Running key 5-21-19

Here’s a randomly generated Vigenere Running key cipher. I was able to solve it without a crib by using a program that drags a huge list of phrases across the cipher and uses logs of digraphs to score the corresponding plaintext strings. If the log digraph score of a plaintext string is high enough then the string is parsed into individual words (and partial words at the beginning and end of the string). If the parse is successful and one of the plaintext words is long enough then the phrase and corresponding plaintext string is saved to disk.

I set the length of a plaintext word to 7 or more letters. With this setting I got 35 phrase-plaintext pairs out of about 600,000 starting phrases. I used these 35 results as a collection of cribs and was then able to get the solution with a combination interactive and hill-climbing running key solver.

I’ll include a caesar-shifted crib.

Vigenere Running key:


Incidentally, the new version of the phrase dragging program is written in javascript, with the node.js javascript framework supplying disk input/output. I recently bought a new Chromebook (a Pixelbook actually) and discovered it had a setting for activating Linux. I clicked on the “setup Linux” button and in about two minutes I had a Linux terminal running. I used the terminal to install node.js and was eventually able to run my phrase dragging program using Linux.

2 thoughts on “Running key 5-21-19”

  1. It continues IEXAY. I solved it without a crib. I don’t have such a fancy setup as you describe, but I use a similar approach with word lists. In this case I ran through my word list and the best scoring decryption turned up opposite the crib, although I didn’t realize it at the time. From there I worked it by hand to extend the crib a bit and searched online with the pieces I had and the quote turned up. I wasn’t actually looking for the solution. I just wanted to extend the crib farther.

Leave a Reply

Your email address will not be published. Required fields are marked *