Self-verification

This isn’t a trick ques­tion, nor do I have a par­tic­u­lar an­swer in mind.

To­mor­row, all of your mem­o­ries are go­ing to be wiped. There is a cru­cial piece of in­for­ma­tion that you need to make sure you re­mem­ber, and more speci­fi­cally, you need to be very con­fi­dent you were the one that sent this mes­sage and not a third party pre­tend­ing to be you.

How do you go about trans­mit­ting, “sign­ing”, and ver­ify­ing such a mes­sage*?

--edit: I should have clar­ified that one of the as­sump­tions is that some mal­i­cious third party can/​will be at­tempt­ing to send you false in­for­ma­tion from “your­self” and you need to dis­t­in­guish be­tween that and what’s re­ally you.

--edit2: this may be for­mally im­pos­si­ble, I don’t ac­tu­ally know. If any­one can demon­strate this I’d be very ap­pre­ci­a­tive.

--edit3: I don’t have a par­tic­u­lar uni­ver­sal defi­ni­tion for the term “mem­ory wipe” in mind, mainly be­cause I didn’t want to pi­geon­hole the dis­cus­sion. I think this pretty closely mimics re­al­ity. So I think it’s to­tally fine to say, “If you re­tain this type of mem­ory, then I’d do X.”