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Decompilers

By ravisunny2
Jan 27, 2007
  1. I have never used a decompiler, but have heard people boasting of their exploits using decompilers.

    Imagine writing a smart s/w that has taken the better part of a year, compiling it, selling/distributing it, and then.. some person devoid of all scruples, simply decompiles your exe, does minor alterations, and begins to sell it.

    It sent tingles up my spine, when I first heard of decompilers.

    Once to prevent a program from being modified (easily), after debugging & testing it, I made global changes in the variable names.

    The variables (with due care), were renamed to dum1, dum2, ...

    That seemed to stop the sneaks right in their tracks.

    Any good ideas how to protect our programs ?
     
  2. jobeard

    jobeard TS Ambassador Posts: 9,348   +622

    1) never ship Scripts (in any language)
    2) consider OBVISCATION
    3) strip all symbols
    4) consider encryption of the binary (hi cost at startup time)
    5) consider a license key validation to your hosted service
     
  3. ravisunny2

    ravisunny2 TS Ambassador Topic Starter Posts: 1,980   +11

    Thanks Jobeard.

    I guess I have used OBVISCATION in a pimitive manner.

    How safe are the OBVISCATION tools ?

    As far as I know, keys, locks (software or hardware), are quite easily broken.
     
  4. Nodsu

    Nodsu TS Rookie Posts: 5,837   +6

    Really, unless you are decompiling Java or PCODE, the people who can make sense of a stripped executable are very rare and modifying such a program to any greater extent is an enormous task.

    Java can be decompiled to almost the original Java source and so can the .NET intermediate binaries. So don't use silly Microsoft technologies or Java :) When compiling to native code, make sure you don't put any debugging information in the executables that you ship to users.

    And nothing you do can really save you from a dedicated cracker - when you run a program, the code has to make it to the RAM and the CPU and therefore this code can be intercepted and analyzed. It's only a matter of time and skill (and possible reward).

    Also, any person taking your program, modifying and then selling it is breaking the law and you can sue their *** of no problem.
     
  5. jobeard

    jobeard TS Ambassador Posts: 9,348   +622

    it's a point of view -- the disassembler will still produce code that can
    be recompiled and executed correctly (if it's worth using at all), BUT the code
    created is nye unto impossile to read, modify and/or reengineer (which is the usual intent).
     
  6. ravisunny2

    ravisunny2 TS Ambassador Topic Starter Posts: 1,980   +11

    Thanks both Nodsu & Jobeard.

    Perhaps I stand corrected regarding breaking of keys & locks.

    In the DOS days, it wasn't uncommon to modify the exe file of Wordstar (not with the intent of selling/distribution).

    Stripped code ?

    Is STAAD or Autocad stripped ?

    These softwares were cracked.

    By the way, can you suggest a decent wp for nondocument code ?

    I have used various wordprocessors on mainframes & PCs.

    On PCs I found Wordstar to be convenient.

    When I leave the DOS platform (which I still have in Win 98), what options do I have ?
     
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