import random
import getpass
from Crypto import Random
from Crypto.Hash import SHA256
from Crypto.Cipher import AES

def decrypt(s_enc, key_hash):
    iv = s_enc[0:AES.block_size]
    s_enc = s_enc[AES.block_size:]
    cipher = AES.new(key_hash, AES.MODE_CBC, iv)
    return cipher.decrypt(s_enc)

def encrypt(s, key_hash):
    iv = Random.new().read(AES.block_size)
    cipher = AES.new(key_hash, AES.MODE_CBC, iv)
    extra = len(s) % 16
    if extra > 0:
        s = s + (b' ' * (16 - extra))
    s_enc = iv + cipher.encrypt(s) # prepend IV
    return s_enc