A Lesson in Ciphers # 9 Mystery Cache

This cache series is designed to give you an introduction to the world of ciphers. It will not cover every type of cipher out there, instead focusing on a small variety of different ciphers. Hopefully, you will walk away from solving this series with a new set of puzzle solving skills. And maybe, just maybe, you'll be able to go to that puzzle that's always bothered you and begin to see it with a new pair of eyes.

I have designed this series such that you will not be able to solve them all in one swipe. How you may ask? Outside of the first two caches, all of the caches in the series will require clues left within previous caches. I recommend that you keep track of these clues, and which cache they were found within, as you work your way through the series. That information will be useful even after you solve the cipher it is used with. On to the cache.

I've mentioned in past lessons that without full knowledge of how the cipher was encoded, you are at a disadvantage with decoding it. So what can be done to help increase your chances?

You've heard about Frequency Analysis in previous lessons. Let's look more closely. It is one of the most powerful tools in cryptoanalysis. Anyone who has ever done any writing has learned that some letters show up more than others. Over time, averages can be developed for how often letters appear. The phrase ETAOIN SHRDLU is commonly used to reflect the twelve most commonly used letters in the English language. Throw in the rest of the letters in the English alphabet to get:

Frequency analysis can be useful in helping to identify letters used in a cipher. The idea is that by determining a few letters, you can start to form some of the more commonly used words. From there, you can take guesses at other words and start to figure out what the KA is. Does it always work? The quick answer is no, but it can be a useful strategy.

The order of the most commonly used letters varies depending on the text. You obviously need a large amount of text to really test true averages, but the type of text can make a difference. For example, historical documents, scientific documents, religious documents, and even what you find in newspapers and magazines can alter the order of the letters. For a quick reference of commonly used letters and words, using different paramaters, check out Letter Frequency.

Use a key from a previous cipher to solve the following and learn where you need to go to complete this lesson:

As always, be wary of muggles and try to rehide this as you found it. Parking is nearby.

Need a refresher on a previous lesson? Here's the complete list (updated as the lessons become available):