So you're going to rely on the data-collectors' memories to enter and re-enter the salt reliably hundreds or thousands of times (without reminders on yellow stickies "hidden" somewhere accessible)?
And the salt will also be long enough to make deducing it from data available on the laptop(s) difficult enough that it will pass muster with your (hypothetical?) non-naive, non-ignorant ethics committee?
Do you see any conflict among these notions?
Was it the Red Queen or a Philadelphia comedian who "practice(d) believing two mutually contradictory notions before breakfast every day?" Neither? Well, how about Orwell's "doublethink?"