python verify the legitimacy of the client

Objective: to connect the server determines the client

# Server 
Import Socket
 Import HMAC
 Import OS 
SECRET_KEY = bytes ( ' Tom ' , encoding = ' UTF-. 8 ' ) 
SK = socket.socket () 
sk.bind (( ' 127.0.0.1 ' , 8010 )) 
sk.listen () 
Connect, addr = sk.accept () 


DEF check_client (Conn):
     "" " 
    use hmac module encrypted 
    new (), if the data type which bytes 
    : param Conn: 
    : return: True or False 
    " "" 
    MSG = OS.    urandom(32)    # Os module may randomly 
    conn.send (MSG) 
    H = hmac.new (SECRET_KEY, MSG) 
    server_digest = h.digest () 
    client_digest = conn.recv (1024 )
     return hmac.compare_digest (server_digest, client_digest) 


RET = check_client ( Connect)
 IF RET:
     Print ( ' the client is a legitimate client ' ) 
    connect.close () 
the else :
     Print ( ' the client is not legitimate client ' ) 
    connect.close () 
sk.close ()

# client
import socket
import hmac
secret_key = bytes('tom', encoding='utf-8')
sk = socket.socket()
sk.connect(('127.0.0.1', 8010))
msg = sk.recv(1024)
h = hmac.new(secret_key, msg)
client_server = h.digest()
sk.send(client_server)
sk.close()