Re: licence key validation method
Re: licence key validation method
- Subject: Re: licence key validation method
- From: Charles Srstka <email@hidden>
- Date: Mon, 12 Jan 2015 20:18:35 -0600
>
> On Jan 12, 2015, at 6:42 PM, João Varela <email@hidden> wrote:
>
> Hi
>
> I rolled out my own license scheme so that I don’t have to pay anyone. ;) I find that coding license checking methods with Cocoa and Objective-C is terribly unsafe. Objective-C has the nasty habit of exposing classes and their methods, which you can easily access/find out if you know what you are doing (otool and class-dump for starters). I do all my license checking code in C++ or just plain C, and use redundant checking in different places. Another trick I learned in a conference is to use critical variables as static variables rather than class ivars. However, my needs are probably different than yours, but all I’m saying be careful how you expose your licensing code if you are going to use objective C.
>
> Please read this:
>
> http://loadcode.blogspot.pt/2006/02/cracking-software-on-os-x.html
>
> and this:
>
> http://lifehacker.com/5736101/how-to-crack-just-about-any-mac-app-and-how-to-prevent-it <http://lifehacker.com/5736101/how-to-crack-just-about-any-mac-app-and-how-to-prevent-it>
I used to worry about stuff like that, and spent a whole bunch of time trying to obfuscate all the licensing code. Now I just put it in plain C/Obj-C functions, because:
1. The assembly is always there. No matter how many precautions you take, it’s always going to be possible to crack your code. It’s just a matter of how much time one chooses to spend cracking it.
2. There’s *always* going to be at least one guy who’s willing to spend enough time to crack it.
3. That one guy will post his crack on a torrent somewhere, and then everyone else will have access to it regardless of their skill level.
Basically, it’s a waste of time. If people want a cracked version of their app, they’ll get a cracked version of your app. Fretting about things like this is just a time sink without much benefit.
Charles
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