Cool.
The old link below appeared 404ed. Singh’s site was worth the look. Thanks again KF.
I’ve noticed that if you group k4 to end rows on the doubles that all but otwtqsjqss and ekzz are multiples of 7, and those two combine into another multiple of 7… perhaps you’re on the right track with secondary encipherment, but the iterations run for aperiodic lengths. ekzz is interesting to me because if k4 is 98 characters it ends half way through at 49, but if you count it as part of the second half the unique letters to each “half” are at their largest quantity.