Given there are SHA256 engines that produce terahashes per second, you could probably do tens to hundreds of terahashes depending on sophistication. At that po

Given there are SHA256 engines that produce terahashes per second, you could probably do tens to hundreds of terahashes depending on sophistication. At that point even a sloppy brute-force approach would have a high probability of a collision on at least one key of a sufficiently large key-set. Against a specific target it may or may not be viable.