Running Key 5-25-2019

Here’s one more Vigenere running key cipher. It took me a long time to solve this using the word/phrase search program and the combination interactive solver and hill-climber. I kept going back and forth between all 3 of these. The initial search turned up a pretty good phrase, which I’ll include in caesar-shifted form. But I still had to do a lot more searches with various options. The searches did turn up the short initial word, and the longer word at position 23 (relative to starting at 0). With the position 23 word in place, the hill-climber got the exact solution. I’ll include a screenshot of the word/phrase search options.

Vigenere running key

caesar-shifted crib: NRZXYHTSKJXX


2 thoughts on “Running Key 5-25-2019”

  1. I was able to derive the first six words and the offsetting key letters without using the crib, which would have been enough for ACA credit, but it became a slog to finish. The beginning and ends of the key and pt words kept landing in the same place, making it difficult to get the continuation. I gave up at that point and looked up the quote.

    1. Yes, the seventh word (which begins at position 23) was hard to find. My hill-climber never found it. As you mentioned, the plaintext corresponding to the 7th word also begins at a word boundary. I do have an option in the word search program to only consider plaintext strings that begin at a word boundary (as opposed to begining with a word suffix ). Fortunately the beginning of the plaintext at position 23 was in my phrase list as a string of 5 letters consisting of 3 short words. In fact, the correct seventh word was the first one that turned up in the word search output.

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