If the scanner application is looking for very specific data fields to be encoded in the QR code (which I'm 100% positive it is), then I would suspect your plan is all for not. Your encoded message will not match what the app is looking for and will likely just be rejected for not matching the intended data structure. It will not show up as readable text to the scanner app since it isn't able to take you text as input. Sorry, but as a software developer of over 30 years, this is just the honest truth. Now if you have some valid QR codes you can work with, you can determine what data is being used by the app and hijack those inputs to improve your chances of having them see your message. By decoding the contents and determining where your message needs to be included, you could get a valid scan that may display your message. Again, as a programmer, there's also the possibility that they will never see your message even if you get a valid scan because the app may not have a need to display the decoded information. If it is a simple pass/fail check, your plan is all for not. They will only see either a pass for a good scan and decode or a fail for one that doesn't decode properly. You won't know what the results will be unless you actually get the app to do the scanning.