A Python helper module to have protected web APIs. This uses a simple secret key, without which the web APIs will restrict users. Thus, only authenticated users possessing the secret key can use the a web API.

This uses HMAC MD5, with a secret key to work.

Quickstart
==========
import web_auth_helper
SECRET = 'My Secret key'

# The encoded message.
s = web_auth_helper.encode(serializable_python_object, SECRET)

# Decode the encoded message.
original_object = web_auth_helper.decode(s, SECRET)


A sample usage is given below (with respect to Django)
======================================================
SECRET = 'This is a sample string used as secret key.'

------------------------------------------------------

from web_auth_helper import encode
import urlib

url = 'http://example.com/api/publish-stream/'
params = { \
    'id': 111, \
    'content': 'This is a sample content.' \
}

signed_request = encode(params, SECRET)

r = urllib.urlopen(url, urllib.urlencode({'signed_request': signed_request}))
r.read()

------------------------------------------------------

from web_auth_helper import decode, DecodeException

@csrf_exempt
def publish_stream_handler(request):
    if request.method == 'POST':
        if not request.POST.has_key('signed_request'):
            return HttpResponseBadRequest('Required parameters not provided.')
        else:
            try:
                request_params = decode(request.POST['signed_request'], SECRET)
            except DecodeException:
                return HttpResponseForbidden('Your request is not allowed.')
            return _do_something_with_params(request_params)
    else:
        return HttpResponseNotAllowed(['POST'])

------------------------------------------------------


Using the 'web_api' decorator in Django views (without any extra modification)
==============================================================================
from django_helper import web_api

@csrf_exempt
@web_api(request_parameter_name='signed_request', secret_key=SECRET)
def publish_stream_handler(request):
    # request.REQUEST and, request.GET or request.POST dictionaries updated
    # to contain the encoded parameters.
    return _do_whatever_required(request)