# Are decompilers illegal?



## monoman

Is decompiling software illegal? I found a few programs out there, but I'm curious to know whether they are legal or not -  for example would decompiling a copyrighted piece of software, and getting access to the source code be illegal, or is it only illegal to modify the code, and publish it as your own? 

Thanks


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## ADE

sounds illegal to me.


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## Cromewell

They are legal to a point. It depends on where you live andwhat copyright/fair use laws exist there and also on what you do with it.

Don't expect to get nice pretty code back either, generally what you are going to get back is some code that more or less does what the executable file did.


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## monoman

I should have a look at my local laws then I suppose.



> Don't expect to get nice pretty code back either, generally what you are going to get back is some code that more or less does what the executable file did.



So you won't get the exact source code returned?
I'm just gonna have to install the decompiler, and have a good old play around with it I think - In accordance with my local laws of course.


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## Runn3r.cze

i think the decompilers are legal, but it's illegal to decompile some copyrighted software... just my mind


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## ducis

monoman said:


> Is decompiling software illegal? I found a few programs out there, but I'm curious to know whether they are legal or not -  for example would decompiling a copyrighted piece of software, and getting access to the source code be illegal, or is it only illegal to modify the code, and publish it as your own?
> 
> Thanks



I probably depends on what you do with the source code...
I'm sure they wouldn't have a problem with you importing your own 3d models and giving them game functions as long as you don't use it in multiplayer...


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## refresher

monoman said:


> Is decompiling software illegal? I found a few programs out there, but I'm curious to know whether they are legal or not -  for example would *decompiling a copyrighted piece of software*, and getting access to the source code be illegal, or is it only illegal to *modify the code*, and *publish it as your own?*
> 
> Thanks



The bolded part is illegal. Also when you sign the EULA, it usually says no modifications are allowed or reverse engineering.


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## monoman

refresher said:


> The bolded part is illegal. Also when you sign the EULA, it usually says no modifications are allowed or reverse engineering.


Those were my initial suspicions, just curious as to whether the software _itself_ was illegal. I guess decompiling is kind of like certain aspects of torrenting software when it comes to the legitimacy of it - Riddled with loopholes and ambiguity. 

Then again I never read an EULA license in my life, I must admit.


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## Cromewell

> So you won't get the exact source code returned?


Only in a few instances, java bytecodes for example can be decompiled exactly to their source. But most if not all C/C++ decompilers will give you approximate code as it's not really possible to get those back out exactly as they went in





> it usually says no modifications are allowed or reverse engineering.


But most also say except to the point allowed by law or something similar.


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## johnny

Are you talking about using a key gen to generate a product key to use the software?


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## Cleric7x9

johnny said:


> Are you talking about using a key gen to generate a product key to use the software?



lol?


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## Cromewell

> Are you talking about using a key gen to generate a product key to use the software?


No. He's asking about using a program to more or less generate the source code. Most of the time this is done to partially reverse engineer something so that you can offer interoperability with your own software.


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## techdude2007

Decompilers are usually illegal according to the software's EULA or Terms of Agreement. 


> The user shall not transfer, distribute or dissemble in any way, in whole or in part, any of the software (From my companies Terms of Agreement)



Most companies that produce software have a part this is like this in their Agreements or EULA.  The part _*dissemble*_ means decompile.

Usually by having the software on your computer, you are bound to the EULA or the Agreements, just like a legal contract, so by using a decompiler is therefore illegal, because you are violating the legal contract.

The original point of the decompiler was to help the programmer who owned the program to get their source code back, in case they lost the code.


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