"I can only show you the door, you have to walk through it". The QR Code is the door, you have to open it, then step through.
Since the code is just an encoding of data or a web url, it cannot execute anything on its own. The app you use may have flaws in it that could allow a buffer overflow or the like though.
As to using it for vaccines, I've not probed anything like this yet. How I would program it would be my app uses encryption to encode personal information (name, dob, amountofjabs). I would then create the QR code from that. The counterapp would then read that code, decode it, and show the person how many jabs. I would hack this by either modifying the app to have a bogus amountofjabs before it goes to the qrcode creation as that would be the easiest point. If someone extracts the encryption method, they can just create their own qrcode, however encoding personal identification in prevents you from using someone else's code. I wouldn't be surprised if they rushed this and made it easier than the above though.
"I can only show you the door, you have to walk through it". The QR Code is the door, you have to open it, then step through.
Since the code is just an encoding of data or a web url, it cannot execute anything on its own. The app you use may have flaws in it that could allow a buffer overflow or the like though.
As to using it for vaccines, I've not probed anything like this yet. How I would program it would be my app uses encryption to encode personal information (name, dob, amountofjabs). I would then create the QR code from that. The counterapp would then read that code, decode it, and show the person how many jabs. I would hack this by either modifying the app to have a bogus amountofjabs before it goes to the qrcode creation as that would be the easiest point. If someone extracts the encryption method, they can just create their own qrcode, however encoding personal identification in prevents you from using someone else's code. I wouldn't be surprised if they rushed this and made it easier than the above though.
I am constantly amazed at the level of sophistication and knowledge of my fellow Pedes. Thank you!