#-*- coding: utf-8 -*-
# (c) 2012 Anders Andersen
# See http://www.cs.uit.no/~aa/dist/tools/py/COPYING for details

# Load modules
import sys
from noop.ip.tcp import *
from hashlib import sha256
from Crypto import Random
from Crypto.Cipher import AES
from Crypto.Util import Counter

# Read arguments (host, port and password)
host = "localhost"
port = 3456
passwd = "pw"
if len(sys.argv) > 1:
    host = sys.argv[1]    
if len(sys.argv) > 2:
    port = int(sys.argv[2])
if len(sys.argv) > 3:
    passwd = sys.argv[3]

# A class to receive encrypted data
class SecComReceive:
    
    # Save address and password based key
    def __init__(self, address, pwd):
        self.addr = address
        self.key = sha256(pwd.encode()).digest()
        self._first_time = True

    # Receive cipher text and decrypt it
    def receive(self):
        if self._first_time:
            self._first_time = False
            tmp = tcpreceive(self.addr)
            while len(tmp) < AES.block_size:
                tmp += tcpreceive(self.addr)
            self.irv = tmp[:AES.block_size]
            data = tmp[AES.block_size:]
            ctr = Counter.new(
                AES.block_size*8,
                initial_value=int.from_bytes(self.irv, 'little'))
            self.cipher = AES.new(self.key, AES.MODE_CTR, counter=ctr)
        if not len(data) > 0:
            data = tcpreceive(self.addr)
        return self.cipher.decrypt(data)

# Create object to receive data from client, and then receive the data
scr = SecComReceive(IPaddr(node=host, port=port), passwd)
print(scr.receive().decode())