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amy.py
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amy.py
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from AESCipher import AESCipher, BS
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
from Crypto.Signature import PKCS1_PSS
from Crypto.Hash import MD5
import socket
import sys
import pickle
import os
import hashlib
CA_PUBLIC_KEY_FILE = 'berisign-python.pub'
RECEIVER_NAME = 'bryan'
OUTPUT_FILE = 'msgs.txt'
BUFFER_SIZE = 1024
class Amy():
def __init__(self, host, port):
self.session_key = self.generate_random_key()
self.host = host
self.port = port
self.socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
self.socket.connect((host, port))
self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.aes = AESCipher(self.session_key)
@staticmethod
def generate_random_key():
return os.urandom(BS)
def encrypt_session_key(self, public_key):
self.encrypted_session_key = public_key.encrypt(self.session_key)
def send_message(self, message):
lol = pickle.dumps(message)
self.socket.send(lol)
pass
def receive_message(self):
return self.socket.recv(BUFFER_SIZE)
def read_ca_public_key(self):
with open(CA_PUBLIC_KEY_FILE, "r") as f:
content = f.read()
return content
def get_public_key(self, public_key_content):
return PKCS1_OAEP.new(RSA.importKey(public_key_content))
def get_ca_public_key(self, public_key_content):
return PKCS1_PSS.new(RSA.importKey(public_key_content))
def receive_all_message(self):
messages = ''
while(True):
message = self.receive_message()
if (len(message) == 0):
break
messages += message
return messages
def decode_message(self, messages):
message_list = messages.split(".")
full_message = ''
for message in message_list:
if (len(message) == 0):
break
real_message = pickle.loads(message+'.')
full_message += self.aes.decrypt(real_message)
return full_message
def write_to_file(self, message):
with open(OUTPUT_FILE, 'w') as f:
f.seek(0)
f.truncate()
f.write(message)
def verify(self, name, public_key_content, signature, ca_public_key):
md5 = MD5.new()
md5.update(name)
md5.update(public_key_content)
return ca_public_key.verify(md5, signature)
def connect(self):
# receive bryan public key
public_key_content = pickle.loads(self.receive_message())
public_key = self.get_public_key(public_key_content)
# receive signature
signature = pickle.loads(self.receive_message())
# get CA public key from file
ca_public_key = self.get_ca_public_key(self.read_ca_public_key())
if (self.verify(RECEIVER_NAME, public_key_content, signature, ca_public_key)):
# encrypt session key
self.encrypt_session_key(public_key)
# send encrypted session key
self.send_message(self.encrypted_session_key)
# receive all message
messages = self.receive_all_message()
# get plaintext message
messages = self.decode_message(messages)
# write to file
self.write_to_file(messages)
else:
print 'Error:MD5 signature does not match'
# close socket
self.socket.close()
if __name__ == '__main__':
HOST = sys.argv[1]
PORT = int(sys.argv[2])
amy = Amy(HOST, PORT)
amy.connect()