Friday, January 02, 2009

A Crypto Problem

My #3 Son was reading Poe's The Gold Bug and so he and I were discussing solving crypto puzzles. My son mentioned the letter frequencies Poe gave and I said Poe was wrong. So I asked him if he was sure he remembered it correctly. My son said he was sure he remembered it correctly and got the book out to prove it. Of course I had read Poe many years ago, but I didn't remember the letter frequencies Poe gave. Here are the letter frequencies Poe gave in order from most common to least as:

e a o i d h n r s t u y c f g l m w b k p q x z

In Linotype usage the frequencies are:

e t a o i n s h r d l u c m f w y p v b g k q j x z

and like any good crypto puzzle solver let me put them one on top of the other:

e a o i d h n r s t u y c f g l m w b k p q x z
e t a o i n s h r d l u c m f w y p v b g k q j x z

Do any of you have an explanation for the differences at least among the most common letters? Was he trying to make it harder for his readers to solve the crypto puzzles he often published?

Should you care to read or re-read the story here is an on line version of The Gold Bug from Project Gutenberg. And here is a paperback version: The Gold-Bug and Other Tales.

Cross Posted at Classical Values


Alex Green said...


Intriguingly, this is the ranking for a book cipher which uses the first letter of each word.

The ranking for first letters in English is

t o a w b c d s f m r h i y e g l n o u j k

whereas that for every letter in english is as you quoted.

If you multiply the numerical frequencies for first letters by the numerical frequencies for every letter, the ranking will be close to that given by Poe.

Best regards,


M. Simon said...


Very interesting.