server.py

# import socket library 
import socket 

# import threading library 
import threading 
import crypt
# Choose a port that is free 
PORT = 8721

# An IPv4 address is obtained 
# for the server. 
SERVER = socket.gethostbyname(socket.gethostname()) 

# Address is stored as a tuple 
ADDRESS = (SERVER, PORT) 

# the format in which encoding 
# and decoding will occur 
FORMAT = "utf-8"
n, z, totient1, totient2, public_key1, private_key1, public_key2, private_key2,p,q,r,s = crypt.runRSA(10)
print('public key1: ' + str(public_key1) + ' n1: ' + str(n) + ' public key2: ' + str(public_key2) + ' n2: ' + str(z))
# Lists that will contains 
# all the clients connected to 
# the server and their names. 
global clients, names
global public_key1_clients, public_key2_clients
global n1_clients, n2_clients
clients, names = [], [] 
public_key1_clients, public_key2_clients = [] , []
n1_clients, n2_clients = [], []


# Create a new socket for 
# the server 
server = socket.socket(socket.AF_INET, 
					socket.SOCK_STREAM) 

# bind the address of the 
# server to the socket 
server.bind(ADDRESS) 

# function to start the connection 
def startChat(): 
	
	print("server is working on " + SERVER) 
	
	# listening for connections 
	server.listen() 
	
	while True: 
		
		# accept connections and returns 
		# a new connection to the client 
		# and the address bound to it 
		conn, addr = server.accept() 
		conn.sendall(str.encode("\n".join([str(public_key1), str(n),str(public_key2),str(z)])))
		rec = conn.recv(1024).decode(FORMAT)
		public_key1_client, n_client,public_key2_client,z_client = [int(i) for i in conn.recv(1024).decode('utf-8').split('\n')]
		# 1024 represents the max amount 
		# of data that can be received (bytes)
		conn.send("NAME".encode(FORMAT))
		name = conn.recv(1024).decode(FORMAT) 
		
		# append the name and client 
		# to the respective list 
		names.append(name) 
		clients.append(conn) 
		public_key1_clients.append(public_key1_client) 
		public_key2_clients.append(public_key2_client)
		n1_clients.append(n_client) 
		n2_clients.append(z_client)
		

		print(f"Name is :{name}") 
		
		# broadcast message 
		broadcastMessage(f"{name} has joined the chat!") 
		
		conn.send('Connection successful!'.encode(FORMAT)) 
		
		# Start the handling thread 
		thread = threading.Thread(target = handle, 
								args = (conn, addr)) 
		thread.start() 
		
		# no. of clients connected 
		# to the server 
		print(f"active connections {threading.activeCount()-1}") 

# method to handle the 
# incoming messages 
def handle(conn, addr): 
	
	print(f"new connection {addr}") 
	connected = True
	
	while connected: 
		# recieve message 
		message = conn.recv(1024).decode(FORMAT)
		# print(message)
		message = message[(message.index('[') + 1):]
		message = message[:message.index(']')]
		message = [i.strip() for i in message.split(',')]
		message = [i[1:] for i in message]
		message = [i[:-1] for i in message]
		message = [int(i) for i in message]
		# print(message)
		# broadcast message 
		de = crypt.decrypt(message,private_key1,private_key2,p,q,r,s,z)
		# print(de)
		broadcastMessage(''.join(de))
		
		# close the connection 
	conn.close() 

# method for broadcasting 
# messages to the each clients 
def broadcastMessage(message): 
	i = 0
	for client in clients:
		msg = crypt.encrypt(message,public_key1_clients[i],public_key2_clients[i],n1_clients[i],n2_clients[i])
		client.send(f"{msg}".encode(FORMAT)) 
		i = i + 1

# call the method to 
# begin the communication 
startChat()