# Determining if at least 1 bit is set in the output of SHA256

Given the SHA256 hashing algorithm, is there any shortcut to determine whether 1 bit will be set in the output in a given position (or set of positions)? Relaxing the question a little bit, is there any probabilistic test (simpler than performing a full hash of course) to tell if a bit will be set (with probability 1) or not set (with probability <1)?

• Should that last probability not be 1 as well? I can tell if a bit is unset with probability 0.5 without any problem at all. Dec 19, 2017 at 14:18
• @MaartenBodewes I mean a probabilistic outcome as some primality tests: this number is not prime with probability 1 or it is prime with probability <1 Dec 19, 2017 at 14:22