I seem to only have it in me to write a short post this week, so I’m going to tell you briefly about two ciphers that baffled cryptographers for decades, if not centuries, before being cracked.

The Copiale Cipher is a 105-page document dating back to 1760-1780 that was deciphered in 2011. It contains 90 different symbols with a total of 75,000 characters. Discovered in the archive of the East Berlin Academy and now held in a private collection, the Copiale Cipher was cracked by an American computer scientist (Kevin Knight) and two Swedish linguists (Beáta Megyesi and Christiane Schaefer). It turns out the book belonged to a German secret society focused on ophthalmology! Read more here.

The other cipher I read about was more recently written and solved. It’s a 340-character message written by the Zodiac Killer, a serial killer active in the San Francisco area in the 1960s and 70s. The message was sent to the San Francisco Chronicle in November 1969 (the second of four coded messages — the first was cracked in one week) and solved in December 2020 by three collaborators from the United States (David Oranchak), Australia (Sam Blake), and Belgium (Jarl van Eycke). The message, which was validated by the FBI, did not reveal the identity of the Zodiac Killer. Read more here and here.

I know none of this is exactly breaking news, but remember when I recently posted about ciphers sent by Mary Queen of Scots? I think it’s neat that in all three of these cases it was an international team that finally cracked the ciphers.