Newsletter sign-up
View all newsletters

Enterprise Java Newsletter
Stay up to date on the latest tutorials and Java community news posted on JavaWorld

Sponsored Links

Optimize with a SATA RAID Storage Solution
Range of capacities as low as $1250 per TB. Ideal if you currently rely on servers/disks/JBODs

JavaWorld.com > Java Enterprise Edition >

All that JAAS

Scalable Java security with JAAS

By John Musser and Paul Feuer, JavaWorld.com, 09/13/02

  • Print
  • Feedback
. What's this?

Page 4 of 6

The last element here, credential, is not a class or an interface, but can be any object. Credentials can include any authentication artifact, such as a ticket, key, or password, that specific security systems might require. The Subject class maintains unique Sets of private and public credentials, which can be retrieved with methods such as getPrivateCredentials() and getPublicCrendentials(). These methods are more often used by security subsystems than at the application layer.

Authentication: LoginContext

Your application layer uses LoginContext as its primary class for authenticating Subjects. LoginContext also represents where JAAS's dynamic pluggability comes into play, because when you construct a LoginContext, you specify a named configuration to load. The LoginContext typically loads the configuration information from a text file, which in turn tells the LoginContext which LoginModules to use during login.

The three commonly used methods in LoginContext are:

Table 2. LoginContext methods
login() Performs login, a relatively complex step that invokes all LoginModules specified for this configuration. If it succeeds, it creates an authenticated Subject. If it fails, it throws a LoginException.
getSubject() Returns the authenticated Subject.
logout() Logs out the authenticated Subject and removes its Principals and credentials.


We will show how to use these methods later.

Authentication: LoginModule

LoginModule is the interface to specific authentication mechanisms. J2SE 1.4 ships with a set of ready-to-use LoginModules, including:

Table 3. LoginModules in J2SE 1.4
JndiLoginModule Verifies against a directory service configured under JNDI (Java Naming and Directory Interface)
Krb5LoginModule Authenticates using Kerberos protocols
NTLoginModule Uses the current user's NT security information to authenticate
UnixLoginModule Uses the current user's Unix security information to authenticate


Along with these modules comes a set of corresponding concrete Principal implementations in the com.sun.security.auth package, such as NTDomainPrincipal and UnixPrincipal.

The LoginModule interface has five methods:

Table 4. LoginModule methods
initialize() Called after the LoginModule is constructed.
login() Performs the authentication.
commit() Called by the LoginContext after it has accepted the results from all LoginModules defined for this application. We assign Principals and credentials to the Subject here.
abort() Called when any LoginModule for this application fails (even though earlier ones in sequence may have succeeded—thus akin to a 2PC model). No Principals or credentials are assigned to the Subject.
logout() Removes the Principals and credentials associated with the Subject.


The application layer calls none of these methods directly—the LoginContext invokes them as needed. Our example below will elaborate on these methods' implementations.

Authentication: CallbackHandlers and Callbacks

CallbackHandlers and Callbacks let a LoginModule gather necessary authentication information from a user or system, while remaining independent of the actual interaction mechanism. We'll leverage that capability in our design—our RdbmsLoginModule does not depend on how the user credentials (username/password) are obtained and can thus be used in the different application environments we will illustrate (either from the command line or from a JSP).

  • Print
  • Feedback
What is Tech Briefcase?
TechBriefcase is a new, free service where IT Professionals can Search, Store and Share IT white papers and content like this. Learn more
Bookmark content
Speed up your research efforts with content across the web.
Search and Store
Find the white papers you need. Create folders for any topic.
View Anywhere
Open your briefcase on your iPhone, tablet or desktop. Share with colleagues.
Don't have an account yet?

Resources