Merge branch 'master' into fernet

29 files changed, 240 insertions, 45 deletions

diff --git a/cryptography/exceptions.py b/cryptography/exceptions.py
new file mode 100644
index 00000000..391bed82
--- /dev/null
+++ b/cryptography/exceptions.py
@@ -0,0 +1,16 @@
+# 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.
+
+
+class UnsupportedAlgorithm(Exception):
+    pass
diff --git a/cryptography/hazmat/bindings/openssl/asn1.py b/cryptography/hazmat/bindings/openssl/asn1.py
index 5bd72e9a..719a523c 100644
--- a/cryptography/hazmat/bindings/openssl/asn1.py
+++ b/cryptography/hazmat/bindings/openssl/asn1.py
@@ -119,3 +119,6 @@ long ASN1_INTEGER_get(ASN1_INTEGER *);
 
 BIGNUM *ASN1_INTEGER_to_BN(ASN1_INTEGER *, BIGNUM *);
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/backend.py b/cryptography/hazmat/bindings/openssl/backend.py
index fc73dd39..0c3d22d5 100644
--- a/cryptography/hazmat/bindings/openssl/backend.py
+++ b/cryptography/hazmat/bindings/openssl/backend.py
@@ -18,11 +18,14 @@ import sys
 
 import cffi
 
+from cryptography.exceptions import UnsupportedAlgorithm
 from cryptography.hazmat.primitives import interfaces
-from cryptography.hazmat.primitives.block.ciphers import (
+from cryptography.hazmat.primitives.ciphers.algorithms import (
     AES, Blowfish, Camellia, CAST5, TripleDES,
 )
-from cryptography.hazmat.primitives.block.modes import CBC, CTR, ECB, OFB, CFB
+from cryptography.hazmat.primitives.ciphers.modes import (
+    CBC, CTR, ECB, OFB, CFB
+)
 
 
 class Backend(object):
@@ -54,29 +57,45 @@ class Backend(object):
         "x509v3",
     ]
 
+    ffi = None
+    lib = None
+
     def __init__(self):
-        self.ffi = cffi.FFI()
+        self._ensure_ffi_initialized()
+
+        self.ciphers = Ciphers(self)
+        self.hashes = Hashes(self)
+        self.hmacs = HMACs(self)
+
+    @classmethod
+    def _ensure_ffi_initialized(cls):
+        if cls.ffi is not None and cls.lib is not None:
+            return
+
+        ffi = cffi.FFI()
         includes = []
         functions = []
         macros = []
-        for name in self._modules:
+        customizations = []
+        for name in cls._modules:
             module_name = "cryptography.hazmat.bindings.openssl." + name
             __import__(module_name)
             module = sys.modules[module_name]
 
-            self.ffi.cdef(module.TYPES)
+            ffi.cdef(module.TYPES)
 
             macros.append(module.MACROS)
             functions.append(module.FUNCTIONS)
             includes.append(module.INCLUDES)
+            customizations.append(module.CUSTOMIZATIONS)
 
         # loop over the functions & macros after declaring all the types
         # so we can set interdependent types in different files and still
         # have them all defined before we parse the funcs & macros
         for func in functions:
-            self.ffi.cdef(func)
+            ffi.cdef(func)
         for macro in macros:
-            self.ffi.cdef(macro)
+            ffi.cdef(macro)
 
         # We include functions here so that if we got any of their definitions
         # wrong, the underlying C compiler will explode. In C you are allowed
@@ -86,17 +105,15 @@ class Backend(object):
         # is legal, but the following will fail to compile:
         #   int foo(int);
         #   int foo(short);
-        self.lib = self.ffi.verify(
-            source="\n".join(includes + functions),
+        lib = ffi.verify(
+            source="\n".join(includes + functions + customizations),
             libraries=["crypto", "ssl"],
         )
 
-        self.lib.OpenSSL_add_all_algorithms()
-        self.lib.SSL_load_error_strings()
-
-        self.ciphers = Ciphers(self)
-        self.hashes = Hashes(self)
-        self.hmacs = HMACs(self)
+        cls.ffi = ffi
+        cls.lib = lib
+        cls.lib.OpenSSL_add_all_algorithms()
+        cls.lib.SSL_load_error_strings()
 
     def openssl_version_text(self):
         """
@@ -128,10 +145,15 @@ class _CipherContext(object):
         ctx = self._backend.ffi.gc(ctx, self._backend.lib.EVP_CIPHER_CTX_free)
 
         registry = self._backend.ciphers._cipher_registry
-        evp_cipher = registry[type(cipher), type(mode)](
-            self._backend, cipher, mode
-        )
-        assert evp_cipher != self._backend.ffi.NULL
+        try:
+            adapter = registry[type(cipher), type(mode)]
+        except KeyError:
+            raise UnsupportedAlgorithm
+
+        evp_cipher = adapter(self._backend, cipher, mode)
+        if evp_cipher == self._backend.ffi.NULL:
+            raise UnsupportedAlgorithm
+
         if isinstance(mode, interfaces.ModeWithInitializationVector):
             iv_nonce = mode.initialization_vector
         elif isinstance(mode, interfaces.ModeWithNonce):
@@ -297,19 +319,20 @@ class HMACs(object):
         evp_md = self._backend.lib.EVP_get_digestbyname(
             hash_cls.name.encode('ascii'))
         assert evp_md != self._backend.ffi.NULL
-        res = self._backend.lib.HMAC_Init_ex(ctx, key, len(key), evp_md,
-                                             self._backend.ffi.NULL)
+        res = self._backend.lib.Cryptography_HMAC_Init_ex(
+            ctx, key, len(key), evp_md, self._backend.ffi.NULL
+        )
         assert res != 0
         return ctx
 
     def update_ctx(self, ctx, data):
-        res = self._backend.lib.HMAC_Update(ctx, data, len(data))
+        res = self._backend.lib.Cryptography_HMAC_Update(ctx, data, len(data))
         assert res != 0
 
     def finalize_ctx(self, ctx, digest_size):
         buf = self._backend.ffi.new("unsigned char[]", digest_size)
         buflen = self._backend.ffi.new("unsigned int *", digest_size)
-        res = self._backend.lib.HMAC_Final(ctx, buf, buflen)
+        res = self._backend.lib.Cryptography_HMAC_Final(ctx, buf, buflen)
         assert res != 0
         self._backend.lib.HMAC_CTX_cleanup(ctx)
         return self._backend.ffi.buffer(buf)[:digest_size]
@@ -319,7 +342,7 @@ class HMACs(object):
         self._backend.lib.HMAC_CTX_init(copied_ctx)
         copied_ctx = self._backend.ffi.gc(copied_ctx,
                                           self._backend.lib.HMAC_CTX_cleanup)
-        res = self._backend.lib.HMAC_CTX_copy(copied_ctx, ctx)
+        res = self._backend.lib.Cryptography_HMAC_CTX_copy(copied_ctx, ctx)
         assert res != 0
         return copied_ctx
 
diff --git a/cryptography/hazmat/bindings/openssl/bignum.py b/cryptography/hazmat/bindings/openssl/bignum.py
index 72d467c3..fcfadff1 100644
--- a/cryptography/hazmat/bindings/openssl/bignum.py
+++ b/cryptography/hazmat/bindings/openssl/bignum.py
@@ -32,3 +32,6 @@ int BN_hex2bn(BIGNUM **, const char *);
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/bio.py b/cryptography/hazmat/bindings/openssl/bio.py
index 88be788f..c23dd0d8 100644
--- a/cryptography/hazmat/bindings/openssl/bio.py
+++ b/cryptography/hazmat/bindings/openssl/bio.py
@@ -168,3 +168,6 @@ long BIO_set_buffer_read_data(BIO *, void *, long);
 #define BIO_TYPE_BASE64 ...
 #define BIO_TYPE_FILTER ...
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/conf.py b/cryptography/hazmat/bindings/openssl/conf.py
index 85c7a210..4846252c 100644
--- a/cryptography/hazmat/bindings/openssl/conf.py
+++ b/cryptography/hazmat/bindings/openssl/conf.py
@@ -24,3 +24,6 @@ FUNCTIONS = """
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/crypto.py b/cryptography/hazmat/bindings/openssl/crypto.py
index 501fb5a1..773d9b14 100644
--- a/cryptography/hazmat/bindings/openssl/crypto.py
+++ b/cryptography/hazmat/bindings/openssl/crypto.py
@@ -35,3 +35,6 @@ void CRYPTO_malloc_debug_init();
 #define CRYPTO_MEM_CHECK_ENABLE ...
 #define CRYPTO_MEM_CHECK_DISABLE ...
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/dh.py b/cryptography/hazmat/bindings/openssl/dh.py
index ac130054..b8fbf368 100644
--- a/cryptography/hazmat/bindings/openssl/dh.py
+++ b/cryptography/hazmat/bindings/openssl/dh.py
@@ -26,3 +26,6 @@ void DH_free(DH *);
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/dsa.py b/cryptography/hazmat/bindings/openssl/dsa.py
index 2fa67b87..e6c369a6 100644
--- a/cryptography/hazmat/bindings/openssl/dsa.py
+++ b/cryptography/hazmat/bindings/openssl/dsa.py
@@ -28,3 +28,6 @@ void DSA_free(DSA *);
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/engine.py b/cryptography/hazmat/bindings/openssl/engine.py
index b3ec3125..b76befce 100644
--- a/cryptography/hazmat/bindings/openssl/engine.py
+++ b/cryptography/hazmat/bindings/openssl/engine.py
@@ -50,3 +50,6 @@ MACROS = """
 #define ENGINE_METHOD_ALL ...
 #define ENGINE_METHOD_NONE ...
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/err.py b/cryptography/hazmat/bindings/openssl/err.py
index 39ae315c..6a36dee0 100644
--- a/cryptography/hazmat/bindings/openssl/err.py
+++ b/cryptography/hazmat/bindings/openssl/err.py
@@ -57,3 +57,6 @@ int ERR_GET_FUNC(unsigned long);
 int ERR_GET_REASON(unsigned long);
 int ERR_FATAL_ERROR(unsigned long);
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/evp.py b/cryptography/hazmat/bindings/openssl/evp.py
index 4d0fb7fc..da54f89d 100644
--- a/cryptography/hazmat/bindings/openssl/evp.py
+++ b/cryptography/hazmat/bindings/openssl/evp.py
@@ -29,9 +29,9 @@ typedef struct evp_pkey_st {
 } EVP_PKEY;
 static const int EVP_PKEY_RSA;
 static const int EVP_PKEY_DSA;
-static const int EVP_CTRL_GCM_SET_IVLEN;
-static const int EVP_CTRL_GCM_GET_TAG;
-static const int EVP_CTRL_GCM_SET_TAG;
+static const int Cryptography_EVP_CTRL_GCM_SET_IVLEN;
+static const int Cryptography_EVP_CTRL_GCM_GET_TAG;
+static const int Cryptography_EVP_CTRL_GCM_SET_TAG;
 """
 
 FUNCTIONS = """
@@ -95,3 +95,15 @@ int EVP_PKEY_assign_DSA(EVP_PKEY *, DSA *);
 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *);
 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *, int, int, void *);
 """
+
+CUSTOMIZATIONS = """
+#ifdef EVP_CTRL_GCM_SET_TAG
+const int Cryptography_EVP_CTRL_GCM_GET_TAG = EVP_CTRL_GCM_GET_TAG;
+const int Cryptography_EVP_CTRL_GCM_SET_TAG = EVP_CTRL_GCM_SET_TAG;
+const int Cryptography_EVP_CTRL_GCM_SET_IVLEN = EVP_CTRL_GCM_SET_IVLEN;
+#else
+const int Cryptography_EVP_CTRL_GCM_GET_TAG = -1;
+const int Cryptography_EVP_CTRL_GCM_SET_TAG = -1;
+const int Cryptography_EVP_CTRL_GCM_SET_IVLEN = -1;
+#endif
+"""
diff --git a/cryptography/hazmat/bindings/openssl/hmac.py b/cryptography/hazmat/bindings/openssl/hmac.py
index e97ac35e..10e67141 100644
--- a/cryptography/hazmat/bindings/openssl/hmac.py
+++ b/cryptography/hazmat/bindings/openssl/hmac.py
@@ -22,11 +22,69 @@ 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 *);
+
+int Cryptography_HMAC_Init_ex(HMAC_CTX *, const void *, int, const EVP_MD *,
+                              ENGINE *);
+int Cryptography_HMAC_Update(HMAC_CTX *, const unsigned char *, size_t);
+int Cryptography_HMAC_Final(HMAC_CTX *, unsigned char *, unsigned int *);
+int Cryptography_HMAC_CTX_copy(HMAC_CTX *, HMAC_CTX *);
 """
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+int Cryptography_HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int key_len,
+                              const EVP_MD *md, ENGINE *impl) {
+#if OPENSSL_VERSION_NUMBER >= 0x010000000
+    return HMAC_Init_ex(ctx, key, key_len, md, impl);
+#else
+    HMAC_Init_ex(ctx, key, key_len, md, impl);
+    return 1;
+#endif
+}
+
+int Cryptography_HMAC_Update(HMAC_CTX *ctx, const unsigned char *data,
+                             size_t data_len) {
+#if OPENSSL_VERSION_NUMBER >= 0x010000000
+    return HMAC_Update(ctx, data, data_len);
+#else
+    HMAC_Update(ctx, data, data_len);
+    return 1;
+#endif
+}
+
+int Cryptography_HMAC_Final(HMAC_CTX *ctx, unsigned char *digest,
+    unsigned int *digest_len) {
+#if OPENSSL_VERSION_NUMBER >= 0x010000000
+    return HMAC_Final(ctx, digest, digest_len);
+#else
+    HMAC_Final(ctx, digest, digest_len);
+    return 1;
+#endif
+}
+
+int Cryptography_HMAC_CTX_copy(HMAC_CTX *dst_ctx, HMAC_CTX *src_ctx) {
+#if OPENSSL_VERSION_NUMBER >= 0x010000000
+    return HMAC_CTX_copy(dst_ctx, src_ctx);
+#else
+    HMAC_CTX_init(dst_ctx);
+    if (!EVP_MD_CTX_copy_ex(&dst_ctx->i_ctx, &src_ctx->i_ctx)) {
+        goto err;
+    }
+    if (!EVP_MD_CTX_copy_ex(&dst_ctx->o_ctx, &src_ctx->o_ctx)) {
+        goto err;
+    }
+    if (!EVP_MD_CTX_copy_ex(&dst_ctx->md_ctx, &src_ctx->md_ctx)) {
+        goto err;
+    }
+    memcpy(dst_ctx->key, src_ctx->key, HMAC_MAX_MD_CBLOCK);
+    dst_ctx->key_length = src_ctx->key_length;
+    dst_ctx->md = src_ctx->md;
+    return 1;
+
+    err:
+        return 0;
+#endif
+}
+"""
diff --git a/cryptography/hazmat/bindings/openssl/nid.py b/cryptography/hazmat/bindings/openssl/nid.py
index 0f5b0003..9816dde4 100644
--- a/cryptography/hazmat/bindings/openssl/nid.py
+++ b/cryptography/hazmat/bindings/openssl/nid.py
@@ -39,6 +39,11 @@ static const int NID_crl_reason;
 static const int NID_pbe_WithSHA1And3_Key_TripleDES_CBC;
 """
 
-FUNCTIONS = ""
+FUNCTIONS = """
+"""
+
+MACROS = """
+"""
 
-MACROS = ""
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/opensslv.py b/cryptography/hazmat/bindings/openssl/opensslv.py
index d1a1b3e6..d463776c 100644
--- a/cryptography/hazmat/bindings/openssl/opensslv.py
+++ b/cryptography/hazmat/bindings/openssl/opensslv.py
@@ -24,3 +24,6 @@ FUNCTIONS = """
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/pem.py b/cryptography/hazmat/bindings/openssl/pem.py
index 8c8f736d..00f0dc36 100644
--- a/cryptography/hazmat/bindings/openssl/pem.py
+++ b/cryptography/hazmat/bindings/openssl/pem.py
@@ -41,4 +41,8 @@ PKCS7 *PEM_read_bio_PKCS7(BIO *, PKCS7 **, pem_password_cb *, void *);
 DH *PEM_read_bio_DHparams(BIO *, DH **, pem_password_cb *, void *);
 """
 
-MACROS = ""
+MACROS = """
+"""
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/pkcs12.py b/cryptography/hazmat/bindings/openssl/pkcs12.py
index 5c002b93..d91d100f 100644
--- a/cryptography/hazmat/bindings/openssl/pkcs12.py
+++ b/cryptography/hazmat/bindings/openssl/pkcs12.py
@@ -32,3 +32,6 @@ int PKCS12_parse(PKCS12 *, const char *, EVP_PKEY **, X509 **,
 PKCS12 *PKCS12_create(char *, char *, EVP_PKEY *, X509 *,
                       struct stack_st_X509 *, int, int, int, int, int);
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/pkcs7.py b/cryptography/hazmat/bindings/openssl/pkcs7.py
index 752bfa00..60ea3c52 100644
--- a/cryptography/hazmat/bindings/openssl/pkcs7.py
+++ b/cryptography/hazmat/bindings/openssl/pkcs7.py
@@ -32,3 +32,6 @@ int PKCS7_type_is_enveloped(PKCS7 *);
 int PKCS7_type_is_signedAndEnveloped(PKCS7 *);
 int PKCS7_type_is_data(PKCS7 *);
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/rand.py b/cryptography/hazmat/bindings/openssl/rand.py
index e4f6be23..848ee05a 100644
--- a/cryptography/hazmat/bindings/openssl/rand.py
+++ b/cryptography/hazmat/bindings/openssl/rand.py
@@ -35,3 +35,6 @@ int RAND_pseudo_bytes(unsigned char *, int);
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/rsa.py b/cryptography/hazmat/bindings/openssl/rsa.py
index c8bf1cc0..21ed5d67 100644
--- a/cryptography/hazmat/bindings/openssl/rsa.py
+++ b/cryptography/hazmat/bindings/openssl/rsa.py
@@ -29,3 +29,6 @@ int RSA_check_key(const RSA *);
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/ssl.py b/cryptography/hazmat/bindings/openssl/ssl.py
index 8aca86e4..58a64f0b 100644
--- a/cryptography/hazmat/bindings/openssl/ssl.py
+++ b/cryptography/hazmat/bindings/openssl/ssl.py
@@ -24,3 +24,6 @@ void SSL_load_error_strings();
 
 MACROS = """
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/x509.py b/cryptography/hazmat/bindings/openssl/x509.py
index 9a51a6d0..b2ee672e 100644
--- a/cryptography/hazmat/bindings/openssl/x509.py
+++ b/cryptography/hazmat/bindings/openssl/x509.py
@@ -185,3 +185,6 @@ X509_REVOKED *sk_X509_REVOKED_value(struct x509_revoked_st *, int);
 int X509_CRL_set_lastUpdate(X509_CRL *, const ASN1_TIME *);
 int X509_CRL_set_nextUpdate(X509_CRL *, const ASN1_TIME *);
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/x509name.py b/cryptography/hazmat/bindings/openssl/x509name.py
index bd7abe2d..896f0ae4 100644
--- a/cryptography/hazmat/bindings/openssl/x509name.py
+++ b/cryptography/hazmat/bindings/openssl/x509name.py
@@ -46,3 +46,6 @@ int sk_X509_NAME_push(struct stack_st_X509_NAME *, X509_NAME *);
 X509_NAME *sk_X509_NAME_value(struct stack_st_X509_NAME *, int);
 void sk_X509_NAME_free(struct stack_st_X509_NAME *);
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/bindings/openssl/x509v3.py b/cryptography/hazmat/bindings/openssl/x509v3.py
index 413bde5f..bc26236c 100644
--- a/cryptography/hazmat/bindings/openssl/x509v3.py
+++ b/cryptography/hazmat/bindings/openssl/x509v3.py
@@ -92,3 +92,6 @@ GENERAL_NAME *sk_GENERAL_NAME_value(struct stack_st_GENERAL_NAME *, int);
 const X509V3_EXT_METHOD *X509V3_EXT_get(X509_EXTENSION *);
 const X509V3_EXT_METHOD *X509V3_EXT_get_nid(int);
 """
+
+CUSTOMIZATIONS = """
+"""
diff --git a/cryptography/hazmat/primitives/block/__init__.py b/cryptography/hazmat/primitives/ciphers/__init__.py
index 5b8942b6..e5a8ca52 100644
--- a/cryptography/hazmat/primitives/block/__init__.py
+++ b/cryptography/hazmat/primitives/ciphers/__init__.py
@@ -13,9 +13,9 @@
 
 from __future__ import absolute_import, division, print_function
 
-from cryptography.hazmat.primitives.block.base import BlockCipher
+from cryptography.hazmat.primitives.ciphers.base import Cipher
 
 
 __all__ = [
-    "BlockCipher",
+    "Cipher",
 ]
diff --git a/cryptography/hazmat/primitives/block/ciphers.py b/cryptography/hazmat/primitives/ciphers/algorithms.py
index 8046bd26..8046bd26 100644
--- a/cryptography/hazmat/primitives/block/ciphers.py
+++ b/cryptography/hazmat/primitives/ciphers/algorithms.py
diff --git a/cryptography/hazmat/primitives/block/base.py b/cryptography/hazmat/primitives/ciphers/base.py
index ece3b32d..1599308c 100644
--- a/cryptography/hazmat/primitives/block/base.py
+++ b/cryptography/hazmat/primitives/ciphers/base.py
@@ -16,26 +16,28 @@ from __future__ import absolute_import, division, print_function
 from cryptography.hazmat.primitives import interfaces
 
 
-class BlockCipher(object):
-    def __init__(self, cipher, mode, backend=None):
-        super(BlockCipher, self).__init__()
+class Cipher(object):
+    def __init__(self, algorithm, mode, backend=None):
+        super(Cipher, self).__init__()
 
         if backend is None:
             from cryptography.hazmat.bindings import (
                 _default_backend as backend,
             )
 
-        self.cipher = cipher
+        self.algorithm = algorithm
         self.mode = mode
         self._backend = backend
 
     def encryptor(self):
         return _CipherContext(
-            self._backend.ciphers.create_encrypt_ctx(self.cipher, self.mode))
+            self._backend.ciphers.create_encrypt_ctx(self.algorithm,
+                                                     self.mode))
 
     def decryptor(self):
         return _CipherContext(
-            self._backend.ciphers.create_decrypt_ctx(self.cipher, self.mode))
+            self._backend.ciphers.create_decrypt_ctx(self.algorithm,
+                                                     self.mode))
 
 
 @interfaces.register(interfaces.CipherContext)
diff --git a/cryptography/hazmat/primitives/block/modes.py b/cryptography/hazmat/primitives/ciphers/modes.py
index a60e8a34..e54872a6 100644
--- a/cryptography/hazmat/primitives/block/modes.py
+++ b/cryptography/hazmat/primitives/ciphers/modes.py
@@ -16,6 +16,7 @@ from __future__ import absolute_import, division, print_function
 from cryptography.hazmat.primitives import interfaces
 
 
+@interfaces.register(interfaces.Mode)
 @interfaces.register(interfaces.ModeWithInitializationVector)
 class CBC(object):
     name = "CBC"
@@ -25,10 +26,12 @@ class CBC(object):
         self.initialization_vector = initialization_vector
 
 
+@interfaces.register(interfaces.Mode)
 class ECB(object):
     name = "ECB"
 
 
+@interfaces.register(interfaces.Mode)
 @interfaces.register(interfaces.ModeWithInitializationVector)
 class OFB(object):
     name = "OFB"
@@ -38,6 +41,7 @@ class OFB(object):
         self.initialization_vector = initialization_vector
 
 
+@interfaces.register(interfaces.Mode)
 @interfaces.register(interfaces.ModeWithInitializationVector)
 class CFB(object):
     name = "CFB"
@@ -47,6 +51,7 @@ class CFB(object):
         self.initialization_vector = initialization_vector
 
 
+@interfaces.register(interfaces.Mode)
 @interfaces.register(interfaces.ModeWithNonce)
 class CTR(object):
     name = "CTR"
diff --git a/cryptography/hazmat/primitives/interfaces.py b/cryptography/hazmat/primitives/interfaces.py
index ebf5e31e..67dbe6fa 100644
--- a/cryptography/hazmat/primitives/interfaces.py
+++ b/cryptography/hazmat/primitives/interfaces.py
@@ -25,12 +25,28 @@ def register(iface):
     return register_decorator
 
 
+class Mode(six.with_metaclass(abc.ABCMeta)):
+    @abc.abstractproperty
+    def name(self):
+        """
+        A string naming this mode.  (e.g. ECB, CBC)
+        """
+
+
 class ModeWithInitializationVector(six.with_metaclass(abc.ABCMeta)):
-    pass
+    @abc.abstractproperty
+    def initialization_vector(self):
+        """
+        The value of the initialization vector for this mode as bytes.
+        """
 
 
 class ModeWithNonce(six.with_metaclass(abc.ABCMeta)):
-    pass
+    @abc.abstractproperty
+    def nonce(self):
+        """
+        The value of the nonce for this mode as bytes.
+        """
 
 
 class CipherContext(six.with_metaclass(abc.ABCMeta)):
@@ -65,7 +81,7 @@ class HashAlgorithm(six.with_metaclass(abc.ABCMeta)):
     @abc.abstractproperty
     def name(self):
         """
-        A string naming this algorithm. (ex. sha256, md5)
+        A string naming this algorithm. (e.g. sha256, md5)
         """
 
     @abc.abstractproperty