GUW SHLXFHC XJSXZWJG FO
GUW ZFT XJ GUW JXTUG – GXPW
Above is the title of one of my favourite books, encrypted.
To crack it, start looking for patterns, bearing in mind the following facts about written English:
The most common letters: E, T, A, O, I, N, S, H, R
Most common starting letters: T, O, A, W, B, C, D, S, F, R
Most common finishing letters: E, S, T, D, N, R, Y, F, L, O
Most common words: THE, BE, TO, OF, AND, A, IN, THAT, HAVE, I
Do you see the repeated GUW?
That is most likely to be the most common word in the language, the, so that’s what we’d try first.
If G stands for t, U stands for h and W stands for e in that word, they will do so everywhere in the cipher. So we replace all of them to get to:
