code: def _decrypt_masterpassword(self):
          
          aes = AESCipher(self.password)
          checksum, encrypted_master = self.config[self.config_key].split("$")
          try:
              decrypted_master = aes.decrypt(encrypted_master)
          except Exception:
              self._raise_wrongmasterpassexception()
          if checksum != self._derive_checksum(decrypted_master):
              self._raise_wrongmasterpassexception()
          self.decrypted_master = decrypted_master
docs: Decrypt the encrypted masterkey