Echo-Server.py

import socket
import sys
from Crypto.Cipher import AES

HOST = '127.0.0.1'  # Standard loopback interface address (localhost)
PORT = 65432        # Port to listen on (non-privileged ports are > 1023)

# Create a TCP/IP socket
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# Bind the socket to the port
server_address = (HOST, PORT)
print >>sys.stderr, 'starting up on %s port %s' % server_address
s.bind(server_address)

# Listen for incoming connections
s.listen(1)

# Encryption of message
def do_encrypt(message):
    obj = AES.new('This is a key123', AES.MODE_CBC, 'This is an IV456')
    ciphertext = obj.encrypt(message)
    return ciphertext

# Decryption of message
def do_decrypt(ciphertext):
    obj2 = AES.new('This is a key123', AES.MODE_CBC, 'This is an IV456')
    message = obj2.decrypt(ciphertext)
    return message

while True:
    # Wait for a connection
    print >>sys.stderr, 'waiting for a connection'
    connection, client_address = s.accept()
    try:
        print >> sys.stderr, 'connection from', client_address

        # Receive the data in small chunks and retransmit it
        while True:
            data = connection.recv(16)
            print >> sys.stderr, 'received "%s"' % data
            if data:
                print >> sys.stderr, 'sending data back to the client'
                connection.sendall(data)
            else:
                print >> sys.stderr, 'no more data from', client_address
                break

    finally:
        # Clean up the connection
        connection.close()