99 lines
2.9 KiB
Python
99 lines
2.9 KiB
Python
#!/usr/bin/env python3
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import socket
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from Crypto.Cipher import AES
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from binascii import hexlify, unhexlify
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import random
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from Crypto.PublicKey import ECC
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HOST = 'localhost'
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PORT1 = 20206
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PORT2 = 20306
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def debug_secure_channel(s1, s2, data):
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data = data.rstrip('\n') # remove trailing newline
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if len(data) >= 1024:
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print("from {} to {}: `{}...'".format(s1, s2, data[:1024]))
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else:
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print("from {} to {}: `{}'".format(s1, s2, data))
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iv, ciphertext, mac = data.split(";")
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assert (len(iv) == 16 * 2) # a hexlified byte is two bytes long, the IV should be 16 bytes
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assert (len(ciphertext) % (16 * 2) == 0) # a hexlified byte is two bytes long, AES block size is 128 bit (16 byte)
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assert (len(mac) == 16 * 2) # a quite short MAC. Hint: you still don't want to brute force it!
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print("relayed {} encrypted blocks of payload".format(len(unhexlify(ciphertext)) // AES.block_size))
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def main():
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s1 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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s1.connect((HOST, PORT1))
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s1f = s1.makefile("rw") # file abstraction for the sockets
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s2 = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
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s2.connect((HOST, PORT2))
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s2f = s2.makefile("rw")
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# First step of Diffie Hellman (compare slides)
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data = s1f.readline()
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print("from s1 to s2: '{}'".format(data)) # you should see the newline at the end printed
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p, g, X = data.split(",")
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p = int(p)
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g = int(g)
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X = int(X)
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print("p: {} g: {} X: {}".format(p, g, X))
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a = random.randint(1, p-1)
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eve_X = pow(g, a, mod=p)
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eve_data = f"{p},{g},{eve_X}\n"
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# # forward to Bob
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s2f.write(eve_data)
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s2f.flush()
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# # # Receive answer (second step of DH)
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data = s2f.readline()
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print("from s2 to s1: '{}'".format(data))
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# # # Forward received
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# s1f.write(data) # the data should still have a b'\n' at the end
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# s1f.flush()
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# # # Alice sends something to Bob
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# data = s1f.readline()
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# print("S1f {}".format(data))
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# debug_secure_channel("Alice", "Bob", data)
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# # # Forward received data to Bob
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# s2f.write(data)
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# s2f.flush()
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# data = s2f.readline()
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# debug_secure_channel("Bob", "Alice", data)
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# print(f"get data from bob: {data}")
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# s1f.write(data)
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# s1f.flush()
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# data = s1f.readline()
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# debug_secure_channel("Bob", "Alice", data)
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# print(f"get data from alice: {data}")
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# # "alice sending hey bob, plz send me my f14g"
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# s2f.write(data)
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# s2f.flush()
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# data = s1f.readline()
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# print(f"get data from alice: {data}")
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# s2f.write(data)
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# s2f.flush()
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# data = s2f.readline()
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# print(f"get data from bob :{data}")
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# s1f.write(data)
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# s1f.flush()
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# data = s1f.readline()
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# print(f"get data from alice again: {data}")
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s1f.close()
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s2f.close()
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s1.close()
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s2.close()
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if __name__ == "__main__":
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main()
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