code: def get_crypt_class(self):
          
          crypt_type = getattr(settings, 'ENCRYPTED_FIELD_MODE', 'DECRYPT_AND_ENCRYPT')
          if crypt_type == 'ENCRYPT':
              crypt_class_name = 'Encrypter'
          elif crypt_type == 'DECRYPT_AND_ENCRYPT':
              crypt_class_name = 'Crypter'
          else:
              raise ImproperlyConfigured(
                  'ENCRYPTED_FIELD_MODE must be either DECRYPT_AND_ENCRYPT '
                  'or ENCRYPT, not %s.' % crypt_type)
          return getattr(keyczar, crypt_class_name)
docs: Get the Keyczar class to use.
  
          The class can be customized with the ENCRYPTED_FIELD_MODE setting. By default,
          this setting is DECRYPT_AND_ENCRYPT. Set this to ENCRYPT to disable decryption.
          This is necessary if you are only providing public keys to Keyczar.
  
          Returns:
              keyczar.Encrypter if ENCRYPTED_FIELD_MODE is ENCRYPT.
              keyczar.Crypter if ENCRYPTED_FIELD_MODE is DECRYPT_AND_ENCRYPT.
  
          Override this method to customize the type of Keyczar class returned.