Unknown 7-9-2019

Here’s a randomly generated cipher of unknown type. I had a hard time solving it. Within a certain range of periods all my ID tests got the correct type. But this period range was not correct for this cipher! With a different range none of my ID tests put the correct type on top. I tried a lot of different hill-climbing combinations and finally hit on the correct combination. With the correct combination of settings the hill-climber solved it without a crib. I’ll include a caesar-shifted crib.

???
NGKSF SBZUG AINZX BHNZL MALKZ KCTIS EBUSF MNIPA HIIFQ NAOKR JJIHR
RKBCC KHBZE VSVUI PGOAP UDGVM YXXBA PHHNC WNTYL WKNBA GPABN XBUWB
NZBJJ GIYUR.

caesar-shifted crib: XMTB

3 thoughts on “Unknown 7-9-2019”

    1. My analyzer put Beaufort on top, followed closely by Quagmire and then all the other Vigenere family plus Gromark, then Progressive Key, Portax and Slidefair. That’s 11 types. I didn’t try Gromark since that’s not a periodic type, but I’ve tried all of the others using both the crib and the hint information. Most of my solvers didn’t have the range to hillclimb the correct period, so I modified them, but still had no luck. My Analyzer also may be inaccurate because it depends in part on the index of coincidence over a range of periods that didn’t include the correct one. I think this one has defeated me.

  1. Cipher Type: RNCJI UWTLWJXXNAJ PJD, GJFZKTWY PJD GZY ANLJSJWJ UWTLWJXXNTS NSIJC.

    I have a “one-pass” solver for this general cipher type. With maximum period set at 20, it did get the correct period, but not the correct plaintext. It uses log digraph scoring. I had to use a hill-climber with log tetragraph scoring to get the correct plaintext.

    It looks like the randomly selected key word was a little too long for the randomly selected text.

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