Cryptograms through literature

The most famous of them all is still "The Adventure of the Dancing Men", a 1903 short story by Arthur Conan Doyle. Sherlock Holmes deciphers a series of wriggling stick figures sent from Chicago to Hilton Cubitt.

A pure, straight monoalphabetic substitution, broken by frequency analysis in a matter of hours. Doyle is said to have been inspired by a real cryptogram from a reader’s correspondence. Since then the dancing-men alphabet has become an icon — on book covers, in escape rooms, on geek t-shirts.

The Beale ciphers are just as mythic, but they never found their Sherlock. Three pages of numbers published in 1885 by James B. Ward, supposedly leading to a forty-million-dollar treasure buried in Virginia in 1820 by a certain Thomas J. Beale.

The second page was broken in 1885 — it used the American Declaration of Independence as its book-key. Pages 1 and 3 still hold today, and have nurtured a whole sub-genre of American cryptographic literature for one hundred and forty years.

Other literary enigmas fascinate by their longevity: the Dorabella letter sent by composer Edward Elgar in 1897 to Dora Penny — 87 symbols shaped like overturned, stretched-out Es, never deciphered despite 125 years of effort.

Kryptos, Jim Sanborn’s sculpture installed in 1990 in the CIA’s Langley courtyard, has given up three of its four panels but the fourth holds after 35 years. The Zodiac Killer’s Z408 fell in a week in 1969, but the Z340 held until December 2020 when David Oranchak and his team finally cracked it.

What makes these literary cryptograms fascinating is that they are never purely technical. Each is wrapped in a story: a thwarted love letter, a mythical treasure, a criminal signature, a challenge thrown at the most powerful intelligence agency in the world.

Cryptanalysis then becomes a historical investigation as much as a mathematical chess game — exactly what Poe theorised in 1841 in A Few Words on Secret Writing, where he dared his readers to send him a cipher he could not break. He broke every single one he received.