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authorKali Kaneko (leap communications) <kali@leap.se>2016-08-29 23:00:25 -0400
committerKali Kaneko (leap communications) <kali@leap.se>2016-08-29 23:00:25 -0400
commitaa882b7a64f2c821c8e241a5ff725f27c64fc15f (patch)
tree52554e55956bdd8a5c6596d9b355c36fec00f7cc /src/leap/bitmask/bonafide/_srp.py
parent52abf28677a90780505228dbd6bcba54780766b8 (diff)
[pkg] move bonafide source to leap.bitmask.bonafide
Diffstat (limited to 'src/leap/bitmask/bonafide/_srp.py')
-rw-r--r--src/leap/bitmask/bonafide/_srp.py147
1 files changed, 147 insertions, 0 deletions
diff --git a/src/leap/bitmask/bonafide/_srp.py b/src/leap/bitmask/bonafide/_srp.py
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+++ b/src/leap/bitmask/bonafide/_srp.py
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+# -*- coding: utf-8 -*-
+# _srp.py
+# Copyright (C) 2015 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+"""
+SRP Authentication.
+"""
+
+import binascii
+import json
+
+import srp
+
+
+class SRPAuthMechanism(object):
+
+ """
+ Implement a protocol-agnostic SRP Authentication mechanism.
+ """
+
+ def __init__(self, username, password):
+ self.username = username
+ self.srp_user = srp.User(username, password,
+ srp.SHA256, srp.NG_1024)
+ _, A = self.srp_user.start_authentication()
+ self.A = A
+ self.M = None
+ self.M2 = None
+
+ def get_handshake_params(self):
+ return {'login': bytes(self.username),
+ 'A': binascii.hexlify(self.A)}
+
+ def process_handshake(self, handshake_response):
+ challenge = json.loads(handshake_response)
+ self._check_for_errors(challenge)
+ salt = challenge.get('salt', None)
+ B = challenge.get('B', None)
+ unhex_salt, unhex_B = self._unhex_salt_B(salt, B)
+ self.M = self.srp_user.process_challenge(unhex_salt, unhex_B)
+
+ def get_authentication_params(self):
+ # It looks A is not used server side
+ return {'client_auth': binascii.hexlify(self.M),
+ 'A': binascii.hexlify(self.A)}
+
+ def process_authentication(self, authentication_response):
+ auth = json.loads(authentication_response)
+ self._check_for_errors(auth)
+ uuid = auth.get('id', None)
+ token = auth.get('token', None)
+ self.M2 = auth.get('M2', None)
+ self._check_auth_params(uuid, token, self.M2)
+ return uuid, token
+
+ def verify_authentication(self):
+ unhex_M2 = _safe_unhexlify(self.M2)
+ self.srp_user.verify_session(unhex_M2)
+ assert self.srp_user.authenticated()
+
+ def _check_for_errors(self, response):
+ if 'errors' in response:
+ msg = response['errors']['base']
+ raise SRPAuthError(unicode(msg).encode('utf-8'))
+
+ def _unhex_salt_B(self, salt, B):
+ if salt is None:
+ raise SRPAuthNoSalt()
+ if B is None:
+ raise SRPAuthNoB()
+ try:
+ unhex_salt = _safe_unhexlify(salt)
+ unhex_B = _safe_unhexlify(B)
+ except (TypeError, ValueError) as e:
+ raise SRPAuthBadDataFromServer(str(e))
+ return unhex_salt, unhex_B
+
+ def _check_auth_params(self, uuid, token, M2):
+ if not all((uuid, token, M2)):
+ msg = '%s' % str((M2, uuid, token))
+ raise SRPAuthBadDataFromServer(msg)
+
+
+class SRPSignupMechanism(object):
+
+ """
+ Implement a protocol-agnostic SRP Registration mechanism.
+ """
+
+ def get_signup_params(self, username, password):
+ salt, verifier = srp.create_salted_verification_key(
+ bytes(username), bytes(password),
+ srp.SHA256, srp.NG_1024)
+ user_data = {
+ 'user[login]': username,
+ 'user[password_salt]': binascii.hexlify(salt),
+ 'user[password_verifier]': binascii.hexlify(verifier)}
+ return user_data
+
+ def process_signup(self, signup_response):
+ signup = json.loads(signup_response)
+ errors = signup.get('errors')
+ if errors:
+ msg = 'username ' + errors.get('login')[0]
+ raise SRPRegistrationError(msg)
+ else:
+ username = signup.get('login')
+ return username
+
+
+def _safe_unhexlify(val):
+ return binascii.unhexlify(val) \
+ if (len(val) % 2 == 0) else binascii.unhexlify('0' + val)
+
+
+class SRPAuthError(Exception):
+ """
+ Base exception for srp authentication errors
+ """
+
+
+class SRPAuthNoSalt(SRPAuthError):
+ message = 'The server didn\'t send the salt parameter'
+
+
+class SRPAuthNoB(SRPAuthError):
+ message = 'The server didn\'t send the B parameter'
+
+
+class SRPAuthBadDataFromServer(SRPAuthError):
+ pass
+
+class SRPRegistrationError(Exception):
+ pass