Source Code for Module openid.dh

 1  from openid import cryptutil 
 2  from openid import oidutil 
 3   
 4 -def strxor(x, y): 
 5      if len(x) != len(y): 
 6          raise ValueError('Inputs to strxor must have the same length') 
 7   
 8      xor = lambda (a, b): chr(ord(a) ^ ord(b)) 
 9      return "".join(map(xor, zip(x, y))) 
10   
11 -class DiffieHellman(object): 
12      DEFAULT_MOD = 155172898181473697471232257763715539915724801966915404479707795314057629378541917580651227423698188993727816152646631438561595825688188889951272158842675419950341258706556549803580104870537681476726513255747040765857479291291572334510643245094715007229621094194349783925984760375594985848253359305585439638443L 
13   
14      DEFAULT_GEN = 2 
15   
16 -    def fromDefaults(cls): 
17          return cls(cls.DEFAULT_MOD, cls.DEFAULT_GEN) 
18   
19      fromDefaults = classmethod(fromDefaults) 
20   
21 -    def __init__(self, modulus, generator): 
22          self.modulus = long(modulus) 
23          self.generator = long(generator) 
24   
25          self._setPrivate(cryptutil.randrange(1, modulus - 1)) 
26   
27 -    def _setPrivate(self, private): 
28          """This is here to make testing easier""" 
29          self.private = private 
30          self.public = pow(self.generator, self.private, self.modulus) 
31   
32 -    def usingDefaultValues(self): 
33          return (self.modulus == self.DEFAULT_MOD and 
34                  self.generator == self.DEFAULT_GEN) 
35   
36 -    def getSharedSecret(self, composite): 
37          return pow(composite, self.private, self.modulus) 
38   
39 -    def xorSecret(self, composite, secret, hash_func): 
40          dh_shared = self.getSharedSecret(composite) 
41          hashed_dh_shared = hash_func(cryptutil.longToBinary(dh_shared)) 
42          return strxor(secret, hashed_dh_shared) 
43