Welcome!

Java IoT Authors: Liz McMillan, Pat Romanski, Yeshim Deniz, Elizabeth White, Kong Yang

Related Topics: Java IoT

Java IoT: Article

Extending JAAS

Extending JAAS

User authentication and access control are important security measures for most Java applications, especially J2EE applications. The Java Authentication and Authorization Service (JAAS), the core API of J2SE 1.4 and 1.5, represents the new security standard. It provides a pluggable and flexible framework that allows developers to incorporate different security mechanisms and various security sources.

With the upcoming release of J2SE 1.5, which includes a lot of enhancements to cryptography, XML security, Public Key Infrastructure (PKI), Kerberos, and the federating identity, the JAAS will play a more important role in J2EE security implementations.

Overview of JAAS
Authentication

Authentication is the process of verifying that a user has the right to use identities established by the enterprise user registry. The authentication mechanism of JAAS is built on a set of pluggable modules (see Figure 1). JAAS allows different authentication models to be plugged in at runtime. The client applications always interact with JAAS through the LoginContext object.

The authentication process typically involves the following steps:

  1. Create a LoginContext object. The LoginContext looks up the configuration file to determine which LoginModule to use. Also, optionally, you can pass a CallbackHandler to the LoginContext.
  2. Perform authentication by calling the login method of LoginContext, which loads the predefined LoginModule to check if the user can be authenticated.
  3. Associate principals and credentials with the Subject if the user is authenticated.
  4. Or throw a LoginException in case login failed.
  5. Use the logout method of LoginContext to log out.
The login in JAAS is a two-phase process. The first phase is the "login" phase (as described in step 2). The only task in this phase is authentication. Once the process successfully passes this phase, the authentication process enters the "commit" phase (step 3) in which the commit method of LoginModule is called to associate the relevant principals and credentials with the Subject.

A Subject in JAAS represents an authenticated entity, such as a person or device. It contains a set of principals and security-related attributes such as a password and cryptographic keys. In the JAAS architecture, the Subject, along with the Permission, plays an important role in the authorization process.

Of all the authentication modules, the LoginModule is the interface to a particular authentication mechanism. Although the LoginModule never gets called directly by the client application, it provides a particular type of authentication via a pluggable module, which implements the authentication algorithm and determines how the actual authentication is performed. Sun provides a few default LoginModule implementations, such as JndiLoginModule, Krb2LoginModule, UnixLoginModule, and NTLoginModule under the package of sun.com.security.auth .module. Since the JAAS login architecture is extensible, you can pretty much "plug in" any LoginModule just by specifying which LoginModule to use in the configuration file. An example of a configuration file looks like this:


MySample {
com.sample.module.MyLoginModule required debug=true;
};

Here MySample is the name of the login context, which is passed into the LoginContext constructor when you create a new LoginContext to start the authentication process, followed by the configuration block. The block informs JAAS about the loginModule that should be used to perform authentication during the login. In addition to the LoginModule, any options to that LoginModule can also be specified here.

During the login step, the CallbackHandler is used by LoginModule to communicate with the user to obtain authentication information. The CallbackHandler handles three types of Callbacks: NameCallback, which prompts the user for a user name; PasswordCallback, which prompts for a password; and TextOutputCallback, which reports any error, warning, or other messages sent to the user.

Authorization

Authorization is the process of determining whether an authenticated user is permitted to perform some actions, such as accessing a resource. The process is policy-based since JAAS is built on the existing Java security model. The policy configuration file essentially contains a list of entries, such as "keystore" and/or "grant". The grant entry includes all the permissions granted for the authenticated codes or principals to do the security-sensitive operations, for instance, accessing a particular Web page or local file. JAAS supports principal-based policy entry. Permissions can be granted in the policy to specific principals.

The basic format of a grant entry looks like this:

grant Codebase "codebase_URL" Signedby "signer_name,"
Principal principal_class_name "principal_name",
Principal principal_class_name "principal_name",
S {
permission permission_class_name "target_name", "action",
permission permission_class_name "target_name", "action",
S
}
The "action" may be required or can be omitted depending on the permission type.

In the JAAS architecture, the Policy object represents the system security policy for a Java application environment and there's only one Policy object in effect at any time according to the Java 2 SDK document. The default implementation of Policy is sun.security.provider.PolicyFile, in which the policies are specified within one or more policy configuration files.

Once the user is authenticated, the authorization takes place via the Subject.doAs method, or the static doAsPrivileged method from Subject class. The doAs method dynamically associates the subject with the current AccessControlContext and then invokes the run method to execute the action, which causes the security checks. The permission check process goes through the following steps illustrated in Figure 2:

  1. Invoke Subject.doAs (or doAsPrivileged).
  2. Call SecurityManager.checkPermission or other check methods to check the permission.
  3. The SecurityManager delegates the check to the AccessController.
  4. The AccessController ensures the relevant AccessControlContext contains sufficient permissions for the action to be taken.
  5. The SecurityManager updates the current AccessControlContext with the permissions granted to the subject via the Policy from the policy file.
If the required permission to a specific principal is granted, the operation will be allowed. Otherwise, an Access- ControlException will be thrown.

Like the LoginModule, the Policy is also a pluggable module. You can hook up other Policy implementations by changing "policy.provider=sun.security.provider.PolicyFile" in the java.security properties file to a value of the Policy class you want to use.

Extend JAAS
JAAS is built on top of the existing Java security model, which is CodeSource-based, and the plaintext format policy file implementation. This may not be enough for the enterprise application. You may want to use custom security repositories with JAAS, such as LDAP (lightweight directory access protocol), database, or another file system. It can be done by writing your own customized modules, thanks to the JAAS pluggable feature. However, this would require a good understanding of the modules and processes involved in JAAS, and you need to do a lot of coding to override the proper classes and take care of both the configure and policy files.

Ideally, we'd like to able to extend JAAS in an easier way so whenever a custom security repository or different access control mechanism changed or needed to add, you could just develop and plug in the different small modules (namely, the adapters) to accommodate these new changes or requirements, and best of all, without having to understand or know the details of the JAAS process. Also, we would like to be able to make this change simply by changing a configuration file. Another goal is that our JAAS extension component could be used in different J2EE applications - stand-alone or Web. Figure 3 outlines the design of our JAAS extension component.

Our JAAS extension component takes advantage of the JAAS pluggable architecture by implementing our customized LoginModule and Policy modules. In these modules, we delegate the data requests to the adapters. Each of these adapters is isolated to simple tasks such as data retrieval, so you can rapidly develop different adapters for different security repositories or algorithms instead of trying to implement different LoginModule or Policy modules, which are far more complex and require more effort.

You can download the complete source code from www.sys-con.com/java/sourcec.cfm".

AuthLoginModule
The AuthLoginModule class is our customized LoginModule implementation. The LoginModule is a pluggable component in the JAAS authentication process and serves two purposes:

  1. Authenticate the user.
  2. Update the Subject with relevant principals and credentials if authentication succeeded.
The LoginModule has five methods to implement. Let's look at the login () method. This method is called to authenticate the Subject and basically does two things:
  1. Obtains the user name and password. Typically, the LoginModule invokes the handle method of the CallbackHandler to get the user name and password.
  2. Verifies the password against the one in the data source.
The LoginModule retrieves the username and password from the Callbacks, which, by default, expect some sort of user interaction. This is fine for a simple demo program or on the command line, but it may not be practical for a J2EE application. For instance, for most Web applications, the user name and password will typically be read from a form. In this case, using JAAS authentication will be difficult. Considering we don't use LoginModule directly, the solution is to implement a customized CallbackHandler, which accepts a username and password and then delivers them to the LoginModule so it doesn't need to prompt the user for the information. Here's how the user information got passed from the JSP or servlet:

String userName = request.getParameter ("user");
String password = request.getParameter("password");
LoginContext context = new LoginContext ("MySample",
new AuthCallbackHandler (userName, password));

Once it has the user name and password at hand, the AuthLoginModule, our customized implementation of LoginModule, instantiates the LoginSourceAdapter via the LoginSourceAdapterFactory and delegates the actual authentication to the source adapter. The adapter is nothing more than a simple class, which pulls down the user information from a particular data source, such as database or LDAP, or some other system.

In the "commit" phase, the AuthloginModule retrieves the relevant information from the LoginSourceAdapter and associates them with the Subject.

LoginSourceAdapter
The LoginSourceAdapter is an interface of source adapter for the authentication. It has four methods for required implementations:

  1. void initialize (Hashtable parameters): The initialize method is called to initialize the adapter with the relevant parameters. The method is called immediately after object creation and prior to any calls to other methods.
  2. boolean authenticate (String userName, char[] password): The authenticate method is called to authenticate the user.
  3. String[] getGroupNames (String userName): The getGroupNames method is called to get the relevant principal information after authentication succeeded.
  4. void terminate (): This method is called when the logout method of LoginModule is invoked. It gives the adapter a chance to do some clean-up work.

The argument for the initialize method is the collection of a key-value pair. It could be the parameters for database connectivity, such as driver, URL, user ID, and password, or other information required for your adapter. You can specify these parameters in the configuration file, which I'll discuss later.

AuthPolicy
Under the JAAS architecture, the security policy is handled by the java.security.Policy class, which establishes the various Permissions granted to a particular CodeSource or Principal. As discussed in the previous section, the default implementation is sun.security.provider.PolicyFile. The PolicyFile uses the plaintext file to establish the mapping between permissions and CodeSource, which may not be good enough for the enterprise application. A centralized system such as a relational database for supporting role-base security would be better.

Obviously, to extend JAAS authorization to handle the different security schemes from different sources, we need to write our own Policy implementation.

The steps to create a customized Policy implementation are:

* Extend java.security.Policy.
* Implement getPermissions ().
* Implement refresh ().

If you look at the implementation of our customized Policy class, you may notice that our AuthPolicy class is derived from the sun.security.provider.PolicyFile instead of java.security .Policy. Why? First, I want to implement the AuthPolicy class as the generic Policy class, which can deal with the default policy file without any adapter plugged in. By deriving from the PolicyFile, we don't need to implement the policy file parsing and other related codes. Also, when the application is running with a Security- Manager enabled, a few permissions, such as doAsPrivileged AuthPermission and read FilePermission (for loading a configuration file), need to be granted in order to execute the JAAS. Sure, these permissions could be stored in the data source, but it might be convenient to put them in the standard Java security policy file. However, for serious development you should implement an adapter to deal with these issues.

Following the same design pattern in the extending authentication, our Policy class delegates the permission requests to the PermissionAdapter.

In the Permissions class, the different Permission is held in its own Permission- Collection instance. If you create a custom Permission class, you need to create your own PermissionCollection, otherwise there's no guarantee that your Permission object will be consulted.

PermissionAdapter
The PermissionAdapter is the interface of the pluggable module for authorization in our JAAS extension component. It evaluates the policy from a particular data source and delivers a PermissionCollection that contains a set of permissions granted. The PermissionAdapter interface has the following methods:

  • void initialize (Hashtable initParams): The initialize method is called to initialize the adapter with the relevant parameter. The method is called immediately and prior to any calls to other methods. Also, it's called when Policy's refresh is invoked.
  • PermissionCollection getPermissions (ProtectionDomain domain): This method is called whenever the Permissions with particular Principals is requested.
As an example, let's look at how to implement a role-based PermissionAdapter. Assume that there are three roles: admin, user, and guest all with different privileges, and all the permission information is stored in the database.

First, in the initialize method, we'll retrieve all the permission information for all roles from the database table and populate them in the collection, e.g., Hashtable.

Next, in the getPermissions method, we'll collect the permissions that relate to the involved Principals (this is the only concern for the role-based access control) and return them. Note that we can get relevant Principals by calling the getPrincipals method of ProtectedDomain. It's so simple, isn't it?

JaasUtil
JaasUtil is the main contact to our JAAS extension component, and it has a constructor that takes the user name and password. There are two key methods:

  1. boolean authenticate()
  2. boolean checkPermission(Subject subject, final Permission perm)
The JaasUtil actually defers the login request to LoginContext and the permission check to SecurityManager.

Listing 1 shows how to use JaasUtil. This code first gets the user name and password from the HttpServletRequest and tries to authenticate the user. Then it checks if this user has permission to access the "editReg.jsp".

Configuration
Now we have our customized implementations of the LoginModule, Policy, and other related modules. These modules can delegate the relevant data requests to the appropriate adapters; so far so good. However, in the JAAS architecture, the LoginModule and Policy are never directly invoked by the application, so how do we know which adapter should be instantiated and how to pass the necessary parameters or information, such as connectivity, to the adapters?

The answer is that the adapters can be dynamically configured by updating an XML configuration file. This XML configuration file consists of two major sections:

1. : This section defines the login source adapter and possible input parameters for authentication.
2. : This section defines the permission adapter and possible input parameters for authorization.

You can specify which LoginSourceAdapter and PermissionAdapter to use. It's also possible to pass additional information to the adapter in the configuration file.

There are two ways to let JaasUtil know where to look for the configuration file:

1. Specify the configuration file via the -Dcom.auth.config command-line switch.
2. Call JaasUtil.setConfigFile (configFile).

When you deploy the JAAS extension component, the customized security Policy class file must be added to Java's jre/lib directory, which will cause the policy class file to be loaded by the bootstrap class loader. Otherwise, it won't be picked up and the default policy class provided by Sun will be used instead, even though you placed the policy class file on the Java class path.

Summary
Extending JAAS is not difficult. The JAAS architecture provides you with the flexibility to customize the authentication and authorization processes. Understanding how these processes work is the first step in knowing how to "roll your own" implementation. In this article, we recalled the basics of the JAAS, and examined the details of how to extend JAAS to be a more dynamic, flexible, and scalable framework. With this extended framework, you can easily create your own login and access control mechanisms to support either your own enterprise-specific security requirements or emerging security standards, or leverage your existing or customized security models as the adapters, and then "plug" them into JAAS. This should provide a standard-based and highly customized authentication and authorization for your enterprise applications.

More Stories By Guosheng Huang

Guosheng Huang, PhD, is a senior software developer with Wysdom Inc.
He has over 15 years of experience in software engineering and
technical architecture.

Comments (7) View Comments

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


Most Recent Comments
Laurent DUTHEIL 06/07/05 10:57:55 AM EDT

Hello,

I'm very interested about your article.
But the source are not available anymore.
Where can we donload them ?

Thank you.
Laurent.

Jon Lee 02/10/05 09:30:07 PM EST

Dr. Huang,

Thank you writing this informative article.

Contrarily to Maciek Kolesnik and Greg Bishop's opinion, this article is very helpful and useful in understanding JAAS.

The usefulness of understanding JAAS further is now proven when Sun included JAAS in J2SE and J2EE.

Why does this article's helpfulness have anything to do with MS Exchange? So, does it mean only associating with MS Exchange will be helpful? I don't think so.

I think Dr. Huang has already shown that JAAS is easy to extend. So, JAAS can be intergrated with other systems by creating your customized LoginModule.

Peace,
Jon

Nitin Bhavsar 12/08/04 04:54:51 AM EST

1. The article is interesting and nice with simple language. There are plenty of articles on JAAS but still I had many use-case related basic questions. The article helped me understand it (though not fully)...
2. Where are the figures?
3. Where is the listing?
4. The download source took me to the archives page with 100s of links. :(

Thomas Nietsch 07/02/04 05:51:16 AM EDT

Where are the figures?

Greg Bishop 05/10/04 10:27:38 AM EDT

This is not helpful because it does not discuss implementation in an existing security architecture and integration with existing security mechanisms like MS Exchange, etc.

If I wanted to roll my own anything, I sure wouldn''t start with somehting as common as a security architecture.

maciek kolesnik 10/23/03 09:09:05 AM EDT

I think it would really be worthwhile to mention challenges and opportunities that JAAS presents when implementing it in a real J2EE environment (with filters, servlets, EJBs, resource adapters, etc.). There is a talk of adapting JAAS authentication/access control mechanisms in the upcoming J2EE revisions. I'd be interesting in hearing author's opinion on this, otherwise this article probably fits more in the J2SE column :-)

Maciek

Bruce Steely 10/07/03 05:02:10 PM EDT

Where is Listing 1?

@ThingsExpo Stories
"When we talk about cloud without compromise what we're talking about is that when people think about 'I need the flexibility of the cloud' - it's the ability to create applications and run them in a cloud environment that's far more flexible,” explained Matthew Finnie, CTO of Interoute, in this SYS-CON.tv interview at 20th Cloud Expo, held June 6-8, 2017, at the Javits Center in New York City, NY.
The Internet giants are fully embracing AI. All the services they offer to their customers are aimed at drawing a map of the world with the data they get. The AIs from these companies are used to build disruptive approaches that cannot be used by established enterprises, which are threatened by these disruptions. However, most leaders underestimate the effect this will have on their businesses. In his session at 21st Cloud Expo, Rene Buest, Director Market Research & Technology Evangelism at Ara...
The current age of digital transformation means that IT organizations must adapt their toolset to cover all digital experiences, beyond just the end users’. Today’s businesses can no longer focus solely on the digital interactions they manage with employees or customers; they must now contend with non-traditional factors. Whether it's the power of brand to make or break a company, the need to monitor across all locations 24/7, or the ability to proactively resolve issues, companies must adapt to...
The current age of digital transformation means that IT organizations must adapt their toolset to cover all digital experiences, beyond just the end users’. Today’s businesses can no longer focus solely on the digital interactions they manage with employees or customers; they must now contend with non-traditional factors. Whether it's the power of brand to make or break a company, the need to monitor across all locations 24/7, or the ability to proactively resolve issues, companies must adapt to...
Artificial intelligence, machine learning, neural networks. We’re in the midst of a wave of excitement around AI such as hasn’t been seen for a few decades. But those previous periods of inflated expectations led to troughs of disappointment. Will this time be different? Most likely. Applications of AI such as predictive analytics are already decreasing costs and improving reliability of industrial machinery. Furthermore, the funding and research going into AI now comes from a wide range of com...
In this presentation, Striim CTO and founder Steve Wilkes will discuss practical strategies for counteracting fraud and cyberattacks by leveraging real-time streaming analytics. In his session at @ThingsExpo, Steve Wilkes, Founder and Chief Technology Officer at Striim, will provide a detailed look into leveraging streaming data management to correlate events in real time, and identify potential breaches across IoT and non-IoT systems throughout the enterprise. Strategies for processing massive ...
SYS-CON Events announced today that GrapeUp, the leading provider of rapid product development at the speed of business, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Grape Up is a software company, specialized in cloud native application development and professional services related to Cloud Foundry PaaS. With five expert teams that operate in various sectors of the market acr...
Internet of @ThingsExpo, taking place October 31 - November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA, is co-located with 21st Cloud Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The Internet of Things (IoT) is the most profound change in personal and enterprise IT since the creation of the Worldwide Web more than 20 years ago. All major researchers estimate there will be tens of billions devic...
SYS-CON Events announced today that Ayehu will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on October 31 - November 2, 2017 at the Santa Clara Convention Center in Santa Clara California. Ayehu provides IT Process Automation & Orchestration solutions for IT and Security professionals to identify and resolve critical incidents and enable rapid containment, eradication, and recovery from cyber security breaches. Ayehu provides customers greater control over IT infras...
SYS-CON Events announced today that MobiDev, a client-oriented software development company, will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. MobiDev is a software company that develops and delivers turn-key mobile apps, websites, web services, and complex software systems for startups and enterprises. Since 2009 it has grown from a small group of passionate engineers and business...
SYS-CON Events announced today that Cloud Academy named "Bronze Sponsor" of 21st International Cloud Expo which will take place October 31 - November 2, 2017 at the Santa Clara Convention Center in Santa Clara, CA. Cloud Academy is the industry’s most innovative, vendor-neutral cloud technology training platform. Cloud Academy provides continuous learning solutions for individuals and enterprise teams for Amazon Web Services, Microsoft Azure, Google Cloud Platform, and the most popular cloud com...
SYS-CON Events announced today that CA Technologies has been named "Platinum Sponsor" of SYS-CON's 21st International Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. CA Technologies helps customers succeed in a future where every business - from apparel to energy - is being rewritten by software. From planning to development to management to security, CA creates software that fuels transformation for companies in the applic...
We build IoT infrastructure products - when you have to integrate different devices, different systems and cloud you have to build an application to do that but we eliminate the need to build an application. Our products can integrate any device, any system, any cloud regardless of protocol," explained Peter Jung, Chief Product Officer at Pulzze Systems, in this SYS-CON.tv interview at @ThingsExpo, held November 1-3, 2016, at the Santa Clara Convention Center in Santa Clara, CA
SYS-CON Events announced today that IBM has been named “Diamond Sponsor” of SYS-CON's 21st Cloud Expo, which will take place on October 31 through November 2nd 2017 at the Santa Clara Convention Center in Santa Clara, California.
Amazon started as an online bookseller 20 years ago. Since then, it has evolved into a technology juggernaut that has disrupted multiple markets and industries and touches many aspects of our lives. It is a relentless technology and business model innovator driving disruption throughout numerous ecosystems. Amazon’s AWS revenues alone are approaching $16B a year making it one of the largest IT companies in the world. With dominant offerings in Cloud, IoT, eCommerce, Big Data, AI, Digital Assista...
SYS-CON Events announced today that Enzu will exhibit at SYS-CON's 21st Int\ernational Cloud Expo®, which will take place October 31-November 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Enzu’s mission is to be the leading provider of enterprise cloud solutions worldwide. Enzu enables online businesses to use its IT infrastructure to their competitive advantage. By offering a suite of proven hosting and management services, Enzu wants companies to focus on the core of their ...
Multiple data types are pouring into IoT deployments. Data is coming in small packages as well as enormous files and data streams of many sizes. Widespread use of mobile devices adds to the total. In this power panel at @ThingsExpo, moderated by Conference Chair Roger Strukhoff, panelists looked at the tools and environments that are being put to use in IoT deployments, as well as the team skills a modern enterprise IT shop needs to keep things running, get a handle on all this data, and deliver...
In his session at @ThingsExpo, Eric Lachapelle, CEO of the Professional Evaluation and Certification Board (PECB), provided an overview of various initiatives to certify the security of connected devices and future trends in ensuring public trust of IoT. Eric Lachapelle is the Chief Executive Officer of the Professional Evaluation and Certification Board (PECB), an international certification body. His role is to help companies and individuals to achieve professional, accredited and worldwide re...
IoT solutions exploit operational data generated by Internet-connected smart “things” for the purpose of gaining operational insight and producing “better outcomes” (for example, create new business models, eliminate unscheduled maintenance, etc.). The explosive proliferation of IoT solutions will result in an exponential growth in the volume of IoT data, precipitating significant Information Governance issues: who owns the IoT data, what are the rights/duties of IoT solutions adopters towards t...
With the introduction of IoT and Smart Living in every aspect of our lives, one question has become relevant: What are the security implications? To answer this, first we have to look and explore the security models of the technologies that IoT is founded upon. In his session at @ThingsExpo, Nevi Kaja, a Research Engineer at Ford Motor Company, discussed some of the security challenges of the IoT infrastructure and related how these aspects impact Smart Living. The material was delivered interac...