friends/salmoning/__init__.py

   1 #!/usr/bin/python2.4
   2 #
   3 # Copyright 2010 Google Inc. All Rights Reserved.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16 #
  17
  18 """Support library for the Salmon Protocol.
  19
  20 See Salmon I-D for specification.  This module
  21 implements a support library for Salmon on top of the
  22 Magic Envelope library and other bits.
  23 """
  24
  25 __author__ = 'jpanzer@google.com (John Panzer)'
  26
  27
  28 #import base64
  29 #import xml.dom.minidom as dom
  30
  31 import magicsig
  32
  33
  34 class SalmonProtocol(object):
  35   """Implementation of Salmon Protocol."""
  36
  37   magicenv = magicsig.MagicEnvelopeProtocol()
  38
  39   def _GetKeypair(self, signer_uri):
  40     return self.key_retriever.LookupPublicKey(signer_uri)
  41
  42   def SignSalmon(self, text, mimetype, requestor_id):
  43     """Signs a Salmon on behalfo the the current_user.
  44
  45     Input text must be in a recognized format so authorship can be
  46     verified.
  47
  48     Args:
  49       text: Text of message to be signed.
  50       mimetype: The MIME type of the message to sign.
  51       requestor_id: The id of the requestor (usually current logged in user).
  52     Returns:
  53       The Magic Envelope parameters from section 3.1 of the
  54       Magic Signatures spec, as a dict.
  55     """
  56
  57     assert mimetype == 'application/atom+xml'
  58
  59     requestor_id = magicsig.NormalizeUserIdToUri(requestor_id)
  60
  61     if not self.magicenv.IsAllowedSigner(text,
  62         magicsig.NormalizeUserIdToUri(requestor_id)):
  63         # TODO: Fix authorship if missing author, raise
  64         # exception otherwise.
  65         return
  66
  67     env = magicsig.Envelope(
  68         self.magicenv,
  69         raw_data_to_sign=text,
  70         signer_uri=requestor_id,
  71         signer_key=self._GetKeypair(requestor_id),
  72         data_type='application/atom+xml',
  73         encoding='base64url',
  74         alg='RSA-SHA256')
  75
  76
  77     return env.ToXML()
  78
  79   def ParseSalmon(self, text, mimetype):
  80     """Parses a salmon from text with given mimetype.
  81
  82     Returns:
  83       The salmon data as a dict, with fields:
  84     """
  85
  86     self.magicenv.key_retriever = self.key_retriever
  87
  88     return magicsig.Envelope(
  89        self.magicenv,
  90        mime_type=mimetype,
  91        document=text).ToAtom()