"The point of this competition was not just to replace SHA2, but to develop a collection of new defensive techniques so that we can deal with attacks if they ever arrive," Green said. "And it was also intended to advance our knowledge in the area of hash function design. It's done a great job of that."

Green is concerned that if NIST doesn't select a winner this time, a future competition of this nature would not be met with the same level of enthusiasm from cryptographers.

"One place I absolutely agree with Bruce is that we should take our time transitioning from SHA2 to whichever function becomes SHA3," Green said. "But what's great about this competition is that we'll at least have something to transition to."