What material they use to make those Black-Boxes inside an Aeroplane, that thing can take a good beating and it seem to survive in heat, water, etc. It'd be pretty safe to put some keys inside a safe box made of the same material.
But the thing is none of these things are safe from physical theft, they may last for life long but if a thief is able to get to them, they will be able to swipe off the key and steal the funds, they don't even need to move the carved stone or whatever and when and if bitcoin gets more mainstream we will see more robberies to steal people's stacked bitcoins.
BIP38 encryption? IMO, they are pretty secure from bruteforcing if you choose a hard password. Of course, this wouldn't be viable if you do lose your password but you can still store the password somewhere safe, far away from your paper wallet. Alternatively, multi sigs can potentially prevent this problem by either placing them at a few secure locations or with a few of your trusted friends. If you need to spend it, you would at least need m of n of the signatures. This would protect against theft and it would provide redundancy.
It's a solution alright, you encrypt the key, engrave the key on the stone, it will last forever and you don't have to worry about someone stealing the funds because without the password it can't be used. But I don't think I can trust myself to remember a strong password which is big enough, has no dictionary words, contains alphanumeric, small & capital letters and special characters, I would need to write it down somewhere. So the question again comes down to where to store the password?? Carve it on a stone?
I think for now I am just going to use the traditional approach, put the key on different encrypted USBs and print 'em on paper and put them all in a safe place and try to protect it from Damage/Theft myself.
BTW, how much does the machine that carve things on stone like Tungsten costs? I'd imagine it won't be any cheap.
This sounds nice (although it doesn't provide protection from damage like fire etc.) no other type of hardware needed, just put them on the dvd burner and burn your key on them and if what they say is right, it'll last a 1000 years and the pack of 3 is cheap. I might give this a shot.
