When software comes with a license code, e.g. HXD5S-LB99C-HII54 how does the program know the code is valid without internet validation? For example, some older Microsoft software like Office 2003 could be installed without internet access and you would type in the code and the computer would validate the code. I’ve always been curious about this and the mechanism of how validation occurs.
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Depends on the software, but usually there’s a pattern that has to be matched to validate the code… this is baked into the software itself. So if you step through it with a debugger and have lots of patience, you can figure out what the code generating algorithm is and generate your own valid codes.
Most modern registration numbers are hashed against your computer’s UUID and hardware configuration, so you need to find the correct code for your particular system.
I am sure someone will chime in with a better example..
The code to validate the license is more than likely part of the same code that generates the license. So the code takes 0 or more inputs and creates a “hash” of that output – this then becomes the license code.
The software can take that “hash” and the same 0 or more inputs to validate that hash was correct. That way the software does not need an internet connection.
Also, because the code to validate the hash is embedded in the software, incredible coders can reverse engineer that code and use it to create a keygen to create keys for the same software.
I have tried to keep this simple and I hope it makes sense?
The mathematical equation that was used to generate the code, is the reverse of what the application is looking for.
So when it breaks down the code using the reverse of the original equation it gets the hash it wants, if the code is valid.
These vids might help:
Unless your question is weather or not your can reuse your license.
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