Since my early teens (back in the early 70’s) I’ve been fascinated by the art and science of cryptography and cryptanalysis. It was in David Kahn’s magnum opus “The Codebreakers” that I was first introduced to the Chaocipher.
The Chaocipher was a cipher device invented by John F. Byrne in 1918. Byrne, a close friend of James Joyce, was the model for Joyce’s Portrait of the Artist as a Young Man, and Joyce made Byrne’s residence, 7 Eccles Street, Dublin, the home of Leopold and Mollie Bloom, the two protagonists of his great Ulysses.
For the next 40 years, Byrne tried to interest numerous government and public organizations in the Chaocipher. These included the US Army, Navy, Signal Corp, the State Department, and A. T. & T. Although the device was welcomed by some, he was greatly frustrated and disappointed that none took him up on the offer.
In 1953 Byrne published his autobiography Silent Year: An Autobiography with Memoirs of James Joyce and Our Ireland. The book recounted Byrne’s memories about Joyce, but the real reason for publishing it was the 21st and last chapter entitled “Chaocipher”. In it he recounted the entire story of the Chaocipher, presented four large cribs of corresponding plaintext and ciphertext, and challenged anyone to solve several encrypted lines. He bet $5,000 or the total royalties of the first three months after publication of his book that the cipher would remain unsolved.
Today, fifty-six years after the publication of Silent Years, the Chaocipher remains unsolved. It is listed in Elonka Dunin’s list of unsolved codes and ciphers. Two articles in Cryptologia discussed the cipher, but very little material about it was available on the web.
Much of the apathy and disinterest is due to Byrne’s secretiveness about the inner working of the Chaocipher, raising the cryptological community’s ire by adopting “security by obscurity”. I agree with others that Byrne was wrong in not divulging the mechanism, letting cryptanalysts determine the security of the underlying principle. Nonetheless, the Chaocipher is not the work of your run-of-the-mill “my cipher is unbreakable” cryptographic wannabe. It is challenging enough to warrant rising to the challenge, solving, and putting it to rest once and for all.
Last week I decided to change the state of things by announcing a web site entitled “The Chaocipher Clearing House“. The site presents links to basic Chaocipher resources and includes a summary of my research to date. My wish to see this cipher solved greatly outweighs my need for immortality: if the site helps someone else solve the Chaocipher, I will sleep better at night. 🙂