Cryptographically secure hashes are Hard to get right, and harder to evaluate with any amount of certainty. History is littered with the dessicated failed corpses of roll-your-own crypto.
Madness string 4898
I mean, to quote the great academic paper of our time: Planes, Trains, and Plantains, the story of Oedipus, 'None of this makes much sense. Again, don't worry about it. This is a folk tale, not a God Damned Oxy-Clean commercial.'