import base64
import hashlib
from Crypto import Random
from Crypto.Cipher import AES
 
class AESCipher(object):
 
   def __init__(self, key):
      self.bs = 32
      self.key = hashlib.sha256(key.encode()).digest()
 
   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:])]
 
 
key = 'test'
AES_test = AESCipher(key)
 
enc = AES_test.encrypt('how are you?')
print "Let\'s encrypt plain text \"How are you?\" -> " + enc
dec = AES_test.decrypt(enc)
print "Let\'s decrypt cipher text -> " + dec

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