Merge pull request #490 from dreid/hkdf

HKDF - RFC5869 implementation.

3 files changed, 259 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..e3e2a9df
--- /dev/null
+++ b/tests/hazmat/primitives/test_hkdf.py
@@ -0,0 +1,147 @@
+# 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 six
+
+import pytest
+
+from cryptography.exceptions import AlreadyFinalized, InvalidKey
+from cryptography.hazmat.primitives import hashes
+from cryptography.hazmat.primitives.kdf.hkdf import HKDF
+
+
+@pytest.mark.hmac
+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(b"\x01" * 16)
+
+        with pytest.raises(AlreadyFinalized):
+            hkdf.derive(b"\x02" * 16)
+
+        hkdf = HKDF(
+            hashes.SHA256(),
+            16,
+            salt=None,
+            info=None,
+            backend=backend
+        )
+
+        hkdf.verify(b"\x01" * 16, b"gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u")
+
+        with pytest.raises(AlreadyFinalized):
+            hkdf.verify(b"\x02" * 16, b"gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u")
+
+        hkdf = HKDF(
+            hashes.SHA256(),
+            16,
+            salt=None,
+            info=None,
+            backend=backend
+        )
+
+    def test_verify(self, backend):
+        hkdf = HKDF(
+            hashes.SHA256(),
+            16,
+            salt=None,
+            info=None,
+            backend=backend
+        )
+
+        hkdf.verify(b"\x01" * 16, b"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(InvalidKey):
+            hkdf.verify(b"\x02" * 16, b"gJ\xfb{\xb1Oi\xc5sMC\xb7\xe4@\xf7u")
+
+    def test_unicode_typeerror(self, backend):
+        with pytest.raises(TypeError):
+            HKDF(
+                hashes.SHA256(),
+                16,
+                salt=six.u("foo"),
+                info=None,
+                backend=backend
+            )
+
+        with pytest.raises(TypeError):
+            HKDF(
+                hashes.SHA256(),
+                16,
+                salt=None,
+                info=six.u("foo"),
+                backend=backend
+            )
+
+        with pytest.raises(TypeError):
+            hkdf = HKDF(
+                hashes.SHA256(),
+                16,
+                salt=None,
+                info=None,
+                backend=backend
+            )
+
+            hkdf.derive(six.u("foo"))
+
+        with pytest.raises(TypeError):
+            hkdf = HKDF(
+                hashes.SHA256(),
+                16,
+                salt=None,
+                info=None,
+                backend=backend
+            )
+
+            hkdf.verify(six.u("foo"), b"bar")
+
+        with pytest.raises(TypeError):
+            hkdf = HKDF(
+                hashes.SHA256(),
+                16,
+                salt=None,
+                info=None,
+                backend=backend
+            )
+
+            hkdf.verify(b"foo", six.u("bar"))
diff --git a/tests/hazmat/primitives/test_hkdf_vectors.py b/tests/hazmat/primitives/test_hkdf_vectors.py
new file mode 100644
index 00000000..1e67234f
--- /dev/null
+++ b/tests/hazmat/primitives/test_hkdf_vectors.py
@@ -0,0 +1,51 @@
+# 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 os
+
+import pytest
+
+from cryptography.hazmat.primitives import hashes
+
+from .utils import generate_hkdf_test
+from ...utils import load_nist_vectors
+
+
+@pytest.mark.supported(
+    only_if=lambda backend: backend.hmac_supported(hashes.SHA1()),
+    skip_message="Does not support SHA1."
+)
+@pytest.mark.hmac
+class TestHKDFSHA1(object):
+    test_HKDFSHA1 = generate_hkdf_test(
+        load_nist_vectors,
+        os.path.join("KDF"),
+        ["rfc-5869-HKDF-SHA1.txt"],
+        hashes.SHA1()
+    )
+
+
+@pytest.mark.supported(
+    only_if=lambda backend: backend.hmac_supported(hashes.SHA256()),
+    skip_message="Does not support SHA256."
+)
+@pytest.mark.hmac
+class TestHKDFSHA256(object):
+    test_HKDFSHA1 = generate_hkdf_test(
+        load_nist_vectors,
+        os.path.join("KDF"),
+        ["rfc-5869-HKDF-SHA256.txt"],
+        hashes.SHA256()
+    )
diff --git a/tests/hazmat/primitives/utils.py b/tests/hazmat/primitives/utils.py
index 6b1d055d..5a8dc3ab 100644
--- a/tests/hazmat/primitives/utils.py
+++ b/tests/hazmat/primitives/utils.py
@@ -1,11 +1,15 @@
 import binascii
 import os
 
+import itertools
+
 import pytest
 
 from cryptography.hazmat.primitives import hashes, hmac
 from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
 from cryptography.hazmat.primitives.ciphers import Cipher
+from cryptography.hazmat.primitives.kdf.hkdf import HKDF
+
 from cryptography.exceptions import (
     AlreadyFinalized, NotYetFinalized, AlreadyUpdated, InvalidTag,
 )
@@ -297,3 +301,60 @@ def aead_tag_exception_test(backend, cipher_factory, mode_factory):
     )
     with pytest.raises(ValueError):
         cipher.encryptor()
+
+
+def hkdf_derive_test(backend, algorithm, params):
+    hkdf = HKDF(
+        algorithm,
+        int(params["l"]),
+        salt=binascii.unhexlify(params["salt"]) or None,
+        info=binascii.unhexlify(params["info"]) or None,
+        backend=backend
+    )
+
+    okm = hkdf.derive(binascii.unhexlify(params["ikm"]))
+
+    assert okm == binascii.unhexlify(params["okm"])
+
+
+def hkdf_extract_test(backend, algorithm, params):
+    hkdf = HKDF(
+        algorithm,
+        int(params["l"]),
+        salt=binascii.unhexlify(params["salt"]) or None,
+        info=binascii.unhexlify(params["info"]) or None,
+        backend=backend
+    )
+
+    prk = hkdf._extract(binascii.unhexlify(params["ikm"]))
+
+    assert prk == binascii.unhexlify(params["prk"])
+
+
+def hkdf_expand_test(backend, algorithm, params):
+    hkdf = HKDF(
+        algorithm,
+        int(params["l"]),
+        salt=binascii.unhexlify(params["salt"]) or None,
+        info=binascii.unhexlify(params["info"]) or None,
+        backend=backend
+    )
+
+    okm = hkdf._expand(binascii.unhexlify(params["prk"]))
+
+    assert okm == binascii.unhexlify(params["okm"])
+
+
+def generate_hkdf_test(param_loader, path, file_names, algorithm):
+    all_params = _load_all_params(path, file_names, param_loader)
+
+    all_tests = [hkdf_extract_test, hkdf_expand_test, hkdf_derive_test]
+
+    @pytest.mark.parametrize(
+        ("params", "hkdf_test"),
+        itertools.product(all_params, all_tests)
+    )
+    def test_hkdf(self, backend, params, hkdf_test):
+        hkdf_test(backend, algorithm, params)
+
+    return test_hkdf