from Crypto.Cipher import AES
from Crypto.Util.strxor import strxor
from binascii import hexlify
from Crypto.Random import get_random_bytes

# Random generation
K = get_random_bytes(AES.block_size)
cipher = AES.new(K, AES.MODE_CBC)

# Original Message
M1 = K #bytes(K,encoding="utf-8")
M2 = K #bytes(K,encoding="utf-8")

Cm0 = cipher.encrypt(('\0' * AES.block_size).encode("utf-8"))
Cm1 = cipher.encrypt(strxor(Cm0, M1))

Tm = Cm2 = cipher.encrypt(strxor(Cm1, M2))
N1 = get_random_bytes(AES.block_size)#'qwertyuiop'.encode("utf-8")

# Inject second message after the first message
Cx0 = cipher.encrypt(('\0' * AES.block_size).encode("utf-8"))
Cx1 = cipher.encrypt(strxor(Cx0, M1))
Cx2 = cipher.encrypt(strxor(Cx1, N1))

# X needs to *encrypt* to the same value as Cm1
#X = strxor(cipher.decrypt(Cx1), Cx2)
X = strxor(strxor(Cx0, M1), Cx2)
Cx3 = cipher.encrypt(strxor(Cx2, X))
Tx = Cx4 = cipher.encrypt(strxor(Cx3, M2))

# MAC should be same here
print("Tm = '%s'" % hexlify(Tm))
print("Tx = '%s'" % hexlify(Tx))