def echo_message(self, encrypted_message, iv):
cipher = AES.new(self.aes_key, AES.MODE_CBC, iv)
padded_message = cipher.decrypt(encrypted_message)
message = unpadder(padded_message)
print("{} relayed message: {}".format(self.name, message))
recipient_message, recipient_iv = self.recipient.echo_message(
encrypted_message, iv)
recipient_cipher = AES.new(self.aes_key, AES.MODE_CBC, recipient_iv)
decrypted_recipient_message = unpadder(
recipient_cipher.decrypt(recipient_message))
print("{} relayed message: {}".format(self.name,
decrypted_recipient_message))
return recipient_message, recipient_iv
def decrypt(ciphertext_bytearr, key):
iv = key
cipher = AES.new(key, AES.MODE_CBC, iv)
ciphertext_bytearr = bytes(ciphertext_bytearr)
padded_plaintext_bytearr = cipher.decrypt(ciphertext_bytearr)
plaintext_bytearr = unpadder(padded_plaintext_bytearr)
for b in plaintext_bytearr:
if b > 127:
return False, plaintext_bytearr
return True, plaintext_bytearr
def echo_message(self, encrypted_message, iv):
cipher = AES.new(self.aes_key, AES.MODE_CBC, iv)
padded_message = cipher.decrypt(encrypted_message)
message = unpadder(padded_message)
print("{} received message: {}".format(self.name, message))
return_iv = bytes(
[random.randint(0, 255) for _ in range(len(self.aes_key))])
return_cipher = AES.new(self.aes_key, AES.MODE_CBC, return_iv)
return return_cipher.encrypt(padder(message,
len(self.aes_key))), return_iv
def send_message(self, message, partner):
print("{} sending message: {}".format(self.name, message))
padded_message = padder(message, len(self.aes_key))
iv = bytes([random.randint(0, 255) for _ in range(len(self.aes_key))])
cipher = AES.new(self.aes_key, AES.MODE_CBC, iv)
encrypted_message = cipher.encrypt(padded_message)
echoed_message, partner_iv = partner.echo_message(
encrypted_message, iv)
partner_cipher = AES.new(self.aes_key, AES.MODE_CBC, partner_iv)
decrypted_echoed_message = unpadder(
partner_cipher.decrypt(echoed_message))
assert decrypted_echoed_message == message, "sent and echoed message differ do not match! sent: {} echoed: {}".format(
message, decrypted_echoed_message)
if __name__ == "__main__":
plaintext = "The quick brown fox jumps over the lazy dog"
plaintext_bytearray = plaintext.encode("utf-8")
key = "YELLOW SUBMARINE"
iv = bytearray(len(key))
padded_plaintext_bytearray = padder(plaintext_bytearray, len(key))
print("Plaintext: {}".format(plaintext))
ciphertext = encrypt(padded_plaintext_bytearray, iv, key)
print("Ciphertext: {}".format(ciphertext))
recreated_plaintext = decrypt(ciphertext, iv, key)
unpadded_recreated_plaintext = unpadder(recreated_plaintext)
print("Recreated plaintext: {}".format(unpadded_recreated_plaintext))
assert plaintext_bytearray == unpadded_recreated_plaintext, "plaintext and recreated_plaintext do not match!"
"""
## DECRYPT GIVEN TEXT FILE
with open("set2/data_ch_2.txt", "r") as f:
ciphertext_bytearr = b64decode("".join(f.read().strip().split("\n")))
key = "YELLOW SUBMARINE"
iv = bytearray(len(key))
plaintext = decrypt(ciphertext_bytearr, iv, key)
print(plaintext)
"""
def decrypt_profile(ciphertext, key):
cipher = AES.new(bytes(key), AES.MODE_ECB)
decrypted_cookie = unpadder(cipher.decrypt(ciphertext))
decrypted_profile = parse_cookie(decrypted_cookie.decode("utf-8"))
return decrypted_profile