Implementing-cryptography-using-python

Chapter 9 ■ Mastering Cryptography Using Python 257
The command being used in this example is addPKI:
# send the data packet for decryption
plaintext = decrypt(data, useClientPKI, useDHKey, serverSecret)
# check to see if the user typed a special command such as addPKI or
addDH
result = ct.check_server_command(plaintext)
if result == 10: # encryption has been disabled so no message
plaintext = b'PKI Encryption disabled!'
elif result == 11: # encryption enabled
plaintext = b'PKI Encryption enabled!'
# messages are received encoded so you must decode the message for
processing
msg = str(plaintext, 'utf-8')
# process any client special commands
if result == 0:
# no encryption
break
if result == 10:
# turn off the use of PKI
useClientPKI = False;
if result == 11:
# turn on the use of PKI
useClientPKI = True;
# let the user know PKI is certs are found
print ("Client certificate found ...")
Modifying the Client
The primary modifications to the client file capture the user commands, such
as addPKI or addDH, and then configure the communications accordingly. Once
we know which encryption method the user wants (plain, PKI, ECC), we pass
the data, the type of encryption, and the required key or client secret. The client
file will pass the heavy lifting over to the helper file:
# handle any custom commands
if data == b'exit':
break
if result == 0:
break
if result == 10:
sendUsingPrivate = False;
if result == 11:
sendUsingPrivate = True;
skipEncryption = True;