A user data constraint (<TutorialUser-data-constraint> in the deployment descriptor) contains the <transport-guarantee> element. A user data constraint can be used to require that a protected transport layer connection such as HTTPS (HTTP over SSL) be used for all constrained URL patterns and HTTP methods specified in the security constraint. The choices for transport guarantee include CONFIDENTIAL, INTEGRAL, or NONE. If you specify CONFIDENTIAL or INTEGRAL as a security constraint, it generally means that the use of SSL is required, and that type of security constraint applies to all requests that match the URL patterns in the web resource collection and not just to the login dialog box.
The strength of the required protection is defined by the value of the transport guarantee. Specify CONFIDENTIAL when the application requires that data be transmitted so as to prevent other entities from observing the contents of the transmission. Specify INTEGRAL when the application requires that the data be sent between client and server in such a way that it cannot be changed in transit. Specify NONE to indicate that the container must accept the constrained requests on any connection, including an unprotected one.
The user data constraint is handy to use in conjunction with basic and form-based user authentication. When the login authentication method is set to BASIC or FORM, passwords are not protected, meaning that passwords sent between a client and a server on an unprotected session can be viewed and intercepted by third parties. Using a user data constraint with the user authentication mechanism can alleviate this concern. Configuring a user authentication mechanism is described in Specifying an Authentication Mechanism.
To guarantee that data is transported over a secure connection, ensure that SSL support is configured for your server. If your server is the Sun Java System Enterprise Server, SSL support is already configured. If you are using another server, consult the documentation for that server for information on setting up SSL support. More information on configuring SSL support on the Enterprise Server can be found in Establishing a Secure Connection Using SSL and in the Sun GlassFish Enterprise Server v3 Administration Guide.
Good Security Practice: If you are using sessions, after you switch to SSL you should never accept any further requests for that session that are non-SSL. For example, a shopping site might not use SSL until the checkout page, and then it might switch to using SSL to accept your card number. After switching to SSL, you should stop listening to non-SSL requests for this session. The reason for this practice is that the session ID itself was not encrypted on the earlier communications. This is not so bad when you’re only doing your shopping, but after the credit card information is stored in the session, you don’t want a bad guy trying to fake the purchase transaction against your credit card. This practice could be easily implemented using a filter.