Quote from: signer on August 29, 2023, 08:39:58 PM

I finally found the backup I wrote down after using Gavin Andresen's Bitcoin faucet. I don't remember if I was using only Bitcoin Core, Armory, or something like Multi-bit. Those sound familiar.

There are 5 bitcoins in the first address and I never moved or used them. The characters I found on my handwritten paper backup are 80 characters, between (0-9) and (A-F). I wrote these in blocks of four characters. Within these 80 characters, I have 14 question marks. So a total of 66 known characters. I'm not sure if I only need 64, 66, or 80 characters total.

I have Bitcoin Core and Electrs downloaded on my Umbrel to start trying the recovery process. I also have Electrum and Armory downloaded.

I'm not sure the best course to go from here to find out what the key may be and how long it should be. I'm not in a hurry and have time to try to figure this out, hopefully with your help.

Offering a full Bitcoin to the best helper.

Do you have any reference as to what the questionmark characters might be? Might be worth to try hypnotherapy, not sure if there is real science that this can work, but I guess it wouldn't hurt to try.
A typical case of making it too secure for your own good. I have done similar things myself in the past, so not blaming you. It's human nature, expecially back in the day when there was not a bunch of publicly available resources regarding crypto floating around.
It's something I heard Andreas Antonopoulos warn about again and again. In the moment it seems like a cool and logical thing to somehow add some encryption to your written backup. - Personally I noticed that sometimes even within 1 year I have no clue what I was thinking back then.

I wish you the best of luck to successfully restore your wallet. Given the fact that it's "only" 14 characters missing there is a good chance at some point within the foreseeable future it will be crackable by a strong (cloud)-computing-network within a reasonable timeframe.
https://www.proxynova.com/tools/brute-force-calculator/ currently gives an estimate of ~1000 years, but I think that's based on the time it takes an average home computer to crack this. Meaning a powerful super-computer could quite likely already crack it within a few days or weeks.
With the current rate of Bitcoin this is most likely still not worth it, but if Bitcoin climbs up to $1M/BTC and computational power is getting cheaper and cheaper in the meantime, it will most likely be a profitable thing to crack.