requests-http-signature: A Requests auth module for HTTP Signature
==================================================================
**requests-http-signature** is a `Requests <https://github.com/requests/requests>`_ `authentication plugin
<http://docs.python-requests.org/en/master/user/authentication/>`_ (``requests.auth.AuthBase`` subclass) implementing
the `IETF HTTP Signatures draft RFC <https://tools.ietf.org/html/draft-cavage-http-signatures>`_. It has no required
dependencies outside the standard library. If you wish to use algorithms other than HMAC (namely, RSA and ECDSA algorithms
specified in the RFC), there is an optional dependency on `cryptography <https://pypi.python.org/pypi/cryptography>`_.

Installation
------------
::

    $ pip install requests-http-signature

Usage
-----

.. code-block:: python

  import requests
  from requests_http_signature import HTTPSignatureAuth
  
  preshared_key_id = 'squirrel'
  preshared_secret = 'monorail_cat'
  url = 'http://example.com/path'
  
  requests.get(url, auth=HTTPSignatureAuth(key=preshared_secret, key_id=preshared_key_id))

By default, only the ``Date`` header is signed (as per the RFC) for body-less requests such as GET. The ``Date`` header
is set if it is absent. In addition, for requests with bodies (such as POST), the ``Digest`` header is set to the SHA256
of the request body and signed (an example of this appears in the RFC). To add other headers to the signature, pass an
array of header names in the ``header`` keyword argument.

In addition to signing messages in the client, the class method ``HTTPSignatureAuth.verify()`` can be used to verify
incoming requests:

.. code-block:: python

  def key_resolver(key_id, algorithm):
      return 'monorail_cat'

  HTTPSignatureAuth.verify(request, key_resolver=key_resolver)

Asymmetric key algorithms (RSA and ECDSA)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For asymmetric key algorithms, you should supply the private key as the ``key`` parameter to the ``HTTPSignatureAuth()`` 
constructor as bytes in the PEM format:

.. code-block:: python

  with open('key.pem', 'rb') as fh:
      requests.get(url, auth=HTTPSignatureAuth(algorithm="rsa-sha256", key=fh.read(), key_id=preshared_key_id))

When verifying, the ``key_resolver()`` callback should provide the public key as bytes in the PEM format as well:

Links
-----
* `IETF HTTP Signatures draft <https://tools.ietf.org/html/draft-cavage-http-signatures>`_
* https://github.com/joyent/node-http-signature
* `Project home page (GitHub) <https://github.com/kislyuk/requests-http-signature>`_
* `Documentation (Read the Docs) <https://requests-http-signature.readthedocs.io/en/latest/>`_
* `Package distribution (PyPI) <https://pypi.python.org/pypi/requests-http-signature>`_
* `Change log <https://github.com/kislyuk/requests-http-signature/blob/master/Changes.rst>`_

Bugs
~~~~
Please report bugs, issues, feature requests, etc. on `GitHub <https://github.com/kislyuk/requests-http-signature/issues>`_.

License
-------
Licensed under the terms of the `Apache License, Version 2.0 <http://www.apache.org/licenses/LICENSE-2.0>`_.

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