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Codes that were never there

The hardest lesson in code-breaking, and the most useful one outside it.

Every letter here is random

A computer picked them, one at a time, with no plan at all. There is no message, no author and no code.

Now slide the spacing. Take every seventh letter, or every twelfth, and look for a word. You will find one. Change the spacing and you will find another.

That is not a discovery. It is arithmetic. There are hundreds of chances for a short word to turn up, and something always does.

Three famous ones

Shakespeare. People have claimed for centuries that messages are hidden in the plays. William and Elizabeth Friedman, the finest code-breakers America produced, took the claims apart in 1957 and showed the messages only appear if you let yourself change the rules as you go: take these letters and not those, count this way here and that way there.

The Bible code. Skip a fixed number of letters through a long text and words appear. They appear in any long text, including novels and this page. That is what the box above is showing you.

Pi. The digits run forever without repeating, which means every number you can imagine turns up somewhere: your birthday, your phone number, eventually anything. None of it was put there.

The rule that protects you

A real code-breaker fixes the rule before looking, and then keeps it. If you are allowed to adjust the rule until something appears, you will always make something appear, and it will mean nothing.

That is why the identification page exists, and why the hardest answer a code-breaker can give is this is nothing. Wherever somebody shows you a pattern, the question is always the same: did you decide what counted before you started looking?

What am I looking at? Frequency analysis All the ciphers

Read more elsewhere

Longer, harder and written for grown-ups. Worth a look when this page runs out.

Cryptanalysis