How can an average person prepare himself to verify his future time-traveler self's identity?
I'm just an average person. I'm not a millionaire with thousands of dollars to spare. I don't have any kind of special power. I'm not currently affiliated with anyone working on anything grand. I'm just a 20 years old college student trying to get through life. However, for one reason or another, I'm expecting myself in the future to travel back to the past (my future, his past) for whatever reason.
It might be to warn myself of a future disaster or something grand, so I can't simply get others involved.
I'm also a huge skeptic so since time-travel is real, why wouldn't there be a possibility that there are mind-readers?
How can I prepare myself to verify that someone is myself from the future?
Let's call my future time-traveler self "FTS" and my present average self "PAS".
My background is in Information Security, so my first thoughts come to Multi-Factor Authentication (MFA).
Something I know
Past Events
The easiest things to have FTS talk about an event in the past, especially something so embarrassing that I'd swear to take with me to the grave. However, human memory is finicky, so memories of past events are easily warped.
Passphrase to be remembered
I can try to memorize a passphrase and commit it to memory. This passphrase should be hard to forget, so the problem of bad memory should kinda be solved. However, mind-reading is a possibility, so someone can read the passphrase from my mind as I ask them about it.
Future Events
I can get FTS to state a future event. Something like the lottery would be too random and is easily changed thanks to the Butterfly Effect. 205
Big natural occurences like earthquakes would take too much time to verify, since we'd have to wait for them to happen. Mad-made events such as a crime have insufficient credibility, since FTS could just cause them after stating them, or stage the event to happen shortly after his statement on the event. Solar Weather seems like something an average would have a hard time verifying.
Something I have
What do I have now that can be reliably stored for decades?
I may get a big hard drive, put a lot of random data on it, and put it in a secure vault. However, having a single device would be too unreliable, and trying to put multiple drives in multiple different vaults maintained by reliable third parties would be too expensive for the average person. Also, whoever I entrust the drives to would be able to impersonate FTS, and I can't trust them.
Something I am
User fingerprints. This is cheap, fast, and simple. However, from what I've read, fingerprints are not as unique as Hollywood makes it out to be, and I can't be sure FTS will have the same number of fingers as PAS.
Just get a DNA test. This is currently my simplest idea. I'm no biology expert, but there probably isn't anyone that isn't me who would get the same results as me, right? But then again, as far as I know, DNA kinda changes over time, so it may not be as reliable as I'd hope. Additionally, FTS could have been exposed to some radiation that changed his DNA.
This is not a duplicate of 15448 since I'm just an average person without super powers.
This is not a duplicate of 12348 because I'm relying on myself alone to prove the time-travel. 284