Secret Codes #8

You've already learned how to use the Caesar cipher from Secret Codes #6. But UH OH, here's an enciphered text and we don't know the key! How will we solve it?

YMJXQJJUJWRZXYFBFPJS

One way to solve it is by using frequency analysis! The graph below shows the most common letters in the ciphertext.

frequency of letters

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Comments

Wow this was really hard. I…

Wow this was really hard. I had to leverage the clue, and look for a phrase that matched the patterns. Hint the 4 most common letters are E, T, A and O, but this cypher does not include any O.

To get the key, just compare the letters E and J. E is the most common letter in English, but J is the most common letter in this cipher. If E has been replaced by J, that should give you the key to the entire cipher. Every letter has been shifted that many places down the alphabet. To decipher the message, shift each letter back that same number of spaces in the alphabet.