Implementing-cryptography-using-python

216 Chapter 7 ■ Message Integrity
while True:
(data, addr) = UDPSock.recvfrom(buf)
h = hashlib.md5(data)
plaintext = decrypt(data)
msg = str(plaintext, 'utf-8')
print ("Received message: " + msg)
if msg == "exit":
break
if msg == 'newkey':
key = Fernet.generate_key()
f = Fernet(key)
print ("The key is :", str(key, 'utf-8'))
UDPSock.close()
os._exit(0)
The preceding code sample should generate a key for the session, as shown
in Figure 7.5.
Figure 7.5: server.py
The previous implementation will present you with a key. To get both the
client and server communicating with each other, you will need to copy and
paste the provided key to the client window, as shown in Figure 7.5:
# Save as client.py
# Message Sender
import os
from socket import *
from cryptography.fernet import Fernet
host = "127.0.0.1" # set to IP address of target computer
port = 8080
addr = (host, port)
UDPSock = socket(AF_INET, SOCK_DGRAM)