Unless they could read my mind it would be extremely easy.
Numerous thoughts I’ve never shared with anyone. Along with witnessing events no one else ever saw and I never talked about. On top of that I could think of new things that only myself would understand if the need arose.
I think most of us have remembered dreams, or certain instances of conversations or events that stuck with us for ages and ages, but that wouldn’t seem important when viewed from the outside.
Hey younger me, here’s an event that you vividly remember from your childhood that nobody would ever think twice about… the “frog incident” from summer camp.
Rather than “remember eating those mulberries from the tree next to the driveway?” it’s “do you remember what you were thinking when eating mulberries back home? It’s that the berries would give you the energy needed to walk up the hill to Grandma’s house”
I agree, as far as this goes. What makes it more interesting is, could the spies send an equally compelling message?
For example: I, too, go to the idea of sending a synopsis of one or more particularly vivid dreams that I had and never told anyone about. But I remember the dreams better than I remember whether I told anyone about them.
Were I running the spy organization, I’d look for one-off conversations from decades ago where my victim told someone about a dream, and then didn’t tell anyone else. Then my message would be something like, “I never told anyone about the time I dreamt about dolphins who were biting the heads off of swimmers; only I know about this dream. Trust that this message is from me.”
Is it possible that the secret organization could trick you into thinking you hadn’t told anyone about something, and use that to establish their bona fides?
Yes. I would have little trouble convincing me I am me. Convincing you I am me may depend on the you.
On thinking about it some more, it’s actually fairly easy, because the shadowy organization knows too much to be convincing.
For instance: Over the course of my schooling, I must have written hundreds of creative writing pieces. The shadowy organization, of course, remembers all of them. But the thing is, I don’t. If they say to past-me “Remember that time in school you had to write a poem about a fish?”, past-me would say “No, actually, I don’t”. Out of all of those hundreds of creative writing assignments, I only remember a couple (not counting the super-obvious ones, like the essay that won me a prize in a contest, or the poem that got published in the high school lit mag).
Or, when I was a kid, my mom took my sister and I to day camps at the local art museum. Every Saturday of my childhood, I created some piece of art. To the best of my knowledge, two of them survive (those are too obvious), and I remember maybe three more of them. The Shadowy Folks could describe all of them, but can’t tell which three of them I remember.
And this is how A.I. is going to get us all!
I haven’t read all the responses but I would rely on memorable events whose details I know I forgot more than ten years ago. For example, imagine you know that you know you forgot more than ten years ago the name of the first girl you ever kissed or the make and model of car you first had sex in. The panopticon would know those details but only you might have an idea when you forgot them.
However, I would still probably be doomed because I am too cynical to believe in messages from the future in any event. Getting two would just make me wonder what present technology allowed them to be so convincing and what they have to gain by convincing me.
Another tactic:
If my past self knows that one message will be from an all-but-omniscient organization that knows all the details of my life and one message will be from future me… what if one of the messages is totally wrong? Just nothing but absurd ramblings, half-remembered nonsense, and outright fabrications?
That one has to be the real message.
Not willingly. But the future you might be tricked or tortured into revealing it. Are you willing to suffer or even die to keep that secret?
One day while I was walking from the train to my office back in the 90s I thought of something which I considered might make an interesting premise, or at least a character background, for a story. I never wrote it down, or told anyone about it. In fact, until reading this thread I hadn’t even thought about it for years. But if I were to mention it to myself in a message I would recognize it as something I had once thought.
One morning at the very beginning of the Covid pandemic, me and my ex were making love and I saw something puzzling that, due to the position we were in, she could not see. I didn’t tell her because… well, use your imagination. I’m the only one who knows about it. However I realize your Evil Organization’s cameras will have recorded it too.
But I thought of writing about on a forum I used to belong to. There’s no way the Evil Organization can know the humourous title I’d have given to that post.
My friend’s dad had a particular ham radio handle that he put on his license plate. I’ve used it for passwords. I never told anybody.
This was not a difficult challenge. If you want to try something really difficult figure out how to could convince yourself that you’re not you.
Okay, an important question. Do I remember when, ten years ago, I got a message from future-self? If so, when the message showed up in 2013, I distinctly remember, before opening it, thinking of a series of words that would appear only in the real message. I opened the two messages and saw that series of words in exactly one of the messages, at which point I knew which was the real message. And today, I’m going to include that series in the real message.
As a corollary, we must assume that the Spymasters’ surveillance failed at the moment in 2013 when I opened the messages, and at the moment in 2023 when I composed my message. Otherwise, both messages would surely include the same content.
I think this is the most interesting part of the question. Even with access to all the stuff in the hypothetical, 1,000 characters imposes some significant limits, about one page from a typical novel (closer to about 3/4 of a page, but I rounded up 
). There’s no point in using mundane stuff. I don’t remember what I had for breakfast on 9/12/2013, and obviously the 2013 me will know that I wouldn’t remember something like that. But then one can get into tricks like saying “you had roasted asparagus with pomegranate juice for breakfast today.” I know I’ve never had anything bizarre like that for breakfast, so all 3 of us would know that was a lie. But would the 2013 me think “only the real me from 2023 would make up a lie like that, because why would some all knowing X-files styles conspirators make up something like that?” Of course that would mean the people making the fake message would have an incentive to use outlandish lies based on the same logic. On the other hand, I could make things obvious, like "the most important day of your life was x/xx/xxxx (my wedding anniversary) based on the idea that the 2013 me would think “some all knowing villains wouldn’t bother to state some obvious and easily verified fact like that, for fear of seeming too obvious.” It might even be a good idea to just say “this is the real you, you need to know this” and then fill up the rest of the message with random letters, because again, what evil organization is going to spend billions or even trillions of dollars just to type up a bunch of random gibberish?
There’s all kinds of other mind games one could play. It makes me think of that scene from The Princess Bride where Vizzini is trying to decide which cup of wine to drink.
There is a movie with Jon Favreau and maybe Vince Vaughn (not important enough to my point to search which movie) where they talk about a person’s sexual highlight reel. It is the memories and/or fantasies one thinks about when self pleasuring when you are not consuming any pornographic material, such as while in the shower.
If the message describes my highlight reel, I would be convinced.
I agree. I can pick specific memories, even ones involving public events, just because I remember those and not others. It’s not obvious why some of them stick in my head vs. not. I have only a small number of memories from preschool, but the ones I do have are highly specific. Even if every person from the school was interviewed, and the whole place somehow covered in cameras, you’d get nowhere.
In any case, I think I could do it in <100 chars, let alone 1000. I have… not exactly synesthesia, but some odd associations between words and mental imagery. I could just describe one of those connections.
I suspect I’d find a short message more believable than a long one. The long one would feel too much like a shotgun approach.
There is a fact about myself that I have never told anyone else and there is no way anyone could have deduced it since it never affected my behavior, so yes I could.
I think it’s time you tell us what it is. You’ll feel better when you do. We’re listening.