Change the pow to have a predictable clock time (#31)
Change the pow to have a predictable clock time (#31)

Currently the pow is random depending on the seed, which is prone to precomputation, and to parallelization probing for a cheaper challenge. This pow is not parallelizable, isn't prone to precomputation or challenge selection, and has a deterministic clock time.
google/kctf,google/kctf,google/kctf