Brainpool curves (#4129)

* added brainpool ec-curves key_length >= 256bit

* limit brainpool curves to the set that appear required + docs

* oops

* typos all around me

* add brainpool ECDH kex tests

* switch to using rfc 7027 vectors

* review feedback

* empty commits are the best

1 files changed, 28 insertions, 1 deletions

diff --git a/tests/hazmat/primitives/test_ec.py b/tests/hazmat/primitives/test_ec.py
index 02b1cdc6..1b491a10 100644
--- a/tests/hazmat/primitives/test_ec.py
+++ b/tests/hazmat/primitives/test_ec.py
@@ -26,7 +26,7 @@ from .fixtures_ec import EC_KEY_SECP384R1
 from ...doubles import DummyKeySerializationEncryption
 from ...utils import (
     load_fips_ecdsa_key_pair_vectors, load_fips_ecdsa_signing_vectors,
-    load_kasvs_ecdh_vectors, load_vectors_from_file,
+    load_kasvs_ecdh_vectors, load_nist_vectors, load_vectors_from_file,
     raises_unsupported_algorithm
 )
 
@@ -1101,6 +1101,33 @@ class TestECDH(object):
         else:
             assert z == vector['Z']
 
+    @pytest.mark.parametrize(
+        "vector",
+        load_vectors_from_file(
+            os.path.join("asymmetric", "ECDH", "brainpool.txt"),
+            load_nist_vectors
+        )
+    )
+    def test_brainpool_kex(self, backend, vector):
+        curve = ec._CURVE_TYPES[vector['curve'].decode('ascii')]
+        _skip_exchange_algorithm_unsupported(backend, ec.ECDH(), curve)
+        key = ec.EllipticCurvePrivateNumbers(
+            int(vector['da'], 16),
+            ec.EllipticCurvePublicNumbers(
+                int(vector['x_qa'], 16), int(vector['y_qa'], 16), curve()
+            )
+        ).private_key(backend)
+        peer = ec.EllipticCurvePrivateNumbers(
+            int(vector['db'], 16),
+            ec.EllipticCurvePublicNumbers(
+                int(vector['x_qb'], 16), int(vector['y_qb'], 16), curve()
+            )
+        ).private_key(backend)
+        shared_secret = key.exchange(ec.ECDH(), peer.public_key())
+        assert shared_secret == binascii.unhexlify(vector["x_z"])
+        shared_secret_2 = peer.exchange(ec.ECDH(), key.public_key())
+        assert shared_secret_2 == binascii.unhexlify(vector["x_z"])
+
     def test_exchange_unsupported_algorithm(self, backend):
         _skip_curve_unsupported(backend, ec.SECP256R1())