Add HMAC bindings
diff --git a/cryptography/bindings/openssl/api.py b/cryptography/bindings/openssl/api.py
index f5e042e..12082c0 100644
--- a/cryptography/bindings/openssl/api.py
+++ b/cryptography/bindings/openssl/api.py
@@ -35,6 +35,7 @@
"engine",
"err",
"evp",
+ "hmac",
"nid",
"opensslv",
"pem",
diff --git a/cryptography/bindings/openssl/hmac.py b/cryptography/bindings/openssl/hmac.py
new file mode 100644
index 0000000..7a9d05b
--- /dev/null
+++ b/cryptography/bindings/openssl/hmac.py
@@ -0,0 +1,33 @@
+# 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 = """
+struct hmac_ctx_st { ...; };
+typedef struct hmac_ctx_st 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 = """
+"""