def authenticate_as_client(self, session_socket):
# authenticates an external server connected via session_socket
iv = self.receive_iv(session_socket)
master_encrypter = Encrypter(self.master_key, iv)
m = Messenger(session_socket, master_encrypter, self.continueHandler)
client_challenge = genStr(CHALLENGE_LENGTH)
client_challenge_hash = str(create_key(client_challenge))
hash_len = len(client_challenge_hash)
secretA = generateAorB()
publicA = pow(g, secretA, p)
m.send(client_challenge + str(publicA))
response = m.recv()
while not response:
response = m.recv()
if response[:hash_len] != client_challenge_hash:
m.close()
raise Exception('client could not authenticate')
server_challenge_hash = str(create_key(response[hash_len:hash_len + CHALLENGE_LENGTH]))
m.send(server_challenge_hash)
public_b = int(response[hash_len + CHALLENGE_LENGTH:])
self.log.info('g^b mod p is {}'.format(public_b))
session_key = create_key(str(pow(public_b, secretA, p)))
self.log.info('Session key generated by the client is {}'.format(session_key))
session_encrypter = Encrypter(session_key, iv)
session_m = Messenger(session_socket, session_encrypter, self.continueHandler)
self._messenger = session_m
def authenticate_as_server(self, session_socket):
# authenticates an external client connected via session_socket
iv = self.generate_and_send_iv(session_socket) # the server should generate a random iv
master_encrypter = Encrypter(self.master_key, iv)
m_messenger = Messenger(session_socket, master_encrypter, self.continueHandler)
secret_b = generateAorB()
public_b = str(pow(g, secret_b, p))
server_challenge = genStr(CHALLENGE_LENGTH)
server_challenge_hash = str(create_key(server_challenge))
response = m_messenger.recv()
while not response:
response = m_messenger.recv()
client_challenge = response[:CHALLENGE_LENGTH]
client_challenge_hash = str(create_key(client_challenge))
public_a = response[CHALLENGE_LENGTH:]
self.log.info('publicA is {}'.format(public_a))
m_messenger.send(client_challenge_hash + server_challenge + public_b)
session_key = create_key(str(pow(int(public_a), secret_b, p)))
self.log.info('session key is {}'.format(session_key))
response = m_messenger.recv()
while not response:
response = m_messenger.recv()
if response != server_challenge_hash:
self.log.warn('Client could not be authenticated. Session will be terminated!')
m_messenger.close()
else:
print('Server Authentication Successful!!!')
session_encrypter = Encrypter(session_key, iv)
self._messenger = Messenger(session_socket, session_encrypter, self.continueHandler)