I will have a question for you, dear forum residents. I have a .jar file encrypted with ZKM which I think will work for me. I don't know how to decrypt this, can you help me?

  • ZKM (Zelix KlassMaster) by default obfuscates code, not encrypts it (exception: strings). Therefore there is no decryption. The names that have been obfuscated are gone unless ZKM forgot some identifier which can be used to reconstruct the original class name (but I don't think that the ZKM authors made such a mistake).
    – Robert
    Aug 5 '20 at 11:08
  • So we can't remove it from this software?
    Aug 6 '20 at 7:46
  • 1
    I’m voting to close this question because not related to reverse-engineering. Aug 7 '20 at 22:56
  • I also vote to close this question. In case the OP wanted to know how to decompile the JAR file, I suggest benf.org/other/cfr with obfuscation mapping files.
    – Moreaki
    Aug 11 '20 at 23:38
  • I don't agree with closing the issue. OP made a grammatical mistake, using "decrypt" instead of "deobfuscate". There clearly exist solutions for this sort of problem and I don't see how this could possibly be justified for closure under the premise of "not related to reverse-engineering" aside from the lack of awareness of the subject matter.
    – Col-E
    Aug 18 '20 at 17:43

There are a few open source tools that make removing obfuscation patterns quite easy. Some have explicit support for ZKM. Here are are the two popular ones:

And here is one specifically for android:

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