def main():
key = b'YELLOW SUBMARINE'
initialisation_vector = bytes(16 * [0])
cipher = AES_CBC(key, initialisation_vector)
assert cipher.decrypt(
loadChallengeData())[:33] == b"I'm back and I'm ringin' the bell"
def main():
prime = 0xffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6df25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece45b3dc2007cb8a163bf0598da48361c55d39a69163fa8fd24cf5f83655d23dca3ad961c62f356208552bb9ed529077096966d670c354e4abc9804f1746c08ca237327ffffffffffffffff
for base in [1, prime, prime - 1]:
messages = simulate_communication_with_dh_key(prime, base)
if base == prime:
secret_key = 0
else:
secret_key = 1
aes_key = SHA1(bso.int_to_bytes(secret_key)).digest()[:16]
malcolm = AES_CBC(aes_key, b'0'*16)
assert bso.remove_padding_pkcs7(malcolm.decrypt(messages[0][:-16], messages[0][-16:])) == b'Message to Bob'
assert bso.remove_padding_pkcs7(malcolm.decrypt(messages[1][:-16], messages[1][-16:])) == b'Message to Alice'
def main():
"""Simulate a man in the middle attack on Diffie Hellman key exchange"""
prime = 0xffffffffffffffffc90fdaa22168c234c4c6628b80dc1cd129024e088a67cc74020bbea63b139b22514a08798e3404ddef9519b3cd3a431b302b0a6df25f14374fe1356d6d51c245e485b576625e7ec6f44c42e9a637ed6b0bff5cb6f406b7edee386bfb5a899fa5ae9f24117c4b1fe649286651ece45b3dc2007cb8a163bf0598da48361c55d39a69163fa8fd24cf5f83655d23dca3ad961c62f356208552bb9ed529077096966d670c354e4abc9804f1746c08ca237327ffffffffffffffff
base = 2
connection = diffiehellman_mitm_sim(prime, base)
# intercept alices public key
prime, base, _ = next(connection)
# send prime instead of alices public key to bob. Recieve Bobs public key,
# which we forget as it is not needs. The shared kill will be 0.
connection.send((prime, base, prime))
#Send prime as bob's public key to alice. We have ensured that the shared
#hared secret key is 0. Recieve Alice's ciphertext for bob
ciphertext_a2b = connection.send(prime)
# decrypt
malcolm = AES_CBC(SHA1(bso.int_to_bytes(0)).digest()[:16], b'0' * 16)
messages = []
messages.append(
bso.remove_padding_pkcs7(
malcolm.decrypt(ciphertext_a2b[:-16], ciphertext_a2b[-16:])))
#Send the ciphertext to bob. Recieve his response
ciphertext_b2a = connection.send(ciphertext_a2b)
messages.append(
bso.remove_padding_pkcs7(
malcolm.decrypt(ciphertext_b2a[:-16], ciphertext_b2a[-16:])))
assert messages[0] == b'Message to Bob'
assert messages[1] == b'Message to Alice'
return
def decrypt(self, ciphertext):
plaintext = AES_CBC.decrypt(self, ciphertext)
plaintext = bso.remove_padding_pkcs7(plaintext)
return plaintext