Catalyst::Authentication::Credential::HTTP lets you use HTTP
 authentication with Catalyst::Plugin::Authentication. Both basic and
 digest authentication are currently supported.
 .
 When authentication is required, this module sets a status of 401, and
 the body of the response to 'Authorization required.'. To override this
 and set your own content, check for the "$c->res->status == 401" in
 your "end" action, and change the body accordingly.