As wikipedia says,

A major limitation on copyright on ideas is that copyright protects only the original expression of ideas

Suppose there are two companies: A and B, that produce software. Now, suppose that A published some commercial program, but obfuscated it, so that its functionality is unchanged, but the machine code produced looks completely different than in unobfuscated one. Subsequently, company B bought this program, deobfuscated its code and started selling it.

As I understand, the original way of expressing ideas by company A was by publishing obfuscated code (the original version was not published at all). Since after deobfuscation by company B, code looks completely different, does it qualify as another way of expressing the same ideas and is legal, or has company B broken the copyright law?

The above question concerns the case when B is selling the original program code that was extracted from published obfuscated version. But imagine that B transformed the code published by A to a completely different form different from both original and obfuscated one, but preserving functionality and sells it. Has company B broken the copyright law in this case?

2 Answers 2


Company B has created a derived work from company A's copyright-protected work, so yes, B has infringed on A's copyright. It might be difficult for A to prove it, however, so B might get away with it, but it's still infringement.

On the other hand, if B creates software that behaves like A's through reverse engineering, that is, by examining the program's function without examining its code, then they will not have infringed the copyright in the code.

  • 2
    Hi! OP posted this question here following my suggestion at the RE.SE chat. I'm curious to why you described "reverse engineering" as "examining the program's function without examining its code". Reverse engineering often involves reviewing the machine code that compose a program. Could you elaborate on this?
    – NirIzr
    Commented May 27, 2019 at 9:07

Obfuscated, just means organized in a confusing way pretty much. That would mean they are using the same code, but just organized in a different way.

That is not expressing it in a different way, its stealing the code and making it look a little different. You wouldn't be guilty of copyright violations, you would be guilty of theft.

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    Yes, it would be a copyright infringement. Theft of what? IP? De-obfuscating would likely be considered a 'derivative work' which is likely a copyright violation.
    – mark b
    Commented May 21, 2019 at 18:55
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    I know what obfuscation means. Using any mechanical or automated means to change the original copyrighted work would be a derivative work. I've been writing software since 1975.
    – mark b
    Commented May 21, 2019 at 18:59
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    I don't understand. Having copyrighted work does not equal stealing it. Source code is frequently copyrighted and then distributed. If that happens, it's still copyrighted. Making a derivative work of the copyrighted material you have in your possession is still an infringement. But it's not necessarily theft. in addition, Copyrighting something (and filing a Form TX) supplies a portion of the copyrighted material.
    – mark b
    Commented May 21, 2019 at 19:18
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    Selling is not a component that is required for there to be copyright infringement. In cases where the material is given away, the damages could be more.
    – mark b
    Commented May 21, 2019 at 22:21
  • 2
    To speak of copyright infringement as "theft" or "stealing" is a metaphor, and is often misleading. It is not technically theft. Mark is correct that infringement does not require selling anything. Commented May 22, 2019 at 3:09

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