Generate QR code for user check-in.

[andres-valdes]

It would be really useful for potential projects and extensions to the smoothie suite if we could generate a QR code for the user (after they've confirmed their attendance).

Perhaps within the QR code we could encrypt something like:

{
    "id": 42
}

This would indicate their id within the database, this would be useful to mark them as "checked in" on the day of the event.

Perhaps we should blast this QR code with a secret, so user's can't falsify their own QR codes, and can only receive one from us. This could also serve as our tracker for meals, but that sounds like something outside of the scope of mango/peaches.

Perhaps someone should draft a proposal for a project of that nature?

[SCKelemen]

You actually don't need to encrypt it. You could just hash the information, and encrypt the hash. This is how digital signatures work. If you want to have a stateless token, where access to a database is not desirable for whatever reason, you could actually use a pattern like JWTs for handling. JSON Web Tokens (JWT) define a standardized pattern for this kind of thing, and you could encode the entire JWT into the QR code.