Merge branch 'master' into block-cipher-decrypt

3 files changed, 79 insertions, 15 deletions

diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index a3198c1a..67d73afb 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -13,11 +13,23 @@
 
 from __future__ import absolute_import, division, print_function
 
+import itertools
 import sys
 
 import cffi
 
 from cryptography.primitives import interfaces
+from cryptography.primitives.block.ciphers import AES, Camellia
+from cryptography.primitives.block.modes import CBC, CTR, ECB, OFB, CFB
+
+
+class GetCipherByName(object):
+    def __init__(self, fmt):
+        self._fmt = fmt
+
+    def __call__(self, api, cipher, mode):
+        cipher_name = self._fmt.format(cipher=cipher, mode=mode).lower()
+        return api.lib.EVP_get_cipherbyname(cipher_name.encode("ascii"))
 
 
 class API(object):
@@ -35,6 +47,7 @@ class API(object):
         "engine",
         "err",
         "evp",
+        "hmac",
         "nid",
         "opensslv",
         "pem",
@@ -86,6 +99,9 @@ class API(object):
         self.lib.OpenSSL_add_all_algorithms()
         self.lib.SSL_load_error_strings()
 
+        self._cipher_registry = {}
+        self._register_default_ciphers()
+
     def openssl_version_text(self):
         """
         Friendly string name of linked OpenSSL.
@@ -94,9 +110,31 @@ class API(object):
         """
         return self.ffi.string(self.lib.OPENSSL_VERSION_TEXT).decode("ascii")
 
-    def supports_cipher(self, ciphername):
-        return (self.ffi.NULL !=
-                self.lib.EVP_get_cipherbyname(ciphername.encode("ascii")))
+    def supports_cipher(self, cipher, mode):
+        try:
+            adapter = self._cipher_registry[type(cipher), type(mode)]
+        except KeyError:
+            return False
+        evp_cipher = adapter(self, cipher, mode)
+        return self.ffi.NULL != evp_cipher
+
+    def register_cipher_adapter(self, cipher_cls, mode_cls, adapter):
+        if (cipher_cls, mode_cls) in self._cipher_registry:
+            raise ValueError("Duplicate registration for: {0} {1}".format(
+                cipher_cls, mode_cls)
+            )
+        self._cipher_registry[cipher_cls, mode_cls] = adapter
+
+    def _register_default_ciphers(self):
+        for cipher_cls, mode_cls in itertools.product(
+            [AES, Camellia],
+            [CBC, CTR, ECB, OFB, CFB],
+        ):
+            self.register_cipher_adapter(
+                cipher_cls,
+                mode_cls,
+                GetCipherByName("{cipher.name}-{cipher.key_size}-{mode.name}")
+            )
 
     def create_block_cipher_encrypt_context(self, cipher, mode):
         ctx, evp, iv_nonce = self._create_block_cipher_context(cipher, mode)
@@ -119,15 +157,11 @@ class API(object):
         return ctx
 
     def _create_block_cipher_context(self, cipher, mode):
-        ctx = self.ffi.new("EVP_CIPHER_CTX *")
-        res = self.lib.EVP_CIPHER_CTX_init(ctx)
-        assert res != 0
-        ctx = self.ffi.gc(ctx, self.lib.EVP_CIPHER_CTX_cleanup)
-        # TODO: compute name using a better algorithm
-        ciphername = "{0}-{1}-{2}".format(
-            cipher.name, cipher.key_size, mode.name
-        ).lower()
-        evp_cipher = self.lib.EVP_get_cipherbyname(ciphername.encode("ascii"))
+        ctx = self.lib.EVP_CIPHER_CTX_new()
+        ctx = self.ffi.gc(ctx, self.lib.EVP_CIPHER_CTX_free)
+        evp_cipher = self._cipher_registry[type(cipher), type(mode)](
+            self, cipher, mode
+        )
         assert evp_cipher != self.ffi.NULL
         if isinstance(mode, interfaces.ModeWithInitializationVector):
             iv_nonce = mode.initialization_vector
diff --git a/cryptography/bindings/openssl/hmac.py b/cryptography/bindings/openssl/hmac.py
new file mode 100644
index 00000000..e97ac35e
--- /dev/null
+++ b/cryptography/bindings/openssl/hmac.py
@@ -0,0 +1,32 @@
+# 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.
+
+INCLUDES = """
+#include <openssl/hmac.h>
+"""
+
+TYPES = """
+typedef struct { ...; } HMAC_CTX;
+"""
+
+FUNCTIONS = """
+void HMAC_CTX_init(HMAC_CTX *);
+void HMAC_CTX_cleanup(HMAC_CTX *);
+int HMAC_Init_ex(HMAC_CTX *, const void *, int, const EVP_MD *, ENGINE *);
+int HMAC_Update(HMAC_CTX *, const unsigned char *, size_t);
+int HMAC_Final(HMAC_CTX *, unsigned char *, unsigned int *);
+int HMAC_CTX_copy(HMAC_CTX *, HMAC_CTX *);
+"""
+
+MACROS = """
+"""
diff --git a/cryptography/primitives/block/base.py b/cryptography/primitives/block/base.py
index 14704ffe..e625dc7c 100644
--- a/cryptography/primitives/block/base.py
+++ b/cryptography/primitives/block/base.py
@@ -13,15 +13,13 @@
 
 from __future__ import absolute_import, division, print_function
 
-from cryptography.bindings import _default_api
-
 
 class BlockCipher(object):
     def __init__(self, cipher, mode, api=None):
         super(BlockCipher, self).__init__()
 
         if api is None:
-            api = _default_api
+            from cryptography.bindings import _default_api as api
 
         self.cipher = cipher
         self.mode = mode