diff --git a/src/common/dh.py b/src/common/dh.py
index e9b30d32ea6c037e1f783d315dc7ebe696f63b0f..4b038ea939de764641591eb4fa6e23558e4a5350 100644
--- a/src/common/dh.py
+++ b/src/common/dh.py
@@ -19,12 +19,13 @@
## along with Gajim. If not, see <http://www.gnu.org/licenses/>.
##
-import string
+'''
+This module defines a number of constants; specifically, large primes suitable
+for use with the Diffie-Hellman key exchange.
-# This file defines a number of constants; specifically, large primes suitable for
-# use with the Diffie-Hellman key exchange.
-#
-# These constants have been obtained from RFC2409 and RFC3526.
+These constants have been obtained from RFC2409 and RFC3526.
+'''
+import string
generators = [ None, # one to get the right offset
2,
diff --git a/src/common/stanza_session.py b/src/common/stanza_session.py
index d0b0f57fc4e205e84eb42f89bdbe686b7d5cc699..c048b4e07e4b4a664eaeceb1e6391156784e1967 100644
--- a/src/common/stanza_session.py
+++ b/src/common/stanza_session.py
@@ -2,7 +2,6 @@
## src/common/stanza_session.py
##
## Copyright (C) 2007 Julien Pivotto <roidelapluie AT gmail.com>
-## Stephan Erb <steve-e AT h3c.de>
## Copyright (C) 2007-2008 Yann Leboulanger <asterix AT lagaule.org>
## Brendan Taylor <whateley AT gmail.com>
## Jean-Marie Traissard <jim AT lapin.org>
@@ -24,29 +23,36 @@
##
from common import gajim
-
from common import xmpp
-from common import exceptions
+from common.exceptions import DecryptionError, NegotiationError
+import xmpp.c14n
import itertools
import random
import string
-
import time
-
-import xmpp.c14n
-
import base64
import os
+if gajim.HAVE_PYCRYPTO:
+ from Crypto.Cipher import AES
+ from Crypto.Hash import HMAC, SHA256
+ from Crypto.PublicKey import RSA
+ from common import crypto
+
+ from common import dh
+ import secrets
+
XmlDsig = 'http://www.w3.org/2000/09/xmldsig#'
class StanzaSession(object):
+ '''
+ '''
def __init__(self, conn, jid, thread_id, type_):
+ '''
+ '''
self.conn = conn
-
self.jid = jid
-
self.type = type_
if thread_id:
@@ -69,9 +75,11 @@ class StanzaSession(object):
def is_loggable(self):
return self.loggable and gajim.config.should_log(self.conn.name, self.jid)
- # remove events associated with this session from the queue
- # returns True if any events were removed (unlike gajim.events.remove_events)
def remove_events(self, types):
+ '''
+ Remove events associated with this session from the queue.
+ returns True if any events were removed (unlike events.py remove_events)
+ '''
any_removed = False
for j in (self.jid, self.jid.getStripped()):
@@ -124,9 +132,10 @@ class StanzaSession(object):
self.cancelled_negotiation()
def cancelled_negotiation(self):
- '''A negotiation has been cancelled, so reset this session to its default
- state.'''
-
+ '''
+ A negotiation has been cancelled, so reset this session to its default
+ state.
+ '''
if self.control:
self.control.on_cancel_session_negotiation()
@@ -156,61 +165,52 @@ class StanzaSession(object):
# we could send an acknowledgement message to the remote client here
self.status = None
-if gajim.HAVE_PYCRYPTO:
- from Crypto.Cipher import AES
- from Crypto.Hash import HMAC, SHA256
- from Crypto.PublicKey import RSA
- from common import crypto
-
- from common import dh
- import secrets
-
-# an encrypted stanza negotiation has several states. i've represented them
-# as the following values in the 'status'
-# attribute of the session object:
-
-# 1. None:
-# default state
-# 2. 'requested-e2e':
-# this client has initiated an esession negotiation and is waiting
-# for a response
-# 3. 'responded-e2e':
-# this client has responded to an esession negotiation request and
-# is waiting for the initiator to identify itself and complete the
-# negotiation
-# 4. 'identified-alice':
-# this client identified itself and is waiting for the responder to
-# identify itself and complete the negotiation
-# 5. 'active':
-# an encrypted session has been successfully negotiated. messages
-# of any of the types listed in 'encryptable_stanzas' should be
-# encrypted before they're sent.
-
-# the transition between these states is handled in gajim.py's
-# handle_session_negotiation method.
class EncryptedStanzaSession(StanzaSession):
+ '''
+ An encrypted stanza negotiation has several states. They arerepresented as
+ the following values in the 'status' attribute of the session object:
+
+ 1. None:
+ default state
+ 2. 'requested-e2e':
+ this client has initiated an esession negotiation and is waiting
+ for a response
+ 3. 'responded-e2e':
+ this client has responded to an esession negotiation request and
+ is waiting for the initiator to identify itself and complete the
+ negotiation
+ 4. 'identified-alice':
+ this client identified itself and is waiting for the responder to
+ identify itself and complete the negotiation
+ 5. 'active':
+ an encrypted session has been successfully negotiated. messages
+ of any of the types listed in 'encryptable_stanzas' should be
+ encrypted before they're sent.
+
+ The transition between these states is handled in gajim.py's
+ handle_session_negotiation method.
+ '''
def __init__(self, conn, jid, thread_id, type_='chat'):
StanzaSession.__init__(self, conn, jid, thread_id, type_='chat')
self.xes = {}
self.es = {}
-
self.n = 128
-
self.enable_encryption = False
# _s denotes 'self' (ie. this client)
self._kc_s = None
-
# _o denotes 'other' (ie. the client at the other end of the session)
self._kc_o = None
# has the remote contact's identity ever been verified?
self.verified_identity = False
- # keep the encrypter updated with my latest cipher key
def set_kc_s(self, value):
+ '''
+ keep the encrypter updated with my latest cipher key
+ '''
self._kc_s = value
self.encrypter = self.cipher.new(self._kc_s, self.cipher.MODE_CTR,
counter=self.encryptcounter)
@@ -218,8 +218,10 @@ class EncryptedStanzaSession(StanzaSession):
def get_kc_s(self):
return self._kc_s
- # keep the decrypter updated with the other party's latest cipher key
def set_kc_o(self, value):
+ '''
+ keep the decrypter updated with the other party's latest cipher key
+ '''
self._kc_o = value
self.decrypter = self.cipher.new(self._kc_o, self.cipher.MODE_CTR,
counter=self.decryptcounter)
@@ -244,10 +246,10 @@ class EncryptedStanzaSession(StanzaSession):
return crypto.encode_mpi(gajim.pubkey.sign(hash_, '')[0])
def encrypt_stanza(self, stanza):
- encryptable = [x for x in stanza.getChildren() if x.getName() not in ('error', 'amp',
- 'thread')]
+ encryptable = [x for x in stanza.getChildren() if x.getName() not in
+ ('error', 'amp', 'thread')]
- # XXX can also encrypt contents of <error/> elements in stanzas @type =
+ # FIXME can also encrypt contents of <error/> elements in stanzas @type =
# 'error'
# (except for <defined-condition
# xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/> child elements)
@@ -266,7 +268,7 @@ class EncryptedStanzaSession(StanzaSession):
c.setNamespace('http://www.xmpp.org/extensions/xep-0200.html#ns')
c.NT.data = base64.b64encode(m_final)
- # XXX check for rekey request, handle <key/> elements
+ # FIXME check for rekey request, handle <key/> elements
m_content = ''.join(map(str, c.getChildren()))
c.NT.mac = base64.b64encode(self.hmac(self.km_s, m_content + \
@@ -313,7 +315,7 @@ class EncryptedStanzaSession(StanzaSession):
return self.encrypter.encrypt(padded)
def decrypt_stanza(self, stanza):
- # delete the unencrypted explanation body, if it exists
+ ''' delete the unencrypted explanation body, if it exists '''
orig_body = stanza.getTag('body')
if orig_body:
stanza.delChild(orig_body)
@@ -331,7 +333,7 @@ class EncryptedStanzaSession(StanzaSession):
crypto.encode_mpi_with_padding(self.c_o))
if not calculated_mac == received_mac:
- raise exceptions.DecryptionError, 'bad signature'
+ raise DecryptionError('bad signature')
m_final = base64.b64decode(c.getTagData('data'))
m_compressed = self.decrypt(m_final)
@@ -340,7 +342,7 @@ class EncryptedStanzaSession(StanzaSession):
try:
parsed = xmpp.Node(node='<node>' + plaintext + '</node>')
except Exception:
- raise exceptions.DecryptionError, 'decrypted <data/> not parseable as XML'
+ raise DecryptionError('decrypted <data/> not parseable as XML')
for child in parsed.getChildren():
stanza.addChild(node=child)
@@ -358,7 +360,7 @@ class EncryptedStanzaSession(StanzaSession):
def get_shared_secret(self, e, y, p):
if (not 1 < e < (p - 1)):
- raise exceptions.NegotiationError, 'invalid DH value'
+ raise NegotiationError('invalid DH value')
return crypto.sha256(crypto.encode_mpi(crypto.powmod(e, y, p)))
@@ -374,7 +376,8 @@ class EncryptedStanzaSession(StanzaSession):
m_o_calculated = self.hmac(self.km_o, crypto.encode_mpi(self.c_o) + id_o)
if m_o_calculated != m_o:
- raise exceptions.NegotiationError, 'calculated m_%s differs from received m_%s' % (i_o, i_o)
+ raise NegotiationError('calculated m_%s differs from received m_%s' %
+ (i_o, i_o))
if i_o == 'a' and self.sas_algs == 'sas28x5':
# we don't need to calculate this if there's a verified retained secret
@@ -387,7 +390,7 @@ class EncryptedStanzaSession(StanzaSession):
if self.negotiated['recv_pubkey'] == 'hash':
# fingerprint = parsed.getTagData('fingerprint')
- # XXX find stored pubkey or terminate session
+ # FIXME find stored pubkey or terminate session
raise NotImplementedError()
else:
if self.negotiated['sign_algs'] == (XmlDsig + 'rsa-sha256'):
@@ -399,7 +402,7 @@ class EncryptedStanzaSession(StanzaSession):
pubkey_o = xmpp.c14n.c14n(keyvalue)
else:
- # XXX DSA, etc.
+ # FIXME DSA, etc.
raise NotImplementedError()
enc_sig = parsed.getTag(name='SignatureValue',
@@ -426,10 +429,11 @@ class EncryptedStanzaSession(StanzaSession):
hash_ = crypto.sha256(mac_o_calculated)
if not eir_pubkey.verify(hash_, signature):
- raise exceptions.NegotiationError, 'public key signature verification failed!'
+ raise NegotiationError('public key signature verification failed!')
elif mac_o_calculated != mac_o:
- raise exceptions.NegotiationError, 'calculated mac_%s differs from received mac_%s' % (i_o, i_o)
+ raise NegotiationError('calculated mac_%s differs from received mac_%s'
+ % (i_o, i_o))
def make_identity(self, form, dh_i):
if self.negotiated['send_pubkey']:
@@ -476,7 +480,7 @@ class EncryptedStanzaSession(StanzaSession):
self.sas = crypto.sas_28x5(m_s, self.form_o)
if self.sigmai:
- # XXX save retained secret?
+ # FIXME save retained secret?
self.check_identity(tuple)
return (xmpp.DataField(name='identity', value=base64.b64encode(id_s)),
@@ -519,7 +523,7 @@ class EncryptedStanzaSession(StanzaSession):
x.addChild(node=xmpp.DataField(name='init_pubkey', options=['none', 'key',
'hash'], typ='list-single'))
- # XXX store key, use hash
+ # FIXME store key, use hash
x.addChild(node=xmpp.DataField(name='resp_pubkey', options=['none',
'key'], typ='list-single'))
@@ -555,8 +559,8 @@ class EncryptedStanzaSession(StanzaSession):
self.send(request)
- # 4.3 esession response (bob)
def verify_options_bob(self, form):
+ ''' 4.3 esession response (bob) '''
negotiated = {'recv_pubkey': None, 'send_pubkey': None}
not_acceptable = []
ask_user = {}
@@ -618,14 +622,14 @@ class EncryptedStanzaSession(StanzaSession):
if (XmlDsig + 'rsa-sha256') in options:
negotiated['sign_algs'] = XmlDsig + 'rsa-sha256'
else:
- # XXX some things are handled elsewhere, some things are
+ # FIXME some things are handled elsewhere, some things are
# not-implemented
pass
return (negotiated, not_acceptable, ask_user)
- # 4.3 esession response (bob)
def respond_e2e_bob(self, form, negotiated, not_acceptable):
+ ''' 4.3 esession response (bob) '''
response = xmpp.Message()
feature = response.NT.feature
feature.setNamespace(xmpp.NS_FEATURE)
@@ -697,8 +701,8 @@ class EncryptedStanzaSession(StanzaSession):
self.send(response)
- # 'Alice Accepts'
def verify_options_alice(self, form):
+ ''' 'Alice Accepts' '''
negotiated = {}
ask_user = {}
not_acceptable = []
@@ -725,8 +729,8 @@ class EncryptedStanzaSession(StanzaSession):
return (negotiated, not_acceptable, ask_user)
- # 'Alice Accepts', continued
def accept_e2e_alice(self, form, negotiated):
+ ''' 'Alice Accepts', continued '''
self.encryptable_stanzas = ['message']
self.sas_algs = 'sas28x5'
self.cipher = AES
@@ -743,7 +747,6 @@ class EncryptedStanzaSession(StanzaSession):
self.c_s = crypto.decode_mpi(base64.b64decode(form['counter']))
self.c_o = self.c_s ^ (2 ** (self.n - 1))
-
self.n_o = base64.b64decode(form['my_nonce'])
mod_p = int(form['modp'])
@@ -752,7 +755,6 @@ class EncryptedStanzaSession(StanzaSession):
e = self.es[mod_p]
self.d = crypto.decode_mpi(base64.b64decode(form['dhkeys']))
-
self.k = self.get_shared_secret(self.d, x, p)
result.addChild(node=xmpp.DataField(name='FORM_TYPE',
@@ -798,8 +800,8 @@ class EncryptedStanzaSession(StanzaSession):
else:
self.status = 'identified-alice'
- # 4.5 esession accept (bob)
def accept_e2e_bob(self, form):
+ ''' 4.5 esession accept (bob) '''
response = xmpp.Message()
init = response.NT.init
@@ -808,6 +810,7 @@ class EncryptedStanzaSession(StanzaSession):
x = xmpp.DataForm(typ='result')
for field in ('nonce', 'dhkeys', 'rshashes', 'identity', 'mac'):
+ # FIXME: will do nothing in real world...
assert field in form.asDict(), "alice's form didn't have a %s field" \
% field
@@ -816,18 +819,15 @@ class EncryptedStanzaSession(StanzaSession):
p = dh.primes[self.modp]
if crypto.sha256(crypto.encode_mpi(e)) != self.negotiated['He']:
- raise exceptions.NegotiationError, 'SHA256(e) != He'
+ raise NegotiationError('SHA256(e) != He')
k = self.get_shared_secret(e, self.y, p)
-
self.kc_o, self.km_o, self.ks_o = self.generate_initiator_keys(k)
# 4.5.2 verifying alice's identity
-
self.verify_identity(form, e, False, 'a')
# 4.5.4 generating bob's final session keys
-
srs = ''
srses = secrets.secrets().retained_secrets(self.conn.name,
@@ -904,7 +904,6 @@ class EncryptedStanzaSession(StanzaSession):
self.kc_o, self.km_o, self.ks_o = self.generate_responder_keys(k)
# 4.6.2 Verifying Bob's Identity
-
self.verify_identity(form, self.d, False, 'b')
# Note: If Alice discovers an error then she SHOULD ignore any encrypted
# content she received in the stanza.
@@ -919,10 +918,11 @@ class EncryptedStanzaSession(StanzaSession):
self.control.print_esession_details()
def do_retained_secret(self, k, old_srs):
- '''calculate the new retained secret. determine if the user needs to check
- the remote party's identity. set up callbacks for when the identity has
- been verified.'''
-
+ '''
+ Calculate the new retained secret. determine if the user needs to check
+ the remote party's identity. Set up callbacks for when the identity has
+ 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: