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Re: Unsealing a jar file at runtime

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From	lewbloch <lewbloch@gmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: Unsealing a jar file at runtime
Date	Fri, 29 Jul 2011 13:42:31 -0700 (PDT)
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On Jul 28, 4:21 am, Andreas Leitgeb <a...@gamma.logic.tuwien.ac.at>
wrote:
> raph...@gmail.com <raph...@gmail.com> wrote:
> > I don't suppose that this is possible, perhaps with reflection?
> > The idea is for a plugin to extend a class, but the class is not a
> > public class, so can only be extended from within the same package.
> > If the jar file was unsealed, then a class could be created within the
> > plugin that is in the same package, is public and extends the non-
> > public class.
>
> Breaking open a seal is typically easily done.
> Reinstating someone else's seal on the changed
> content is "believed" to be much harder. I also
> believe that it is, but I'm no crypto-expert.

Even were you to succeed in extending the package-private class and
making it public, there are gotchas.  The parent class (the one
already in the JAR) could make assumptions of package-private
visibility that a public subclass would break, e.g., exposure of
package-private methods or attributes for use by its putative friends.

--
Lew

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Thread

Unsealing a jar file at runtime "raphfrk@gmail.com" <raphfrk@gmail.com> - 2011-07-28 02:36 -0700
  Re: Unsealing a jar file at runtime Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-07-28 11:21 +0000
    Re: Unsealing a jar file at runtime lewbloch <lewbloch@gmail.com> - 2011-07-29 13:42 -0700
    Re: Unsealing a jar file at runtime "raphfrk@gmail.com" <raphfrk@gmail.com> - 2011-08-01 14:48 -0700
      Re: Unsealing a jar file at runtime Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-01 21:22 -0400
      Re: Unsealing a jar file at runtime Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-02 13:41 +0000

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