1 files changed, 125 insertions, 0 deletions
diff --git a/src/cryptography/hazmat/primitives/ciphers/modes.py b/src/cryptography/hazmat/primitives/ciphers/modes.py
new file mode 100644
index 00000000..d995b876
--- /dev/null
+++ b/src/cryptography/hazmat/primitives/ciphers/modes.py
@@ -0,0 +1,125 @@
+# 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
+
+from cryptography import utils
+from cryptography.hazmat.primitives import interfaces
+
+
+def _check_iv_length(self, algorithm):
+    if len(self.initialization_vector) * 8 != algorithm.block_size:
+        raise ValueError("Invalid IV size ({0}) for {1}.".format(
+            len(self.initialization_vector), self.name
+        ))
+
+
+@utils.register_interface(interfaces.Mode)
+@utils.register_interface(interfaces.ModeWithInitializationVector)
+class CBC(object):
+    name = "CBC"
+
+    def __init__(self, initialization_vector):
+        self._initialization_vector = initialization_vector
+
+    initialization_vector = utils.read_only_property("_initialization_vector")
+    validate_for_algorithm = _check_iv_length
+
+
+@utils.register_interface(interfaces.Mode)
+class ECB(object):
+    name = "ECB"
+
+    def validate_for_algorithm(self, algorithm):
+        pass
+
+
+@utils.register_interface(interfaces.Mode)
+@utils.register_interface(interfaces.ModeWithInitializationVector)
+class OFB(object):
+    name = "OFB"
+
+    def __init__(self, initialization_vector):
+        self._initialization_vector = initialization_vector
+
+    initialization_vector = utils.read_only_property("_initialization_vector")
+    validate_for_algorithm = _check_iv_length
+
+
+@utils.register_interface(interfaces.Mode)
+@utils.register_interface(interfaces.ModeWithInitializationVector)
+class CFB(object):
+    name = "CFB"
+
+    def __init__(self, initialization_vector):
+        self._initialization_vector = initialization_vector
+
+    initialization_vector = utils.read_only_property("_initialization_vector")
+    validate_for_algorithm = _check_iv_length
+
+
+@utils.register_interface(interfaces.Mode)
+@utils.register_interface(interfaces.ModeWithInitializationVector)
+class CFB8(object):
+    name = "CFB8"
+
+    def __init__(self, initialization_vector):
+        self._initialization_vector = initialization_vector
+
+    initialization_vector = utils.read_only_property("_initialization_vector")
+    validate_for_algorithm = _check_iv_length
+
+
+@utils.register_interface(interfaces.Mode)
+@utils.register_interface(interfaces.ModeWithNonce)
+class CTR(object):
+    name = "CTR"
+
+    def __init__(self, nonce):
+        self._nonce = nonce
+
+    nonce = utils.read_only_property("_nonce")
+
+    def validate_for_algorithm(self, algorithm):
+        if len(self.nonce) * 8 != algorithm.block_size:
+            raise ValueError("Invalid nonce size ({0}) for {1}.".format(
+                len(self.nonce), self.name
+            ))
+
+
+@utils.register_interface(interfaces.Mode)
+@utils.register_interface(interfaces.ModeWithInitializationVector)
+@utils.register_interface(interfaces.ModeWithAuthenticationTag)
+class GCM(object):
+    name = "GCM"
+
+    def __init__(self, initialization_vector, tag=None, min_tag_length=16):
+        # len(initialization_vector) must in [1, 2 ** 64), but it's impossible
+        # to actually construct a bytes object that large, so we don't check
+        # for it
+        if min_tag_length < 4:
+            raise ValueError("min_tag_length must be >= 4")
+        if tag is not None and len(tag) < min_tag_length:
+            raise ValueError(
+                "Authentication tag must be {0} bytes or longer.".format(
+                    min_tag_length)
+            )
+
+        self._initialization_vector = initialization_vector
+        self._tag = tag
+
+    tag = utils.read_only_property("_tag")
+    initialization_vector = utils.read_only_property("_initialization_vector")
+
+    def validate_for_algorithm(self, algorithm):
+        pass