Yeah, my idea makes more sense if you omit the 64-byte limit; then the input can be an entire book. For an ideal hash function, every output maps to an infinit

Yeah, my idea makes more sense if you omit the 64-byte limit; then the input can be an entire book. For an ideal hash function, every output maps to an infinite number of inputs. I don't know if SHA-256 has that property, but God could just define the simplest ideal hash function and let people cryptanalyze it.