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

class AESCipher(object):
  """ Helper class for encrypting and decrypting data via AES.

      Copied From: http://stackoverflow.com/a/21928790
  """
  def __init__(self, key):
    self.bs = 32
    self.key = key

  def encrypt(self, raw):
    raw = self._pad(raw)
    iv = Random.new().read(AES.block_size)
    cipher = AES.new(self.key, AES.MODE_CBC, iv)
    return base64.b64encode(iv + cipher.encrypt(raw))

  def decrypt(self, enc):
    enc = base64.b64decode(enc)
    iv = enc[:AES.block_size]
    cipher = AES.new(self.key, AES.MODE_CBC, iv)
    return self._unpad(cipher.decrypt(enc[AES.block_size:])).decode('utf-8')

  def _pad(self, s):
    return s + (self.bs - len(s) % self.bs) * chr(self.bs - len(s) % self.bs)

  @staticmethod
  def _unpad(s):
    return s[:-ord(s[len(s)-1:])]