OTR plugin for Gajim 1.0+
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# Copyright 2012 Kjell Braden <afflux@pentabarf.de>
#
# This file is part of the python-potr library.
#
# python-potr is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# any later version.
#
# python-potr 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this library. If not, see <http://www.gnu.org/licenses/>.
try:
import Crypto
except ImportError:
import crypto as Crypto
from Crypto import Cipher
from Crypto.Hash import SHA256 as _SHA256
from Crypto.Hash import SHA as _SHA1
from Crypto.Hash import HMAC as _HMAC
from Crypto.PublicKey import DSA
import Crypto.Random.random
from numbers import Number
from potr.compatcrypto import common
from potr.utils import read_mpi, bytes_to_long, long_to_bytes
def SHA256(data):
return _SHA256.new(data).digest()
def SHA1(data):
return _SHA1.new(data).digest()
def SHA1HMAC(key, data):
return _HMAC.new(key, msg=data, digestmod=_SHA1).digest()
def SHA256HMAC(key, data):
return _HMAC.new(key, msg=data, digestmod=_SHA256).digest()
def AESCTR(key, counter=0):
if isinstance(counter, Number):
counter = Counter(counter)
if not isinstance(counter, Counter):
raise TypeError
return Cipher.AES.new(key, Cipher.AES.MODE_CTR, counter=counter)
class Counter(object):
def __init__(self, prefix):
self.prefix = prefix
self.val = 0
def inc(self):
self.prefix += 1
self.val = 0
def __setattr__(self, attr, val):
if attr == 'prefix':
self.val = 0
super(Counter, self).__setattr__(attr, val)
def __repr__(self):
return '<Counter(p={p!r},v={v!r})>'.format(p=self.prefix, v=self.val)
def byteprefix(self):
return long_to_bytes(self.prefix, 8)
def __call__(self):
bytesuffix = long_to_bytes(self.val, 8)
self.val += 1
return self.byteprefix() + bytesuffix
@common.registerkeytype
class DSAKey(common.PK):
keyType = 0x0000
def __init__(self, key=None, private=False):
self.priv = self.pub = None
if not isinstance(key, tuple):
raise TypeError('4/5-tuple required for key')
if len(key) == 5 and private:
self.priv = DSA.construct(key)
self.pub = self.priv.publickey()
elif len(key) == 4 and not private:
self.pub = DSA.construct(key)
else:
raise TypeError('wrong number of arguments for ' \
'private={0!r}: got {1} '
.format(private, len(key)))
def getPublicPayload(self):
return (self.pub.p, self.pub.q, self.pub.g, self.pub.y)
def getPrivatePayload(self):
return (self.priv.p, self.priv.q, self.priv.g, self.priv.y, self.priv.x)
def fingerprint(self):
return SHA1(self.getSerializedPublicPayload())
def sign(self, data):
# 2 <= K <= q
K = randrange(2, self.priv.q)
r, s = self.priv.sign(data, K)
return long_to_bytes(r, 20) + long_to_bytes(s, 20)
def verify(self, data, sig):
r, s = bytes_to_long(sig[:20]), bytes_to_long(sig[20:])
return self.pub.verify(data, (r, s))
def __hash__(self):
return bytes_to_long(self.fingerprint())
def __eq__(self, other):
if not isinstance(other, type(self)):
return False
return self.fingerprint() == other.fingerprint()
def __ne__(self, other):
return not (self == other)
@classmethod
def generate(cls):
privkey = DSA.generate(1024)
return cls((privkey.key.y, privkey.key.g, privkey.key.p, privkey.key.q,
privkey.key.x), private=True)
@classmethod
def parsePayload(cls, data, private=False):
p, data = read_mpi(data)
q, data = read_mpi(data)
g, data = read_mpi(data)
y, data = read_mpi(data)
if private:
x, data = read_mpi(data)
return cls((y, g, p, q, x), private=True), data
return cls((y, g, p, q), private=False), data
def getrandbits(k):
return Crypto.Random.random.getrandbits(k)
def randrange(start, stop):
return Crypto.Random.random.randrange(start, stop)