If you don't want them to know what it is, encrypt it. Even if they store it, it's not much use. If you don't want them to keep it, find a way to invalidate it

If you don't want them to know what it is, encrypt it. Even if they store it, it's not much use. If you don't want them to keep it, find a way to invalidate it. (This would be for where the read key is time sensitive.. not sure how to make that work)