Implementing-cryptography-using-python

Chapter 9 ■ Mastering Cryptography Using Python 251
# no matter what, get the ECC shared key, only use it if the user
enables
clientSecret = get_dh_sharedkey()
print ("Welcome to Crypto-Chat! \n")
print ()
# sending loop
while True:
if sendUsingPrivate == True or sendUsingDH == True:
data = str(input("Enter secure message to send or type
'exit': ")).encode()
else:
data = str(input("Enter message to send or type 'exit': ")).
encode()
# determine if the user initiated a special command
result = ct.check_client_command(data)
# handle any custom commands
if data == b'exit':
break
if result == 0:
break
ciphertext = encrypt(data, sendUsingPrivate, sendUsingDH,
clientSecret)
if skipEncryption:
ciphertext = data;
skipEncryption = False;
# send the packet over UDP
UDPSock.sendto(ciphertext, addr)
# close UDP connection
UDPSock.close()
os._exit(0)
if __name__ == '__main__':
main()
Creating the Helper File
To keep the code as consistent as possible between each step in our design, I
will include various hooks that will be used later but, in this version, will not
be cryptographically functional. The helper file will be the primary focus on
most of our development tasks. Be sure to name this file ch9 _ crypto.py so