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+Submitting Patches
+==================
+
+* Always make a new branch for your work.
+* Patches should be small to facilitate easier review. `Studies have shown`_
+  that review quality falls off as patch size grows. Sometimes this will result
+  in many small PRs to land a single large feature.
+* Larger changes should be discussed on `our mailing list`_ before submission.
+* New features and significant bug fixes should be documented in the
+  :doc:`/changelog`.
+
+If you believe you've identified a security issue in ``cryptography``, please
+follow the directions on the :doc:`security page </security>`.
+
+Code
+----
+
+When in doubt, refer to :pep:`8` for Python code.
+
+`Write comments as complete sentences.`_
+
+Every code file must start with the boilerplate notice of the Apache License.
+Additionally, every Python code file must contain
+
+.. code-block:: python
+
+    from __future__ import absolute_import, division, print_function
+
+API Considerations
+~~~~~~~~~~~~~~~~~~
+
+Most projects' APIs are designed with a philosophy of "make easy things easy,
+and make hard things possible". One of the perils of writing cryptographic code
+is that secure code looks just like insecure code, and its results are almost
+always indistinguishable. As a result ``cryptography`` has, as a design
+philosophy: "make it hard to do insecure things". Here are a few strategies for
+API design that should be both followed, and should inspire other API choices:
+
+If it is necessary to compare a user provided value with a computed value (for
+example, verifying a signature), there should be an API provided that performs
+the verification in a secure way (for example, using a constant time
+comparison), rather than requiring the user to perform the comparison
+themselves.
+
+If it is incorrect to ignore the result of a method, it should raise an
+exception, and not return a boolean ``True``/``False`` flag. For example, a
+method to verify a signature should raise ``InvalidSignature``, and not return
+whether the signature was valid.
+
+.. code-block:: python
+
+    # This is bad.
+    def verify(sig):
+        # ...
+        return is_valid
+
+    # Good!
+    def verify(sig):
+        # ...
+        if not is_valid:
+            raise InvalidSignature
+
+Every recipe should include a version or algorithmic marker of some sort in its
+output in order to allow transparent upgrading of the algorithms in use, as
+the algorithms or parameters needed to achieve a given security margin evolve.
+
+APIs at the :doc:`/hazmat/primitives/index` layer should always take an
+explicit backend, APIs at the recipes layer should automatically use the
+:func:`~cryptography.hazmat.backends.default_backend`, but optionally allow
+specifying a different backend.
+
+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);
+
+...unless they're inside a struct:
+
+.. code-block:: c
+
+    struct my_struct {
+        char *name;
+        int number;
+        ...;
+    };
+
+Include ``void`` if the function takes no arguments:
+
+.. code-block:: c
+
+    // Good
+    long f(void);
+    // Bad
+    long f();
+
+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 *)
+
+Values set by ``#define`` should be assigned the appropriate type. If you see
+this:
+
+.. code-block:: c
+
+    #define SOME_INTEGER_LITERAL 0x0;
+    #define SOME_UNSIGNED_INTEGER_LITERAL 0x0001U;
+    #define SOME_STRING_LITERAL "hello";
+
+...it should be added to the bindings like so:
+
+.. code-block:: c
+
+    static const int SOME_INTEGER_LITERAL;
+    static const unsigned int SOME_UNSIGNED_INTEGER_LITERAL;
+    static const char *const SOME_STRING_LITERAL;
+
+Tests
+-----
+
+All code changes must be accompanied by unit tests with 100% code coverage (as
+measured by the combined metrics across our build matrix).
+
+When implementing a new primitive or recipe ``cryptography`` requires that you
+provide a set of test vectors.
+
+Documentation
+-------------
+
+All features should be documented with prose in the ``docs`` section.
+
+Because of the inherent challenges in implementing correct cryptographic
+systems, we want to make our documentation point people in the right directions
+as much as possible. To that end:
+
+* When documenting a generic interface, use a strong algorithm in examples.
+  (e.g. when showing a hashing example, don't use
+  :class:`~cryptography.hazmat.primitives.hashes.MD5`)
+* When giving prescriptive advice, always provide references and supporting
+  material.
+* When there is real disagreement between cryptographic experts, represent both
+  sides of the argument and describe the trade-offs clearly.
+
+When documenting a new module in the ``hazmat`` package, its documentation
+should begin with the "Hazardous Materials" warning:
+
+.. code-block:: rest
+
+    .. hazmat::
+
+When referring to a hypothetical individual (such as "a person receiving an
+encrypted message") use gender neutral pronouns (they/them/their).
+
+Docstrings are typically only used when writing abstract classes, but should
+be written like this if required:
+
+.. code-block:: python
+
+    def some_function(some_arg):
+        """
+        Does some things.
+
+        :param some_arg: Some argument.
+        """
+
+So, specifically:
+
+* Always use three double quotes.
+* Put the three double quotes on their own line.
+* No blank line at the end.
+* Use Sphinx parameter/attribute documentation `syntax`_.
+
+
+.. _`Write comments as complete sentences.`: http://nedbatchelder.com/blog/201401/comments_should_be_sentences.html
+.. _`syntax`: http://sphinx-doc.org/domains.html#info-field-lists
+.. _`Studies have shown`: http://www.ibm.com/developerworks/rational/library/11-proven-practices-for-peer-review/
+.. _`our mailing list`: https://mail.python.org/mailman/listinfo/cryptography-dev