Breaking 19th Century Encrypted Newspaper Ads With Modern Means

Elonka Dunin and A.J. Jacobs present a collection of encrypted classified advertisements printed in English, French and American newspapers during the 1800s. Their co-author Klaus Schmeh could not attend, so the two presenters covered the material between them. Newspapers were read in port cities around the world, which made printed notices a practical way to pass messages, and many notices were enciphered to keep their contents private.

The talk moves through several case studies. The best known is a run of ads from the 1850s linked to a search for the Franklin expedition in the Arctic. That cipher was eventually solved by spotting common words, such as the name of a month or the word for sun, and matching them against a code book from the period. Other examples include romantic exchanges broken with frequency analysis, a message from 1873 cracked with software that tests letter patterns against English words, and a 1902 ad that was only solved in 2014 after its alternating letters were split into two sequences. A single Denver ad that remains unsolved is also covered, along with ciphers from the Enola Holmes film and the coded notices of private detective Ignatius Paliki.

The presenters close by inviting the audience to help with the messages still open. They point to free software and online services as practical starting points. The main takeaway is that substitution and code-book methods, combined with historical context and open tools, can still reveal old messages, and that many others remain open puzzles.