CM Bifid 9-23-19

Here’s a randomly generated period 7 CM bifid cipher. I originally tried it as unknown. One of my ID tests put CM bifid on top but I didn’t know the period. I tried various periods using converging key search and period 7 scored the highest but I didn’t include the correct range of routes to get the solution. I looked up the period and then was finally able to guess a correct range of possible routes so that converging key search got the solution. I’ll add a caesar-shifted crib.

CM bifid, period 7:
FEMQY KFTQL WHYFT UGKDI KTRUX MGNMA LYEAG BMAYY EIQFO YTKIC QLAHY
DXCLX XIKLH PBKKF TUSDS FZVQW DRFIR FTGAN PTLHK DDKTA NKDIR COFXK
KSTTR DAPIM LLMLB KATGY PYFFE TTSOA FTQXX SXUBG OADKB HEXVK BXTX

crib: HYNAJTGOJHYNAJNIT

2 thoughts on “CM Bifid 9-23-19”

  1. I finally got it. My Analyzer put CM Bifid as a close second to Foursquare. Neither my hill-climber nor my Converging Keys solvers made any progress with it. I resorted to a key search program using the crib and at first had no luck with that. I had to go through my source code carefully and finally spotted where I’d entered a single wrong letter (switching row and column for one letter, thus eliminating the correct key word). It continues XLICWIIQIH.

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