import hashlib
import base64
from Crypto.Cipher import AES


class AESCipher(object):
    def __init__(self, key):
        self.bs = AES.block_size
        self.key = hashlib.sha256(AESCipher.str_to_bytes(key)).digest()

    @staticmethod
    def str_to_bytes(data):
        u_type = type(b"".decode("utf8"))
        if isinstance(data, u_type):
            return data.encode("utf8")
        return data

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

    def decrypt(self, enc):
        iv = enc[: AES.block_size]
        cipher = AES.new(self.key, AES.MODE_CBC, iv)
        return self._unpad(cipher.decrypt(enc[AES.block_size :]))

    def decrypt_string(self, enc):
        enc = base64.b64decode(enc)
        return self.decrypt(enc).decode("utf8")

if __name__ == "__main__":
    encrypt = "P37w+VZImNgPEO1RBhJ6RtKl7n6zymIbEG1pReEzghk="
    cipher = AESCipher("test key")
    print("明文:\n{}".format(cipher.decrypt_string(encrypt)))