testAES256.py

from Crypto import Random
from Crypto.Cipher import AES
import base64
import hashlib

BLOCK_SIZE = 16

# MODES CFB,CBC XTS


def encrypt(message, passphrase, mode, IV):
    # passphrase MUST be 16, 24 or 32 bytes long, how can I do that ?
    aes = AES.new(passphrase, mode, base64.b64decode(IV))
    return base64.b64encode(aes.encrypt(message))


def decrypt(encrypted, passphrase, mode, IV):
    # IV = Random.new().read(BLOCK_SIZE)
    aes = AES.new(passphrase, mode, base64.b64decode(IV))
    return aes.decrypt(base64.b64decode(encrypted))


def makekey(password):
    return hashlib.sha256(hashlib.sha256(password).digest()).digest()


def makeIV():
    IV = Random.new().read(BLOCK_SIZE)
    return base64.b4encode(IV)


def test():
    print("password = a")
    input_str = "0123456789ABCDEF0123456789ABCDEF"
    print("input message =", input_str)

    key = makekey("a")
    print("key = double hashed password =", key.encode("hex"))

    mode = AES.MODE_CBC
    print("MODE = ", mode)

    IV, enc = encrypt(input_str, key, mode, IV)
    print("IV =", IV, ",encrypted message =", enc)

    dec = decrypt(enc, key, mode, IV)
    print("decrypted message = ", dec)


test()