkey_rfc5114_2.txt`` contains
+ all parameter in text.
+ ``vectors/cryptography_vectors/asymmetric/DH/dhp_rfc5114_2.der``,
+ ``vectors/cryptography_vectors/asymmetric/DH/dhkey_rfc5114_2.der`` and
+ ``vectors/cryptography_vectors/asymmetric/DH/dhpub_rfc5114_2.der`` contains
+ are the above parameters and keys in DER format.
+
X.509
~~~~~
diff --git a/docs/hazmat/backends/interfaces.rst b/docs/hazmat/backends/interfaces.rst
index 87fc6ab..4f15d5c 100644
--- a/docs/hazmat/backends/interfaces.rst
+++ b/docs/hazmat/backends/interfaces.rst
@@ -666,14 +666,23 @@
:raises cryptography.exceptions.UnsupportedAlgorithm: This is raised
when any backend specific criteria are not met.
- .. method:: dh_parameters_supported(p, g)
+ .. method:: dh_parameters_supported(p, g, q=None)
:param int p: The p value of the DH key.
:param int g: The g value of the DH key.
- :returns: ``True`` if the given values of ``p`` and ``g`` are supported
- by this backend, otherwise ``False``.
+ :param int q: The q value of the DH key.
+
+ :returns: ``True`` if the given values of ``p``, ``g`` and ``q``
+ are supported by this backend, otherwise ``False``.
+
+ .. versionadded:: 1.8
+
+ .. method:: dh_x942_serialization_supported()
+
+ :returns: True if serialization of DH objects with
+ subgroup order (q) is supported by this backend.
.. class:: ScryptBackend
diff --git a/docs/hazmat/primitives/asymmetric/dh.rst b/docs/hazmat/primitives/asymmetric/dh.rst
index 73e534e..759b265 100644
--- a/docs/hazmat/primitives/asymmetric/dh.rst
+++ b/docs/hazmat/primitives/asymmetric/dh.rst
@@ -223,7 +223,7 @@
Numbers
~~~~~~~
-.. class:: DHParameterNumbers(p, g)
+.. class:: DHParameterNumbers(p, g, q=None)
.. versionadded:: 0.8
@@ -239,7 +239,15 @@
:type: int
- The generator value. Must be 2 or 5.
+ The generator value. Must be 2 or 5 (Unless q is given).
+
+ .. attribute:: q
+
+ .. versionadded:: 1.8
+
+ :type: int
+
+ p subgroup order value.
.. class:: DHPrivateNumbers(x, public_numbers)