diff --git a/cryptography/bindings/openssl/evp.py b/cryptography/bindings/openssl/evp.py
index 6336437..ed43c99 100644
--- a/cryptography/bindings/openssl/evp.py
+++ b/cryptography/bindings/openssl/evp.py
@@ -20,6 +20,8 @@
     ...;
 } EVP_CIPHER_CTX;
 typedef ... EVP_CIPHER;
+typedef ... EVP_MD;
+typedef struct env_md_ctx_st EVP_MD_CTX;
 """
 
 FUNCTIONS = """
@@ -35,6 +37,16 @@
 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *);
 int EVP_CIPHER_block_size(const EVP_CIPHER *);
 void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *);
+
+EVP_MD_CTX *EVP_MD_CTX_create();
+int EVP_MD_CTX_copy_ex(EVP_MD_CTX *, const EVP_MD_CTX *);
+int EVP_DigestInit_ex(EVP_MD_CTX *, const EVP_MD *, ENGINE *);
+int EVP_DigestUpdate(EVP_MD_CTX *, const void *, size_t);
+int EVP_DigestFinal_ex(EVP_MD_CTX *, unsigned char *, unsigned int *);
+void EVP_MD_CTX_destroy(EVP_MD_CTX *);
+const EVP_MD *EVP_get_digestbyname(const char *);
+const EVP_MD *EVP_MD_CTX_md(const EVP_MD_CTX *);
+int EVP_MD_size(const EVP_MD *);
 """
 
 MACROS = """
diff --git a/docs/contributing.rst b/docs/contributing.rst
index 2d8fcee..b125d1a 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -20,8 +20,8 @@
 * Patches must *never* be pushed directly to ``master``, all changes (even the
   most trivial typo fixes!) must be submitted as a pull request.
 * A committer may *never* merge their own pull request, a second party must
-  merge their changes. If multiple people work on a pull request, the merger
-  may not be any of them.
+  merge their changes. If multiple people work on a pull request, it must be
+  merged by someone who did not work on it.
 * A patch which breaks tests, or introduces regressions by changing or removing
   existing tests should not be merged. Tests must always be passing on
   ``master``.
@@ -50,6 +50,48 @@
 
     from __future__ import absolute_import, division, print_function
 
+C bindings
+----------
+
+When binding C code with ``cffi`` we have our own style guide, it's pretty
+simple.
+
+Don't name parameters:
+
+.. code-block:: c
+
+    // Good
+    long f(long);
+    // Bad
+    long f(long x);
+
+Don't include stray ``void`` parameters:
+
+.. code-block:: c
+
+    // Good
+    long f();
+    // Bad
+    long f(void);
+
+Wrap lines at 80 characters like so:
+
+.. code-block:: c
+
+    // Pretend this went to 80 characters
+    long f(long, long,
+           int *)
+
+Include a space after commas between parameters:
+
+.. code-block:: c
+
+    // Good
+    long f(int, char *)
+    // Bad
+    long f(int,char *)
+
+
 Documentation
 -------------