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Qt Charts licensing issue



  • Hi,
    While I'm using Qt Charts in my project and I can't buy the commercial license, I need to publish my software under the GNU GPLv3 license as mentioned here.
    The problem is that I can't release the source code of some encryption methods, which I use to secure the user's data(keyboard activity...). Releasing this code will break the security and breach the user's privacy.
    I gave a look at the Qwt(because it's under LGPL), but Qt Chart is much better in my opinion.
    My questions:

    • Is there any option to use Qt Charts under the LGPL license ?
    • Is it possible to not release some parts of my code under the GPL license ?

    Your help and support is greatly appreciated !


  • Lifetime Qt Champion

    @SamurayH said in Qt Charts licensing issue:

    Releasing this code will break the security and breach the user's privacy.

    Security by obscurity has never worked.

    Is there any option to use Qt Charts under the LGPL license ?

    No.

    Is it possible to not release a some parts of my code under the GPL license ?

    You should discuss this with your laywer, which I'm not.

    Regards



  • Thanks @aha_1980 ,
    I also did like this part : "Security by obscurity has never worked.". But I'm not a expert in cryptography.
    I think I've found something useful here, see the answer of Bruce E. Burdick.



  • Is it legit to compile a program under GPL and a plugin for it under LGPL? To me if you can do that, I would build your encryption methods into a standalone library that your program uses and release that as LGPL and your main program which contains your charts can be GPL and you don't release your encryption methods source code. I've never done this but when I go to the plugin wikipedia page it says a reason to use plugins is:
    "to separate source code from an application because of incompatible software licenses." https://en.wikipedia.org/wiki/Plug-in_(computing)

    Hope it helps.



  • You're right @MrShawn, I missed the plugins trick, thanks so much.
    I will refer more on this topic, and when it's clear I will mark this topic as solved "إن شاء الله".


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