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from openid import cryptutil
from openid import oidutil
def strxor(x, y):
if len(x) != len(y):
raise ValueError('Inputs to strxor must have the same length')
xor = lambda (a, b): chr(ord(a) ^ ord(b))
return "".join(map(xor, zip(x, y)))
class DiffieHellman(object):
DEFAULT_MOD = 155172898181473697471232257763715539915724801966915404479707795314057629378541917580651227423698188993727816152646631438561595825688188889951272158842675419950341258706556549803580104870537681476726513255747040765857479291291572334510643245094715007229621094194349783925984760375594985848253359305585439638443L
DEFAULT_GEN = 2
def fromDefaults(cls):
return cls(cls.DEFAULT_MOD, cls.DEFAULT_GEN)
fromDefaults = classmethod(fromDefaults)
def __init__(self, modulus, generator):
self.modulus = long(modulus)
self.generator = long(generator)
self._setPrivate(cryptutil.randrange(1, modulus - 1))
def _setPrivate(self, private):
"""This is here to make testing easier"""
self.private = private
self.public = pow(self.generator, self.private, self.modulus)
def usingDefaultValues(self):
return (self.modulus == self.DEFAULT_MOD and
self.generator == self.DEFAULT_GEN)
def getSharedSecret(self, composite):
return pow(composite, self.private, self.modulus)
def xorSecret(self, composite, secret, hash_func):
dh_shared = self.getSharedSecret(composite)
hashed_dh_shared = hash_func(cryptutil.longToBinary(dh_shared))
return strxor(secret, hashed_dh_shared)