Bitcoin's hashcash PoW is not a 256-bit search problem though. At current difficulty levels, it's closer to an 86-bit problem, so Grover's algorithm reduces tha

Bitcoin's hashcash PoW is not a 256-bit search problem though. At current difficulty levels, it's closer to an 86-bit problem, so Grover's algorithm reduces that to the equivalent of a 43 bit search space.