Best approach to create a security environment in Java

I need to create a desktop application that will run third party code, and I need to avoid the third party code from export by any way (web, clipboard, file io) informations from the application.

Somethig like:

public class MyClass {

    private String protectedData;

    public void doThirdPartyTask() {
        String unprotedtedData = unprotect(protectedData);
        ThirdPartyClass.doTask(unprotectedData);
    开发者_运维百科}

    private String unprotect(String data) {
        // ...
    }

}

class ThirdPartyClass {

    public static void doTask(String unprotectedData) {
        // Do task using unprotected data.
        // Malicious code may try to externalize the data.
    }


}

I'm reading about SecurityManager and AccessControler, but I'm still not sure what's the best approach to handle this.

What should I read about to do this implementation?

First of all, there is pretty much no way you can stop every information leak on a local computer. You can certainly restrict network access, and even a lot of file system access, but there is nothing that would stop the gui from popping up a dialog showing the information to the user on the screen, or any other 100 ways you could "leak" data.

Secondly, you keep talking about the policy file being changeable by the user. yes, it is. it sounds like you are basically trying to recreate DRM. I'd suggest reading up on DRM and the general futility of it. It essentially boils down to giving someone a locked box and the key to the box and telling them not to open it. If someone has physical access to your program, there is almost nothing you can do to stop them from getting data out of it, in java or pretty much any other programming language (at least, not on computers as they are built today).

A general approach would be to run your jvm with a security policy that grants java.security.AllPermission to your codebase (i.e. jar) and no permissions whatsoever to the third-party codebase. Here is some documentation on how to run with a policy file and what to put in said file.