Bitcoin vs Banks on Quantum FUD

I’m hearing a lot of bitcoiners incorrectly defending quantum FUD. They would say: the banks (or even nuclear weapon codes) will get cracked first before bitcoin. Yet banks have a much simpler defense: don’t use public key encryption.

I don’t see Quantum as a threat to bitcoin because (1) The Lindy effect of Quantum being just a hype; (2) difficulty of Quantum error correction; (3) quantum resistant protocols that bitcoin can adopt if Quantum ever becomes a real threat.

Still, I think it’s important to avoid making straw-man arguments when responding to Quantum FUD.

In public key encryption the attacker sees two things (1) the public key; (2) a bunch of gabbadyguck (the encrypted message, or in case of bitcoin: a signature). Yet banks can use non-public key encryption by giving you a special encryption passcode over the mail or at an office (sharing a secret privately) that you can use to do online banking. With that kind of encryption the attacker sees is a bunch of gabbadyguck (random sequence of bytes) and nothing else. That means that quantum cannot break your fiat bank.