If you have a "master password", for something like KeePass, which can then decrypt everything else, how do you ensure that you would always be able to remember that original password?
For example, say you get in some accident and you lose your memory of the password, or maybe you just get older and gradually forget it. Maybe you encrypt a drive, and think you've lost it, and find it later but can't remember what password you used originally.
How could you be sure that you could always figure out your password, even with brain damage, but no one else could ever figure it out?
I was thinking, maybe some sort of steganographic tattoo? Writing the password down is obviously the worst option, but if you can do it in a way that isn't obvious, you could perhaps jump start your memory enough to proceed. Even then though, I can't think of any numeric values, or other unique (yet secret) identifiers a human has outside of their own mind.
maybe the answer is "if your brain fails in that way, the data is gone forever." but surely there must be a better solution. Even in military situations, surely there is no mission-critical data that is stored solely in the mind of a person.