Here’s a randomly generated cipher of unknown type. It took me a long time to solve because the cipher type is not included in my ID tests. My ID tests got the correct general category though. After trying the cipher types listed at the top of my ID tests, I got around to trying what turned out to be the correct type. But with no crib or any other additional information, I had to run a hill-climber many times until I spotted a partial phrase that made sense. I used the corrected phrase for a crib and after several more hill-climbing runs got the solution. I’ll include the phrase I spotted as a caesar-shifted crib.

???

HYPAD AITRN GETEF GONRR OGUIW AYEDC HEAEN GNWIE RCUTA ECAPI NPFTR

DCSSA FTESH RNDBS LEDYR WAOAH IAOTO RSRIE YLSTS BDFRI NDIOO CIORT

TMSES ANESD MORAB SFNN.

crib: KTW GTDX YBT KTW LNWQX

I’m pretty sure I know the type of this cipher, but I don’t have a solver for it. I wrote a converging keys solver for the type and ran it for most of the day yesterday, but it never produced anything that looked like plaintext, even partial plaintext or pieces of the crib. If I knew where the crib appeared, I might be able to solve it.

If the first plaintext letter is at position number 1, then the crib starts at position number 84.

It continues ETLVIRSPSKMWX. I was not able to find the key. It must be a word or phrase not in my normal word list. I’ll try to find it using other lists. Update: Other lists didn’t help, but I realized there is another way to represent the key. The encryption application has two options to check. My default is the one BION did not use. I found the key, which is a simple word.

That’s it!

The key is a common word, but this type of cipher always has four equivalent numerical keys that give the plaintext. So you may have to try all four to find the alphabetic key. Also you may have to convert (1-0) numerical order to (0-9) order if your search program is like mine and has to use 0-9 order.