one of them Plack::Middleware::Auth::Basic allows you to quickly implement an authorization layer.

I think Plack::Middleware::Auth::Basic is specifically for the Basic Authentication scheme (i.e. the "standard" one), described in RFC2617 section 2, while Plack::Middleware::Auth::Digest is for the Digest Authentication scheme (what I suppose the OP is looking for), described in RFC2617 section 3.