Digest Authentication on Phil's REST server

[eluser]alexanderm[/eluser]
Using Digest authentication with Phil Sturgeon's REST server.

Can it authenticate at any more granular level than just grant/deny access at the API level? (That was really easy to get working.)

Is there a call I can make at the beginning of a controller method to see whether the given credentials are valid for that particular call?

If not, please suggest a good, simple framework I could use. I'm just building an API, not web pages.

Thank you.