The characteristics of an application should be considered when deciding the layer and type of security to be provided for applications. The following sections discuss the characteristics of the common mechanisms that can be used to secure Java EE applications. Each of these mechanisms can be used individually or with others to provide protection layers based on the specific needs of your implementation.
Java SE Security Mechanisms
Java SE provides support for a variety of security features and mechanisms:
Java Authentication and Authorization Service (JAAS): JAAS is a set of APIs that enable services to authenticate and enforce access controls upon users. JAAS provides a pluggable and extensible framework for programmatic user authentication and authorization. JAAS is a core Java SE API and is an underlying technology for Java EE security mechanisms.
Java Generic Security Services (Java GSS-API): Java GSS-API is a token-based API used to securely exchange messages between communicating applications. The GSS-API offers application programmers uniform access to security services atop a variety of underlying security mechanisms, including Kerberos.
Java Cryptography Extension (JCE): JCE provides a framework and implementations for encryption, key generation and key agreement, and Message Authentication Code (MAC) algorithms. Support for encryption includes symmetric, asymmetric, block, and stream ciphers. Block ciphers operate on groups of bytes; stream ciphers operate on one byte at a time. The software also supports secure streams and sealed objects.
Java Secure Sockets Extension (JSSE): JSSE provides a framework and an implementation for a Java version of the Secure Sockets Layer (SSL) and Transport Layer Security (TLS) protocols and includes functionality for data encryption, server authentication, message integrity, and optional client authentication to enable secure Internet communications.
Simple Authentication and Security Layer (SASL): SASL is an Internet standard (RFC 2222) that specifies a protocol for authentication and optional establishment of a security layer between client and server applications. SASL defines how authentication data is to be exchanged but does not itself specify the contents of that data. SASL is a framework into which specific authentication mechanisms that specify the contents and semantics of the authentication data can fit.
For more information on Java SE security, visit http://docs.oracle.com/javase/6/docs/technotes/guides/security/.
Java EE Security Mechanisms
Java EE security services are provided by the component container and can be implemented by using declarative or programmatic techniques (see Securing Containers). Java EE security services provide a robust and easily configured security mechanism for authenticating users and authorizing access to application functions and associated data at many different layers. Java EE security services are separate from the security mechanisms of the operating system.
In Java EE, component containers are responsible for providing application-layer security, security services for a specific application type tailored to the needs of the application. At the application layer, application firewalls can be used to enhance application protection by protecting the communication stream and all associated application resources from attacks.
Java EE security is easy to implement and configure and can offer fine-grained access control to application functions and data. However, as is inherent to security applied at the application layer, security properties are not transferable to applications running in other environments and protect data only while it is residing in the application environment. In the context of a traditional enterprise application, this is not necessarily a problem, but when applied to a web services application, in which data often travels across several intermediaries, you would need to use the Java EE security mechanisms along with transport-layer security and message-layer security for a complete security solution.
The advantages of using application-layer security include the following.
Security is uniquely suited to the needs of the application.
Security is fine grained, with application-specific settings.
The disadvantages of using application-layer security include the following.
The application is dependent on security attributes that are not transferable between application types.
Support for multiple protocols makes this type of security vulnerable.
Data is close to or contained within the point of vulnerability.
For more information on providing security at the application layer, see Securing Containers.
Transport-layer security is provided by the transport mechanisms used to transmit information over the wire between clients and providers; thus, transport-layer security relies on secure HTTP transport (HTTPS) using Secure Sockets Layer (SSL). Transport security is a point-to-point security mechanism that can be used for authentication, message integrity, and confidentiality. When running over an SSL-protected session, the server and client can authenticate each other and negotiate an encryption algorithm and cryptographic keys before the application protocol transmits or receives its first byte of data. Security is active from the time the data leaves the client until it arrives at its destination, or vice versa, even across intermediaries. The problem is that the data is not protected once it gets to the destination. One solution is to encrypt the message before sending.
Transport-layer security is performed in a series of phases, as follows.
The client and server agree on an appropriate algorithm.
A key is exchanged using public-key encryption and certificate-based authentication.
A symmetric cipher is used during the information exchange.
Digital certificates are necessary when running HTTPS using SSL. The HTTPS service of most web servers will not run unless a digital certificate has been installed. Digital certificates have already been created for the GlassFish Server.
The advantages of using transport-layer security include the following.
It is relatively simple, well-understood, standard technology.
It applies to both a message body and its attachments.
The disadvantages of using transport-layer security include the following.
It is tightly coupled with the transport-layer protocol.
It represents an all-or-nothing approach to security. This implies that the security mechanism is unaware of message contents, so that you cannot selectively apply security to portions of the message as you can with message-layer security.
Protection is transient. The message is protected only while in transit. Protection is removed automatically by the endpoint when it receives the message.
It is not an end-to-end solution, simply point-to-point.
For more information on transport-layer security, see Establishing a Secure Connection Using SSL.
In message-layer security, security information is contained within the SOAP message and/or SOAP message attachment, which allows security information to travel along with the message or attachment. For example, a portion of the message may be signed by a sender and encrypted for a particular receiver. When sent from the initial sender, the message may pass through intermediate nodes before reaching its intended receiver. In this scenario, the encrypted portions continue to be opaque to any intermediate nodes and can be decrypted only by the intended receiver. For this reason, message-layer security is also sometimes referred to as end-to-end security.
The advantages of message-layer security include the following.
Security stays with the message over all hops and after the message arrives at its destination.
Security can be selectively applied to different portions of a message and, if using XML Web Services Security, to attachments.
Message security can be used with intermediaries over multiple hops.
Message security is independent of the application environment or transport protocol.
The disadvantage of using message-layer security is that it is relatively complex and adds some overhead to processing.
The GlassFish Server supports message security using Metro, a web services stack that uses Web Services Security (WSS) to secure messages. Because this message security is specific to Metro and is not a part of the Java EE platform, this tutorial does not discuss using WSS to secure messages. See the Metro User’s Guide at http://metro.java.net/guide/.