I would probably believe something signed with my own PGP key enough to thoroughly investigate it. If I found something packaged with a blood sample I probably would not be willing to pay to check the sample, because I'm a minor and the costs of testing a DNA sample are something like a year of income for me. Since I wouldn't verify the sample I would probably take the message about as seriously as I'd take anything else in my own handwriting with my signature, which is to say I'd put in several hours of effort but not much more unless I found confirming evidence. If I found a video of myself saying things, accompanied by a PGP sig and a PGP-signed transcript, which did not include any subtle signals of coercion that I could have potentially sent, I'd be very confident.


by Nanashi 1 min read19th Apr 201543 comments


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."