use Perl

• been there, done that (Score:2)

  by jmm (276)

  I wrote the initial set of code that Larry turned into the CRYPTSWITCH enabled encryption filter in early perl3. Carrying forward that ability for encrypting scripts was the initial purpose of the Filter module in perl5, although the ability to apply arbitrary filtering to the incoming code stream was designed into it and the Filter::Crypt module was one of the initial examples of how to use that ability.

  But, the company I was at was never foolish enough to believe that encrypting scripts made the code saf
  • I, haX0r (Score:2)

    by schwern (1528)

    I recall scaring the hell out of a programmer that was relying on Filter::decrypt. He'd thought it was full on encryption rather than just elaborate obfuscation and apparently the company had bought into that, too. I told him I could bust the obfuscation. He didn't believe me so he sent me a simple sample. IIRC my algorithm was something like...
    
    require the code
    walk the symbol table looking for globals and subroutines
    Data::Dumper the globals
    B::Deparse the subroutines
    
    The tricky part was the file-scoped
    • Re:I, haX0r (Score:2)

      by jmm (276)

      I haven't tried it, but what I figured the easiest method (even before B::Deparse came along) would be to write another filter and name it Filter::Decrypt. It would use the "real" Filter::Decrypt but tee the results before passing them on as its "filtered" output. It's the basic man-in-the-middle attack.
      • Re:I, haX0r (Score:2)

        by schwern (1528) on 2005.04.13 14:49 (#39659) Homepage Journal

        Wow, I never would have thought of that!

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