Can you add a feature to lock an already existing pdf from file location in flutter?

Hey @binSaed @PcolBP 

I was working on a client project and it is a banking product and they want to add a functionality like add a feature like lock and unlock password feature for it. Using your app I'm able to unlock and view any pdf. 

But can you give a functionality like unlock a pdf and save and lock a pdf and save file in flutter?

Thanks
