48 lines
1.6 KiB
Python
48 lines
1.6 KiB
Python
from openid import cryptutil
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def strxor(x, y):
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if len(x) != len(y):
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raise ValueError('Inputs to strxor must have the same length')
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if isinstance(x, str):
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x = x.encode("utf-8")
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if isinstance(y, str):
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y = y.encode("utf-8")
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return bytes([a ^ b for a, b in zip(x, y)])
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class DiffieHellman(object):
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DEFAULT_MOD = 155172898181473697471232257763715539915724801966915404479707795314057629378541917580651227423698188993727816152646631438561595825688188889951272158842675419950341258706556549803580104870537681476726513255747040765857479291291572334510643245094715007229621094194349783925984760375594985848253359305585439638443
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DEFAULT_GEN = 2
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def fromDefaults(cls):
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return cls(cls.DEFAULT_MOD, cls.DEFAULT_GEN)
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fromDefaults = classmethod(fromDefaults)
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def __init__(self, modulus, generator):
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self.modulus = int(modulus)
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self.generator = int(generator)
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self._setPrivate(cryptutil.randrange(1, modulus - 1))
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def _setPrivate(self, private):
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"""This is here to make testing easier"""
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self.private = private
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self.public = pow(self.generator, self.private, self.modulus)
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def usingDefaultValues(self):
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return (self.modulus == self.DEFAULT_MOD and
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self.generator == self.DEFAULT_GEN)
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def getSharedSecret(self, composite):
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return pow(composite, self.private, self.modulus)
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def xorSecret(self, composite, secret, hash_func):
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dh_shared = self.getSharedSecret(composite)
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hashed_dh_shared = hash_func(cryptutil.longToBinary(dh_shared))
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return strxor(secret, hashed_dh_shared)
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