Java Security, 2nd Edition

The Java Sandbox

When Java security is discussed, the discussion typically centers around Java’s applet-based security model -- the security model that is embodied by Java-enabled browsers. It’s considered “applet-based” because in early versions of Java, it applied only to applets that run within a Java-enabled browser. In the Java 2 platform, however, this security model can apply to any Java application as well as to the Java Plug-in, which allows newer browsers to run Java 2 applets. The Java 2 security model is also configurable by an end user or system administrator so that it can be made less restrictive than earlier implementations of that model.

This security model centers around the idea of a sandbox. The idea is when you allow a program to be hosted on your computer, you want to provide an environment where the program can play (i.e., run), but you want to confine the program’s play area in certain bounds. You may decide to give the program certain toys to play with (i.e., you may decide to let it have access to certain system resources), but in general, make sure that the program is confined to its sandbox.

This analogy works better when you consider it from the view of a close relative rather than from the view of a parent. If you’re a parent, you probably consider the purpose of a sandbox to be to provide a safe environment for your child to play in. When my niece Rachel visits me, however, I consider the purpose of a sandbox not (only) to be to protect her, but ...