In the JEUS security system, a login is a process that associates a Subject with a Java execution thread. This process is different from authentication, which takes place before the Subject is associated with an execution thread. Therefore, if the authentication is successful, a login will proceed. But if the authentication fails, a login also fails.

After a Subject has logged in successfully, the Subject goes through authorization. The login concept may thus be seen as an umbrella that spans both authentication and authorization. The opposite of a login process is a logout process, which disassociates a Subject from its execution thread.

Note that the implementation of a login process requires a stack-based operation. Several Subjects can be logged in at any time with each new Subject being pushed onto the top of a stack. Only the Subject on top of the stack is used for authorization. When the Subject logs out, the top Subject is removed from the stack, and the next Subject at the top of the stack is activated.

The following illustrates this mechanism.

In the JEUS security system, only one login stack is allowed for each Java thread. As shown in the Security System Architecture figure, the login mechanism is implemented by the jeus.security.impl.login.CommonLoginService interface.

Authentication is a process of obtaining the identity of a caller for the purpose of using it for authorization at a later time.

In the JEUS security system, an identity is represented as a Principal that is defined by the java.security.Principal interface.

A Principal is stored as an attribute value of a Subject, which, as described in the previous section, is implemented by the jeus.security.base.Subject class and associated with an execution thread. A Subject includes Principals and credentials as its security attributes.

The following is a UML diagram for a JEUS Subject.

As shown, the Subject has a main Principal as its unique ID. The Subject may also carry any number of additional optional Principals. These are non-unique Principals that may be shared by several Subjects, and these non-unique Principals are referred to as group group Principals.

Subject can also have public or private credentials. Credentials are usually used as a proof to authenticate the Subject or to deliver specific information. An example of a private credential is a password. An example of a public credential is a digital certificate.

The credentials of a given Subject may be created by using its sub-class, credentialFactory class. The actual credentials are obtained from the credential factories using the refresh() method, and they are added to the public or private credential sets.

In the JEUS security system, authorization is a process of determining whether a previously authenticated Subject should be allowed to perform a particular operation.

Authorization happens at the system level. For example, authorization is required to determine whether a certain Subject, usually an administrator, is authorized to boot or shut down the JEUS server. Authorization is also required at the application level, for example, when a JEUS engine checks whether a remote caller should be allowed to access a particular application component, such as a specific EJB method or a servlet.

As in J2EE, authorization in the JEUS security system is a role-based mechanism. The developer or assembler of a J2EE application sets up security restrictions that are assigned to roles, to which Principals are mapped during the deployment of an application.

In the JEUS security system, authorization mappings are referred to as permissions (sub-classes of java.security.Permission). For example, the Principal "user1" is said to have the permission to access a role called R. That is, user1 belongs to the role group R.

Let's suppose that the role R includes the permission to access the resource JNDI and execute the lookup action.

The following illustrates role-based authorization.

As seen in the previous figure, only Principals and roles are represented as physical entities. The resource circle in the figure has a dashed outline to denote that resources are implied and not physically modeled in the authorization process.

In the previous figure, the two boxes marked RolePermission and ResourcePermission represent instances of the two classes jeus.security.resource.RolePermission and jeus.security.resource.ResourcePermission, respectively. Both of these classes extend the basic java.security.Permission abstract class, and there are various other sub-classes of the Permission class.

Briefly summarized, a Principal owns a set of permissions and those permissions grant the Principal a set of logical roles. These roles in turn own another set of permissions that grant those roles access to a set of actions on the resources. By following these indirect mappings, one can determine whether a principal should be allowed to perform a specific action on a resource.

The figure above shows that the Principal user1 owns a RolePermission. The arrows marked "owns" in the figure intuitively denote a direct, static binding. However, the term "implies" used to show that the RolePermission implies role R is different. This implication indicates that binding is not static. Rather, the relationship between the RolePermission and the role R is determined dynamically at runtime by invoking the method implies(Permission p) on then RolePermission instance.

If the implies() method returns true, the RolePermission is said to imply role R, otherwise it is not. Thus, in the former case, principal user1 is granted the role R, and in the latter case it is not. The same logic applies for the implication between the role R and the Resource JNDI.

Given the previous information, it is not difficult to implement dynamic mappings. If we just change the implementation of the implies() method, we can make a permission imply a role or resource under certain conditions. For example, we might want to create a dynamic mapping between principal user1 and role R, so that user1 is granted with role R during the business hours (9 AM to 5 PM). To do this, we could simply create a new RolePermission sub-class, called TimeConstrainedRolePermisson, and override the implementation of the implies() method. In this method, you can add a check for the additional time-constraint.

For more examples of implementing dynamic mappings, refer to [Figure 1.5] and [Figure 1.6].

As shown in [Figure 1.5], principal user1 is not granted role R.

As shown in the previous figures, the TimeConstrainedRolePermission class contains two variables, Name and Actions. Name is set to the name of the implied role, which is R in the example, and the Actions are set to the time when the implication is valid, which is between 9 AM and 5 PM in the example. Both Name and Actions are standard variables that are declared in most java.security.Permission class implementations.

Moreover, apart from the basic Permission-based mappings, every permission in the authorization system belongs to one of the following three types.

In the JEUS security system, all permission mappings are the classes that implement the jeus.security.base.PermissionMap class. These PermissionMap classes are included in the jeus.security.base.Policy class.

Policy class has two kinds of PermissionMaps.

Each PermissionMap contains the three aforementioned permission types--excluded, unchecked and checked permissions. In the case of checked permissions, a permission and role PermissionMap are combined through a Principal or role. A Policy and resource PermissionMap are combined through a context ID, which indicates the authorization scope.

The following is a UML diagram of Policy and PermissionMap classes.

The following figure summarizes information about mappings. .

In the previous figure, we have a Policy instance that contains one principal-to-role mapping, which is required, and also two role-to-resource mappings with context IDs A and B, respectively. All three PermissionMaps contain three sets of permissions as follows.

The oval figures inside the boxes represent the actual permission instances (Name: Action) with Name and Action variables.

Let's suppose that a Subject, with context ID "A" and the Principal "user1", wants to access JNDI to modify it.

This authorization query would be processed by the authorization system as follows:

In this process, although user1 is mapped to the role Administrator, since Administrator is also in the excluded set, user1 is not granted the role Administrator. This is because excluded permissions have higher precedence over both unchecked and checked permissions.

Using the previous figure and following the step-by-step instructions above, you can work out the following authorization queries.

Security auditing generally involves capturing security-related events such as failed authentication and runtime exceptions and evaluating these events for better system security.

The JEUS security system features a simple yet flexible auditing mechanism using security events. Whenever something significant happens in the system, such as failed authentication or failed authorization, an event will be posted to a set of registered event handlers.

The handler implementations, which can be fully customized, responds with an appropriate action, such as locking a Subject's credential when authentication has failed too many times in a row.

Each class in the security system that implements security functionalities constitutes as a Service. A Service is simply an implementation of an Service Provider Interface (SPI) that provides some security functionality, whether it is authentication, authorization, or networking.

SPI is an abstract class of the Java package jeus.security.spi. These SPI class should be extended and implemented in order to implement customized security functionality. The extended sub-classes of an SPI class are called Services.

All instances of Services in the security system are treated individually as independent entities whose services are called as needed. However, it is common for a Service implementation to make calls to another SPI, and some dependency may exist among different Services. In order to initialize Services. All Services receives a key–value pair property value used to initialize the Service. The configuration data of a Service can also be saved in a configuration file.

All Services may also optionally define a JMX bean that will be exported to the JEUS management system. The JMX MBean is normally created based on a MBeanInfo instance returned by the Service.getMBeanInfo() method.

All Services have two states, a created state and a destroyed state. The create() and destroy() methods are called to transition between the two states. Calling these methods will invoke doCreate() and doDestroy() abstract methods. These abstract methods should be implemented by Service sub-classes for service initialization and management.

Security domain is a collection of security Service instances. Several domains may exist concurrently within the security system. The purpose of a domain is to allow deployed applications and JEUS sub-systems to use individual security Services. A domain separates the security Services for each application.

For example, the JEUS server could be set up to use a special domain. In this case, it is call the SYSTEM_DOMAIN. This domain contains Subjects and Policies that are used to manage the JEUS server. For example, the SYSTEM_DOMAIN contains the user information for a main Subject called administrator, which can be used to boot or shut down the server.

Another domain, let's call it APP_DOMAIN, could be used by a deployed J2EE application. That domain might also contain a user information for a Subject called administrator, which is different from the JEUS server administrator. You could also configure a different repository mechanism for each domain. While the SYSTEM_DOMAIN can be configured to use a simple XML file to store Subject information, the APP_DOMAIN can be configured to use a remote database to read and write Subject information.

The domain concept is illustrated in the following figure.

Use of the domain feature is optional. If no domain is specified, a special SYSTEM_DOMAIN is used.

By default, JEUS uses two domains, SYSTEM_DOMAIN and SHARED_DOMAIN, as follows:

To apply different security services to applications, create a separate domain and configure the domain.xml file. For more information about creating and configuring security domains, refer to "Chapter 2. Configuring the Security System".

This chapter explains how to minimize the performance impact that the security system has on the overall performance of the JEUS server.

The following are measures for improving performance of the overall security system.

This section explains how to improve the security system level despite a performance hit.

The following are the ways to improve the overall security level of JEUS: