def gen_A(self):
"""Generate A as defined in SRP6: A= ModPow(g, a, N)
A is the Public ephemeral value (client generated)
"""
A = pow(self.g.ibig(), self.a.ibig(), self.N.ibig()) # A is Big Endian
self.A = Endian(self.int_to_bytes(A)[::-1]) # self.A is converted to Endian(little_end)
return self.A
def gen_u(self):
"""Calculate the random scrambling parameter u = H(A,B)"""
hash_object = hashlib.sha1()
try:
hash_object.update(self.A.blittle())
except AttributeError:
raise ValueError("You need to generate A first.\nYou can do this calling gen_A()")
hash_object.update(self.B.blittle())
hashed = hash_object.digest()
self.u = Endian(hashed)
return self.u
def gen_M(self):
"""Generate M (client side)"""
hN = hashlib.sha1(self.N.blittle()).digest()
hg = hashlib.sha1(self.g.blittle()).digest()
hN_xor_hg = ''.join(chr(ord(hN[i]) ^ ord(hg[i])) for i in range(0, len(hN)))
try:
hash_object = hashlib.sha1(hN_xor_hg)
hash_object.update(hashlib.sha1(self.I).digest())
hash_object.update(self.s.b_little)
hash_object.update(self.A.b_little)
hash_object.update(self.B.b_little)
hash_object.update(self.K.b_little)
except AttributeError:
raise ValueError("You need to call gen_K() first!")
self.M = Endian(hash_object.digest())
return self.M
def gen_K(self):
"""Generate K by S with SHA1 Interleaved"""
try:
s_bytes = self.S.blittle()
except AttributeError:
raise ValueError("You need to generate S first.\nYou can do this calling gen_S()")
# Hash the even bytes of S (session key)
hash_object = hashlib.sha1(s_bytes[::2])
even_hashed = hash_object.digest()
# Hash the odd bytes of S
hash_object = hashlib.sha1(s_bytes[1::2])
odd_hashed = hash_object.digest()
K = ""
# Create K as alternate string concatenation
for o, e in zip(even_hashed, odd_hashed):
K += o + e # K = odd[0],even[0],odd[1],..
self.K = Endian(K)
return self.K
def gen_S(self):
"""Calculate client session key
x = H(s, H(I:P))
"""
hash_object = hashlib.sha1(self.I + ':' + self.p)
ih = hash_object.digest() # WoW requires to gen x with I=H(user:pass))
hash_object = hashlib.sha1(self.s.blittle())
hash_object.update(ih)
x = Endian(hash_object.digest())
v = pow(self.g.ibig(), x.ibig(), self.N.ibig()) # Note: v is an int big-Endian
try:
S = pow(self.B.ibig() - self.k.ibig() * v, # v is already int big-Endian
self.a.ibig() + self.u.ibig() * x.ibig(),
self.N.ibig()) # Note: S is an int big-Endian
except AttributeError:
raise ValueError("You need to generate u first.\nYou can do this calling gen_u()")
self.S = Endian(self.int_to_bytes(S)[::-1])
return self.S
def __init__(self, N, g, I, p, s, B, k=3):
"""Initialize the class
"""
# N,g,s,B should be in bytestring format ("\x01\x10\x03")
self.a = Endian(os.urandom(32)) # Used to calculate A
self.N = Endian(N) # N is a safe prime, sended by server (all op. are mod N)
self.g = Endian(g) # g is a generator of the multiplicative group
self.I = I # Username
self.p = p # Password
self.s = Endian(s) # Salt, generated and sent by server
self.B = Endian(B) # Public ephemeral value (server generated)
self.k = Endian(self.int_to_bytes(k)) # Multiplier parameter (k = 3 in SRP6, k = H(N, g) in SRP-6a)
if self.B.ibig() % self.N.ibig() == 0:
raise Exception()
class Srp:
"""A class for using an edited SRP6, created to work with WoW Logon system."""
def __init__(self, N, g, I, p, s, B, k=3):
"""Initialize the class
"""
# N,g,s,B should be in bytestring format ("\x01\x10\x03")
self.a = Endian(os.urandom(32)) # Used to calculate A
self.N = Endian(N) # N is a safe prime, sended by server (all op. are mod N)
self.g = Endian(g) # g is a generator of the multiplicative group
self.I = I # Username
self.p = p # Password
self.s = Endian(s) # Salt, generated and sent by server
self.B = Endian(B) # Public ephemeral value (server generated)
self.k = Endian(self.int_to_bytes(k)) # Multiplier parameter (k = 3 in SRP6, k = H(N, g) in SRP-6a)
if self.B.ibig() % self.N.ibig() == 0:
raise Exception()
def gen_A(self):
"""Generate A as defined in SRP6: A= ModPow(g, a, N)
A is the Public ephemeral value (client generated)
"""
A = pow(self.g.ibig(), self.a.ibig(), self.N.ibig()) # A is Big Endian
self.A = Endian(self.int_to_bytes(A)[::-1]) # self.A is converted to Endian(little_end)
return self.A
def gen_u(self):
"""Calculate the random scrambling parameter u = H(A,B)"""
hash_object = hashlib.sha1()
try:
hash_object.update(self.A.blittle())
except AttributeError:
raise ValueError("You need to generate A first.\nYou can do this calling gen_A()")
hash_object.update(self.B.blittle())
hashed = hash_object.digest()
self.u = Endian(hashed)
return self.u
def gen_S(self):
"""Calculate client session key
x = H(s, H(I:P))
"""
hash_object = hashlib.sha1(self.I + ':' + self.p)
ih = hash_object.digest() # WoW requires to gen x with I=H(user:pass))
hash_object = hashlib.sha1(self.s.blittle())
hash_object.update(ih)
x = Endian(hash_object.digest())
v = pow(self.g.ibig(), x.ibig(), self.N.ibig()) # Note: v is an int big-Endian
try:
S = pow(self.B.ibig() - self.k.ibig() * v, # v is already int big-Endian
self.a.ibig() + self.u.ibig() * x.ibig(),
self.N.ibig()) # Note: S is an int big-Endian
except AttributeError:
raise ValueError("You need to generate u first.\nYou can do this calling gen_u()")
self.S = Endian(self.int_to_bytes(S)[::-1])
return self.S
def gen_K(self):
"""Generate K by S with SHA1 Interleaved"""
try:
s_bytes = self.S.blittle()
except AttributeError:
raise ValueError("You need to generate S first.\nYou can do this calling gen_S()")
# Hash the even bytes of S (session key)
hash_object = hashlib.sha1(s_bytes[::2])
even_hashed = hash_object.digest()
# Hash the odd bytes of S
hash_object = hashlib.sha1(s_bytes[1::2])
odd_hashed = hash_object.digest()
K = ""
# Create K as alternate string concatenation
for o, e in zip(even_hashed, odd_hashed):
K += o + e # K = odd[0],even[0],odd[1],..
self.K = Endian(K)
return self.K
def gen_M(self):
"""Generate M (client side)"""
hN = hashlib.sha1(self.N.blittle()).digest()
hg = hashlib.sha1(self.g.blittle()).digest()
hN_xor_hg = ''.join(chr(ord(hN[i]) ^ ord(hg[i])) for i in range(0, len(hN)))
try:
hash_object = hashlib.sha1(hN_xor_hg)
hash_object.update(hashlib.sha1(self.I).digest())
hash_object.update(self.s.b_little)
hash_object.update(self.A.b_little)
hash_object.update(self.B.b_little)
hash_object.update(self.K.b_little)
except AttributeError:
raise ValueError("You need to call gen_K() first!")
self.M = Endian(hash_object.digest())
return self.M
@staticmethod
def int_to_bytes(n):
l = []
x = 0
off = 0
while x != n:
b = (n >> off) & 0xFF
l.append(chr(b))
x |= b << off
off += 8
l.reverse()
return ''.join(l)