Who Are You?

User authentication is handled by the server (more later).

Once a user has logged in with user/password you can get his name and authentication type:

//get the user's name
public String HttpServletRequest.getRemoteUser();

//get the authtype
public String HttpServletRequest.getAuthType();
//it is one of BASIC, DIGEST, FORM, CLIENT-CERT.

These work only after user has been authorized.