Add test cases for length checking and already finalized.

1 files changed, 85 insertions, 0 deletions

diff --git a/tests/hazmat/primitives/test_hkdf.py b/tests/hazmat/primitives/test_hkdf.py
new file mode 100644
index 00000000..3d9dffda
--- /dev/null
+++ b/tests/hazmat/primitives/test_hkdf.py
@@ -0,0 +1,85 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import absolute_import, division, print_function
+
+import pytest
+
+from cryptography import exceptions
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.kdf.hkdf import HKDF
+
+
+@pytest.mark.hash
+class TestHKDF(object):
+    def test_length_limit(self, backend):
+        big_length = 255 * (hashes.SHA256().digest_size // 8) + 1
+
+        with pytest.raises(ValueError):
+            HKDF(
+                hashes.SHA256(),
+                big_length,
+                salt=None,
+                info=None,
+                backend=backend
+            )
+
+    def test_already_finalized(self, backend):
+        hkdf = HKDF(
+            hashes.SHA256(),
+            16,
+            salt=None,
+            info=None,
+            backend=backend
+        )
+
+        hkdf.derive('\x01' * 16)
+
+        with pytest.raises(exceptions.AlreadyFinalized):
+            hkdf.derive('\x02' * 16)
+
+        hkdf = HKDF(
+            hashes.SHA256(),
+            16,
+            salt=None,
+            info=None,
+            backend=backend
+        )
+
+        hkdf.verify('\x01' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')
+
+        with pytest.raises(exceptions.AlreadyFinalized):
+            hkdf.verify('\x02' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')
+
+    def test_verify(self, backend):
+        hkdf = HKDF(
+            hashes.SHA256(),
+            16,
+            salt=None,
+            info=None,
+            backend=backend
+        )
+
+        hkdf.verify('\x01' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')
+
+    def test_verify_invalid(self, backend):
+        hkdf = HKDF(
+            hashes.SHA256(),
+            16,
+            salt=None,
+            info=None,
+            backend=backend
+        )
+
+        with pytest.raises(exceptions.InvalidKey):
+            hkdf.verify('\x02' * 16, 'gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u')