Cosmetic only... as usaual: stanza_session.py. TODO: better variable names
This commit is contained in:
Stephan Erb
parent
d23aa630ba
commit
593c23ebc8
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@ -19,12 +19,13 @@
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## along with Gajim. If not, see <http://www.gnu.org/licenses/>.
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##
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import string
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'''
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This module defines a number of constants; specifically, large primes suitable
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for use with the Diffie-Hellman key exchange.
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# This file defines a number of constants; specifically, large primes suitable for
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# use with the Diffie-Hellman key exchange.
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#
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# These constants have been obtained from RFC2409 and RFC3526.
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These constants have been obtained from RFC2409 and RFC3526.
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'''
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import string
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generators = [ None, # one to get the right offset
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2,
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@ -2,7 +2,6 @@
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## src/common/stanza_session.py
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##
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## Copyright (C) 2007 Julien Pivotto <roidelapluie AT gmail.com>
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## Stephan Erb <steve-e AT h3c.de>
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## Copyright (C) 2007-2008 Yann Leboulanger <asterix AT lagaule.org>
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## Brendan Taylor <whateley AT gmail.com>
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## Jean-Marie Traissard <jim AT lapin.org>
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@ -24,29 +23,36 @@
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##
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from common import gajim
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from common import xmpp
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from common import exceptions
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from common.exceptions import DecryptionError, NegotiationError
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import xmpp.c14n
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import itertools
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import random
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import string
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import time
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import xmpp.c14n
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import base64
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import os
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if gajim.HAVE_PYCRYPTO:
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from Crypto.Cipher import AES
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from Crypto.Hash import HMAC, SHA256
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from Crypto.PublicKey import RSA
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from common import crypto
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from common import dh
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import secrets
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XmlDsig = 'http://www.w3.org/2000/09/xmldsig#'
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class StanzaSession(object):
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'''
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'''
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def __init__(self, conn, jid, thread_id, type_):
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'''
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'''
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self.conn = conn
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self.jid = jid
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self.type = type_
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if thread_id:
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@ -69,9 +75,11 @@ class StanzaSession(object):
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def is_loggable(self):
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return self.loggable and gajim.config.should_log(self.conn.name, self.jid)
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# remove events associated with this session from the queue
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# returns True if any events were removed (unlike gajim.events.remove_events)
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def remove_events(self, types):
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'''
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Remove events associated with this session from the queue.
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returns True if any events were removed (unlike events.py remove_events)
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'''
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any_removed = False
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for j in (self.jid, self.jid.getStripped()):
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@ -124,9 +132,10 @@ class StanzaSession(object):
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self.cancelled_negotiation()
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def cancelled_negotiation(self):
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'''A negotiation has been cancelled, so reset this session to its default
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state.'''
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'''
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A negotiation has been cancelled, so reset this session to its default
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state.
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'''
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if self.control:
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self.control.on_cancel_session_negotiation()
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@ -156,61 +165,52 @@ class StanzaSession(object):
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# we could send an acknowledgement message to the remote client here
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self.status = None
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if gajim.HAVE_PYCRYPTO:
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from Crypto.Cipher import AES
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from Crypto.Hash import HMAC, SHA256
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from Crypto.PublicKey import RSA
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from common import crypto
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from common import dh
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import secrets
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# an encrypted stanza negotiation has several states. i've represented them
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# as the following values in the 'status'
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# attribute of the session object:
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# 1. None:
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# default state
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# 2. 'requested-e2e':
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# this client has initiated an esession negotiation and is waiting
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# for a response
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# 3. 'responded-e2e':
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# this client has responded to an esession negotiation request and
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# is waiting for the initiator to identify itself and complete the
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# negotiation
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# 4. 'identified-alice':
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# this client identified itself and is waiting for the responder to
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# identify itself and complete the negotiation
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# 5. 'active':
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# an encrypted session has been successfully negotiated. messages
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# of any of the types listed in 'encryptable_stanzas' should be
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# encrypted before they're sent.
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# the transition between these states is handled in gajim.py's
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# handle_session_negotiation method.
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class EncryptedStanzaSession(StanzaSession):
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'''
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An encrypted stanza negotiation has several states. They arerepresented as
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the following values in the 'status' attribute of the session object:
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1. None:
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default state
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2. 'requested-e2e':
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this client has initiated an esession negotiation and is waiting
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for a response
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3. 'responded-e2e':
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this client has responded to an esession negotiation request and
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is waiting for the initiator to identify itself and complete the
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negotiation
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4. 'identified-alice':
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this client identified itself and is waiting for the responder to
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identify itself and complete the negotiation
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5. 'active':
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an encrypted session has been successfully negotiated. messages
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of any of the types listed in 'encryptable_stanzas' should be
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encrypted before they're sent.
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The transition between these states is handled in gajim.py's
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handle_session_negotiation method.
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'''
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def __init__(self, conn, jid, thread_id, type_='chat'):
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StanzaSession.__init__(self, conn, jid, thread_id, type_='chat')
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self.xes = {}
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self.es = {}
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self.n = 128
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self.enable_encryption = False
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# _s denotes 'self' (ie. this client)
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self._kc_s = None
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# _o denotes 'other' (ie. the client at the other end of the session)
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self._kc_o = None
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# has the remote contact's identity ever been verified?
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self.verified_identity = False
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# keep the encrypter updated with my latest cipher key
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def set_kc_s(self, value):
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'''
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keep the encrypter updated with my latest cipher key
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'''
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self._kc_s = value
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self.encrypter = self.cipher.new(self._kc_s, self.cipher.MODE_CTR,
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counter=self.encryptcounter)
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@ -218,8 +218,10 @@ class EncryptedStanzaSession(StanzaSession):
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def get_kc_s(self):
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return self._kc_s
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# keep the decrypter updated with the other party's latest cipher key
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def set_kc_o(self, value):
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'''
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keep the decrypter updated with the other party's latest cipher key
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'''
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self._kc_o = value
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self.decrypter = self.cipher.new(self._kc_o, self.cipher.MODE_CTR,
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counter=self.decryptcounter)
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@ -244,10 +246,10 @@ class EncryptedStanzaSession(StanzaSession):
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return crypto.encode_mpi(gajim.pubkey.sign(hash_, '')[0])
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def encrypt_stanza(self, stanza):
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encryptable = [x for x in stanza.getChildren() if x.getName() not in ('error', 'amp',
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'thread')]
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encryptable = [x for x in stanza.getChildren() if x.getName() not in
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('error', 'amp', 'thread')]
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# XXX can also encrypt contents of <error/> elements in stanzas @type =
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# FIXME can also encrypt contents of <error/> elements in stanzas @type =
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# 'error'
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# (except for <defined-condition
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# xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> child elements)
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@ -266,7 +268,7 @@ class EncryptedStanzaSession(StanzaSession):
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c.setNamespace('http://www.xmpp.org/extensions/xep-0200.html#ns')
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c.NT.data = base64.b64encode(m_final)
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# XXX check for rekey request, handle <key/> elements
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# FIXME check for rekey request, handle <key/> elements
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m_content = ''.join(map(str, c.getChildren()))
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c.NT.mac = base64.b64encode(self.hmac(self.km_s, m_content + \
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@ -313,7 +315,7 @@ class EncryptedStanzaSession(StanzaSession):
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return self.encrypter.encrypt(padded)
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def decrypt_stanza(self, stanza):
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# delete the unencrypted explanation body, if it exists
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''' delete the unencrypted explanation body, if it exists '''
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orig_body = stanza.getTag('body')
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if orig_body:
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stanza.delChild(orig_body)
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@ -331,7 +333,7 @@ class EncryptedStanzaSession(StanzaSession):
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crypto.encode_mpi_with_padding(self.c_o))
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if not calculated_mac == received_mac:
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raise exceptions.DecryptionError, 'bad signature'
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raise DecryptionError('bad signature')
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m_final = base64.b64decode(c.getTagData('data'))
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m_compressed = self.decrypt(m_final)
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@ -340,7 +342,7 @@ class EncryptedStanzaSession(StanzaSession):
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try:
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parsed = xmpp.Node(node='<node>' + plaintext + '</node>')
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except Exception:
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raise exceptions.DecryptionError, 'decrypted <data/> not parseable as XML'
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raise DecryptionError('decrypted <data/> not parseable as XML')
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for child in parsed.getChildren():
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stanza.addChild(node=child)
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@ -358,7 +360,7 @@ class EncryptedStanzaSession(StanzaSession):
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def get_shared_secret(self, e, y, p):
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if (not 1 < e < (p - 1)):
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raise exceptions.NegotiationError, 'invalid DH value'
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raise NegotiationError('invalid DH value')
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return crypto.sha256(crypto.encode_mpi(crypto.powmod(e, y, p)))
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@ -374,7 +376,8 @@ class EncryptedStanzaSession(StanzaSession):
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m_o_calculated = self.hmac(self.km_o, crypto.encode_mpi(self.c_o) + id_o)
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if m_o_calculated != m_o:
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raise exceptions.NegotiationError, 'calculated m_%s differs from received m_%s' % (i_o, i_o)
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raise NegotiationError('calculated m_%s differs from received m_%s' %
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(i_o, i_o))
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if i_o == 'a' and self.sas_algs == 'sas28x5':
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# we don't need to calculate this if there's a verified retained secret
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@ -387,7 +390,7 @@ class EncryptedStanzaSession(StanzaSession):
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if self.negotiated['recv_pubkey'] == 'hash':
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# fingerprint = parsed.getTagData('fingerprint')
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# XXX find stored pubkey or terminate session
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# FIXME find stored pubkey or terminate session
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raise NotImplementedError()
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else:
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if self.negotiated['sign_algs'] == (XmlDsig + 'rsa-sha256'):
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@ -399,7 +402,7 @@ class EncryptedStanzaSession(StanzaSession):
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pubkey_o = xmpp.c14n.c14n(keyvalue)
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else:
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# XXX DSA, etc.
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# FIXME DSA, etc.
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raise NotImplementedError()
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enc_sig = parsed.getTag(name='SignatureValue',
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@ -426,10 +429,11 @@ class EncryptedStanzaSession(StanzaSession):
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hash_ = crypto.sha256(mac_o_calculated)
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if not eir_pubkey.verify(hash_, signature):
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raise exceptions.NegotiationError, 'public key signature verification failed!'
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raise NegotiationError('public key signature verification failed!')
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elif mac_o_calculated != mac_o:
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raise exceptions.NegotiationError, 'calculated mac_%s differs from received mac_%s' % (i_o, i_o)
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raise NegotiationError('calculated mac_%s differs from received mac_%s'
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% (i_o, i_o))
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def make_identity(self, form, dh_i):
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if self.negotiated['send_pubkey']:
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@ -476,7 +480,7 @@ class EncryptedStanzaSession(StanzaSession):
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self.sas = crypto.sas_28x5(m_s, self.form_o)
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if self.sigmai:
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# XXX save retained secret?
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# FIXME save retained secret?
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self.check_identity(tuple)
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return (xmpp.DataField(name='identity', value=base64.b64encode(id_s)),
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@ -519,7 +523,7 @@ class EncryptedStanzaSession(StanzaSession):
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x.addChild(node=xmpp.DataField(name='init_pubkey', options=['none', 'key',
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'hash'], typ='list-single'))
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# XXX store key, use hash
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# FIXME store key, use hash
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x.addChild(node=xmpp.DataField(name='resp_pubkey', options=['none',
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'key'], typ='list-single'))
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@ -555,8 +559,8 @@ class EncryptedStanzaSession(StanzaSession):
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self.send(request)
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# 4.3 esession response (bob)
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def verify_options_bob(self, form):
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''' 4.3 esession response (bob) '''
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negotiated = {'recv_pubkey': None, 'send_pubkey': None}
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not_acceptable = []
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ask_user = {}
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@ -618,14 +622,14 @@ class EncryptedStanzaSession(StanzaSession):
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if (XmlDsig + 'rsa-sha256') in options:
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negotiated['sign_algs'] = XmlDsig + 'rsa-sha256'
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else:
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# XXX some things are handled elsewhere, some things are
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# FIXME some things are handled elsewhere, some things are
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# not-implemented
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pass
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return (negotiated, not_acceptable, ask_user)
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# 4.3 esession response (bob)
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def respond_e2e_bob(self, form, negotiated, not_acceptable):
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''' 4.3 esession response (bob) '''
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response = xmpp.Message()
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feature = response.NT.feature
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feature.setNamespace(xmpp.NS_FEATURE)
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@ -697,8 +701,8 @@ class EncryptedStanzaSession(StanzaSession):
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self.send(response)
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# 'Alice Accepts'
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def verify_options_alice(self, form):
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''' 'Alice Accepts' '''
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negotiated = {}
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ask_user = {}
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not_acceptable = []
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@ -725,8 +729,8 @@ class EncryptedStanzaSession(StanzaSession):
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return (negotiated, not_acceptable, ask_user)
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# 'Alice Accepts', continued
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def accept_e2e_alice(self, form, negotiated):
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''' 'Alice Accepts', continued '''
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self.encryptable_stanzas = ['message']
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self.sas_algs = 'sas28x5'
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self.cipher = AES
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@ -743,7 +747,6 @@ class EncryptedStanzaSession(StanzaSession):
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self.c_s = crypto.decode_mpi(base64.b64decode(form['counter']))
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self.c_o = self.c_s ^ (2 ** (self.n - 1))
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self.n_o = base64.b64decode(form['my_nonce'])
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mod_p = int(form['modp'])
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@ -752,7 +755,6 @@ class EncryptedStanzaSession(StanzaSession):
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e = self.es[mod_p]
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self.d = crypto.decode_mpi(base64.b64decode(form['dhkeys']))
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self.k = self.get_shared_secret(self.d, x, p)
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result.addChild(node=xmpp.DataField(name='FORM_TYPE',
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@ -798,8 +800,8 @@ class EncryptedStanzaSession(StanzaSession):
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else:
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self.status = 'identified-alice'
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# 4.5 esession accept (bob)
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def accept_e2e_bob(self, form):
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''' 4.5 esession accept (bob) '''
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response = xmpp.Message()
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init = response.NT.init
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@ -808,6 +810,7 @@ class EncryptedStanzaSession(StanzaSession):
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x = xmpp.DataForm(typ='result')
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for field in ('nonce', 'dhkeys', 'rshashes', 'identity', 'mac'):
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# FIXME: will do nothing in real world...
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assert field in form.asDict(), "alice's form didn't have a %s field" \
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% field
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@ -816,18 +819,15 @@ class EncryptedStanzaSession(StanzaSession):
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p = dh.primes[self.modp]
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if crypto.sha256(crypto.encode_mpi(e)) != self.negotiated['He']:
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raise exceptions.NegotiationError, 'SHA256(e) != He'
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raise NegotiationError('SHA256(e) != He')
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k = self.get_shared_secret(e, self.y, p)
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self.kc_o, self.km_o, self.ks_o = self.generate_initiator_keys(k)
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# 4.5.2 verifying alice's identity
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self.verify_identity(form, e, False, 'a')
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# 4.5.4 generating bob's final session keys
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srs = ''
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srses = secrets.secrets().retained_secrets(self.conn.name,
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@ -904,7 +904,6 @@ class EncryptedStanzaSession(StanzaSession):
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self.kc_o, self.km_o, self.ks_o = self.generate_responder_keys(k)
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# 4.6.2 Verifying Bob's Identity
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self.verify_identity(form, self.d, False, 'b')
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# Note: If Alice discovers an error then she SHOULD ignore any encrypted
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# content she received in the stanza.
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@ -919,10 +918,11 @@ class EncryptedStanzaSession(StanzaSession):
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self.control.print_esession_details()
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def do_retained_secret(self, k, old_srs):
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'''calculate the new retained secret. determine if the user needs to check
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the remote party's identity. set up callbacks for when the identity has
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been verified.'''
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'''
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Calculate the new retained secret. determine if the user needs to check
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the remote party's identity. Set up callbacks for when the identity has
|
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been verified.
|
||||
'''
|
||||
new_srs = self.hmac(k, 'New Retained Secret')
|
||||
self.srs = new_srs
|
||||
|
||||
|
|
@ -962,7 +962,7 @@ class EncryptedStanzaSession(StanzaSession):
|
|||
|
||||
x = crypto.srand(2 ** (2 * self.n - 1), p - 1)
|
||||
|
||||
# XXX this may be a source of performance issues
|
||||
# FIXME this may be a source of performance issues
|
||||
e = crypto.powmod(g, x, p)
|
||||
|
||||
self.xes[modp] = x
|
||||
|
|
@ -980,21 +980,19 @@ class EncryptedStanzaSession(StanzaSession):
|
|||
|
||||
def terminate_e2e(self):
|
||||
self.terminate()
|
||||
|
||||
self.enable_encryption = False
|
||||
|
||||
def acknowledge_termination(self):
|
||||
StanzaSession.acknowledge_termination(self)
|
||||
|
||||
self.enable_encryption = False
|
||||
|
||||
def fail_bad_negotiation(self, reason, fields = None):
|
||||
'''sends an error and cancels everything.
|
||||
|
||||
if fields is None, the remote party has given us a bad cryptographic value of some kind
|
||||
|
||||
otherwise, list the fields we haven't implemented'''
|
||||
|
||||
def fail_bad_negotiation(self, reason, fields=None):
|
||||
'''
|
||||
Sends an error and cancels everything.
|
||||
|
||||
If fields is None, the remote party has given us a bad cryptographic
|
||||
value of some kind. Otherwise, list the fields we haven't implemented
|
||||
'''
|
||||
err = xmpp.Error(xmpp.Message(), xmpp.ERR_FEATURE_NOT_IMPLEMENTED)
|
||||
err.T.error.T.text.setData(reason)
|
||||
|
||||
|
|
@ -1020,7 +1018,6 @@ otherwise, list the fields we haven't implemented'''
|
|||
def cancelled_negotiation(self):
|
||||
StanzaSession.cancelled_negotiation(self)
|
||||
self.enable_encryption = False
|
||||
|
||||
self.km_o = ''
|
||||
|
||||
# vim: se ts=3:
|
||||
|
|
|
|||
Loading…
Reference in New Issue