If I create a binary that contains exactly the same class-, method- and field signatures as a proprietary application, but I've left everything else out - does the license of the original app still apply?

  • 3
    How did you create this stripped-down version?
    – MadHatter
    Oct 18, 2019 at 21:07
  • 1
    In my case - a tool called "cil-strip". It's part of Mono: github.com/mono/mono/tree/master/mcs/tools/cil-strip But does it matter how the stripped binary is obtained?
    – krafs
    Oct 19, 2019 at 16:03
  • 1
    If this is about a proprietary license or application, it is not really on-topic for Open Source StackExchange. Basically you need to read the license agreement for what you are allowed to do. Normally proprietary licenses say you are not allowed to modify them at all in any way.
    – Brandin
    Oct 20, 2019 at 12:28

1 Answer 1


If you take a software binary B, distributed under licence L, and use a piece of software to modify that binary according to certain pre-defined rules, you have created a modified binary B', which is very likely a derivative work of B in copyright terms. The licence on B' will therefore depend on the terms of L.

If L was a permissive free software licence, then although there may be certain labelling requirements for B', it may also be possible to distribute B' under other licence terms, including copyleft and proprietary ones.

If L was a copyleft free software licence, it will likely require that B' also be licensed under the terms of L (see, eg, GPLv3 ss 6 and 5c, and GPLv2 ss 3 and 2b).

If L was a proprietary licence, you likely have no right to do what you've done and are already in violation; see as a random example this proprietary licence, which says

You shall not alter, disassemble, decompile, reverse-engineer, adapt, translate or modify the Software or any portion thereof ... You shall not copy the Software.

I asked at the top how you created this stripped-down derivative work, and you asked whether it mattered. The short answer is that I'm not a programmer, and in any case there are more things in heaven and earth than are dreamed of in my philosophy; so instead of guessing what you'd done and basing my answer on a guess, it seemed simplest to ask for more detail.

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