The file formats MPQ and CASC are two container formats developed by Blizzard in 1996 and 2014 respectively. Both formats are proprietary and there's no official specification. If these formats are reverse engineered for release of a software library for reading/writing such files, will it infringe on Blizzard rights?

  • 2
    Does Blizzard's EULA or license for the file formats forbid reverse engineering? Commented May 12, 2022 at 20:43
  • I don't know. I found a software library called libmpq for reading and writing of MPQ files, and another called CascLib for CASC files. Both have public source code.
    – user44968
    Commented May 12, 2022 at 20:44
  • 1
    law.stackexchange.com/questions/8277/… Commented May 12, 2022 at 20:45
  • Are you planning on using blackbox or whitebox reverse engineering?
    – forest
    Commented May 13, 2022 at 1:55

1 Answer 1


In Germany (and similarly in the entire EU since Germany implements EU directives in this case), Reverse Engineering is legal IFF

  1. the thing you are Reverse Engineering is publicly available OR
  2. you are legally in possession of the thing (note, you do not!!! need to own it, only possess it) you are reverse engineering.

It is however possible to contractually restrict this, e.g. if you give a test exemplar to your customers, they are legally in the possession of the exemplar, but you can contractually prevent them from reverse engineering it, as a condition of you providing them the exemplar.

Note that this right to reverse engineer only applies to trade secrets – patent protections or other IP protections are unaffected.

This was introduced in 2019 as part of the Gesetz zum Schutz von Geschäftsgeheimnissen, specifically §3,I,2. The GeschGehG implements EU directive 2016/943.

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