Blowfish Support

cryptography/hazmat/bindings/openssl/backend.py

@@ -20,7 +20,7 @@
 
 from cryptography.hazmat.primitives import interfaces
 from cryptography.hazmat.primitives.block.ciphers import (
-    AES, Camellia, TripleDES,
+    AES, Blowfish, Camellia, TripleDES,
 )
 from cryptography.hazmat.primitives.block.modes import CBC, CTR, ECB, OFB, CFB
 
@@ -221,6 +221,12 @@ def _register_default_ciphers(self):
                 mode_cls,
                 GetCipherByName("des-ede3-{mode.name}")
             )
+        for mode_cls in [CBC, CFB, OFB, ECB]:
+            self.register_cipher_adapter(
+                Blowfish,
+                mode_cls,
+                GetCipherByName("bf-{mode.name}")
+            )
 
     def create_encrypt_ctx(self, cipher, mode):
         return _CipherContext(self._backend, cipher, mode,

cryptography/hazmat/primitives/block/ciphers.py

@@ -76,3 +76,23 @@ def __init__(self, key):
     @property
     def key_size(self):
         return len(self.key) * 8
+
+
+class Blowfish(object):
+    name = "Blowfish"
+    block_size = 64
+    key_sizes = frozenset(range(32, 449, 8))
+
+    def __init__(self, key):
+        super(Blowfish, self).__init__()
+        self.key = key
+
+        # Verify that the key size matches the expected key size
+        if self.key_size not in self.key_sizes:
+            raise ValueError("Invalid key size ({0}) for {1}".format(
+                self.key_size, self.name
+            ))
+
+    @property
+    def key_size(self):
+        return len(self.key) * 8

docs/hazmat/primitives/symmetric-encryption.rst

@@ -107,6 +107,25 @@ Ciphers
                       ``56`` bits long), they can simply be concatenated to
                       produce the full key. This must be kept secret.
 
+Weak Ciphers
+------------
+
+.. warning::
+
+    These ciphers are considered weak for a variety of reasons. New
+    applications should avoid their use and existing applications should
+    strongly consider migrating away.
+
+.. class:: Blowfish(key)
+
+    Blowfish is a block cipher developed by Bruce Schneier. It is known to be
+    susceptible to attacks when using weak keys. The author has recommended
+    that users of Blowfish move to newer algorithms like
+    :class:`AES`.
+
+    :param bytes key: The secret key, 32-448 bits in length (in increments of
+                      8).  This must be kept secret.
+
 
 Modes
 ~~~~~

tests/hazmat/primitives/test_blowfish.py

@@ -0,0 +1,56 @@
+# 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 binascii
+import os
+
+from cryptography.hazmat.primitives.block import ciphers, modes
+
+from .utils import generate_encrypt_test
+from ...utils import load_nist_vectors_from_file
+
+
+class TestBlowfish(object):
+    test_ECB = generate_encrypt_test(
+        lambda path: load_nist_vectors_from_file(path, "ENCRYPT"),
+        os.path.join("ciphers", "Blowfish"),
+        ["bf-ecb.txt"],
+        lambda key: ciphers.Blowfish(binascii.unhexlify(key)),
+        lambda key: modes.ECB(),
+    )
+
+    test_CBC = generate_encrypt_test(
+        lambda path: load_nist_vectors_from_file(path, "ENCRYPT"),
+        os.path.join("ciphers", "Blowfish"),
+        ["bf-cbc.txt"],
+        lambda key, iv: ciphers.Blowfish(binascii.unhexlify(key)),
+        lambda key, iv: modes.CBC(binascii.unhexlify(iv)),
+    )
+
+    test_OFB = generate_encrypt_test(
+        lambda path: load_nist_vectors_from_file(path, "ENCRYPT"),
+        os.path.join("ciphers", "Blowfish"),
+        ["bf-ofb.txt"],
+        lambda key, iv: ciphers.Blowfish(binascii.unhexlify(key)),
+        lambda key, iv: modes.OFB(binascii.unhexlify(iv)),
+    )
+
+    test_CFB = generate_encrypt_test(
+        lambda path: load_nist_vectors_from_file(path, "ENCRYPT"),
+        os.path.join("ciphers", "Blowfish"),
+        ["bf-cfb.txt"],
+        lambda key, iv: ciphers.Blowfish(binascii.unhexlify(key)),
+        lambda key, iv: modes.CFB(binascii.unhexlify(iv)),
+    )

tests/hazmat/primitives/test_ciphers.py

@@ -18,7 +18,7 @@
 import pytest
 
 from cryptography.hazmat.primitives.block.ciphers import (
-    AES, Camellia, TripleDES,
+    AES, Camellia, TripleDES, Blowfish
 )
 
 
@@ -65,3 +65,16 @@ def test_key_size(self, key):
     def test_invalid_key_size(self):
         with pytest.raises(ValueError):
             TripleDES(binascii.unhexlify(b"0" * 12))
+
+
+class TestBlowfish(object):
+    @pytest.mark.parametrize(("key", "keysize"), [
+        (b"0" * (keysize // 4), keysize) for keysize in range(32, 449, 8)
+    ])
+    def test_key_size(self, key, keysize):
+        cipher = Blowfish(binascii.unhexlify(key))
+        assert cipher.key_size == keysize
+
+    def test_invalid_key_size(self):
+        with pytest.raises(ValueError):
+            Blowfish(binascii.unhexlify(b"0" * 6))

tests/hazmat/primitives/vectors/ciphers/Blowfish/bf-cbc.txt

@@ -0,0 +1,11 @@
+# Reformatted from https://www.schneier.com/code/vectors.txt
+# to look like the NIST vectors
+
+[ENCRYPT]
+
+COUNT = 0
+KEY = 0123456789ABCDEFF0E1D2C3B4A59687
+IV = FEDCBA9876543210
+# this pt is implicitly padded with null bytes for CBC
+PLAINTEXT = 37363534333231204E6F77206973207468652074696D6520666F722000000000
+CIPHERTEXT = 6B77B4D63006DEE605B156E27403979358DEB9E7154616D959F1652BD5FF92CC

tests/hazmat/primitives/vectors/ciphers/Blowfish/bf-cfb.txt

@@ -0,0 +1,10 @@
+# Reformatted from https://www.schneier.com/code/vectors.txt
+# to look like the NIST vectors
+
+[ENCRYPT]
+
+COUNT = 0
+KEY = 0123456789ABCDEFF0E1D2C3B4A59687
+IV = FEDCBA9876543210
+PLAINTEXT = 37363534333231204E6F77206973207468652074696D6520666F722000
+CIPHERTEXT = E73214A2822139CAF26ECF6D2EB9E76E3DA3DE04D1517200519D57A6C3