def compute_client_values(self, byte_size=DEFAULT_SECRETSIZE):
'''
Computes client's private and public values:
a = random()
A = g^a % N
'''
self.a = obj_to_int(get_randombytes(byte_size))
self.A = pow(self.g, self.a, self.N)
return self.A
def compute_server_values(self,
username,
verifier,
byte_size=DEFAULT_SECRETSIZE):
'''Calculates server values'''
l = self.N.bit_length()
self.b = obj_to_int(get_randombytes(byte_size))
k = obj_to_int(compute_hash(self.N, compute_padding(self.g, l)))
self.B = (k * verifier + pow(self.g, self.b, self.N)) % self.N
return self.B
def compute_verifier(self,
username,
password,
gn=DEFAULT_GROUP_PARAMETERS,
byte_size=DEFAULT_SALT_SIZE):
'''Creates the SRP verifier according to the RFC formula'''
self.username = username
self.password = password
salt = get_randombytes(byte_size)
x = self._compute_x(salt, username, password)
verifier = pow(self.g, x, self.N)
return salt, verifier