Simple JAAS programming

The JAAS-enabled code is partitioned into two groups: the setup code and the user-specific code.

The JAAS Setup Code

The setup code looks like this:

package javasec.samples.ch15;

import javax.security.auth.*;
import javax.security.auth.callback.*;
import javax.security.auth.login.*;

public class CountFiles {

    static class NullCallbackHandler implements CallbackHandler {
        public void handle(Callback[] cb) {
            throw new IllegalArgumentException("Not implemented yet");
        }
    }

    static LoginContext lc = null;
    public static void main(String[] args) {
        // use the configured LoginModules for the "CountFiles" entry
        try {
           lc = new LoginContext("CountFiles",
                                 new NullCallbackHandler(  ));
        } catch (LoginException le) {
            le.printStackTrace(  );
            System.exit(-1);
        } 

        // log in the user
        try {
            lc.login(  );
            // if we return with no exception, authentication succeeded
        } catch (Exception e) {
            System.out.println("Login failed: " + e);
            System.exit(-1);
        }

        // now execute the code as the authenticated user
        Object o =
            Subject.doAs(lc.getSubject(), new CountFilesAction(  ));
        System.out.println("User " + lc.getSubject(  ) + " found " +
                            o + " files.");
        System.exit(0);
    }
}

There are three important steps here: first, we construct a LoginContext object; second, we use that object to log in a user; and third, we pass that user as one of the parameters to the doAs( ) method.

The LoginContext class

The first two of these activities are based on the LoginContext class (javax.security.auth.login.LoginContext ...

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