Codebreakers Find ‘Sexts,’ Arctic Dispatches in 200-Year-Old Encrypted Newspaper Ads

Between 1850 and 1855, someone published a series of unusual ads in the British newspaper The Times. They were made up of a series of seemingly random letters, apparently gobbledygook. Almost 200 years later, a group of codebreakers has finally been able to decrypt some of them and read what they said, discovering that they were actually encrypted messages from a rescue expedition in the Arctic Ocean.  

“We could potentially call this the first known secure global communication system in the 1800s,” Elonka Dunin, one of the cryptography enthusiasts who decrypted the messages, said during a talk at the Hackers on Planet Earth conference in Queens on Saturday. 

The story of the ads starts in 1845, when explorer Lord John Franklin set out from England on an expedition with two warships called Terror and Erebus with the goal of finding the Northwest Passage, a sea route that connects the Atlantic and Pacific oceans through the Arctic Ocean—a faster way to get from England to India and the rest of Asia. 

Three years later, Franklin and his 129 men vanished and were never heard from again. 

In 1850, the English naval officer Richard Collinson was sent to the Canadian Arctic in hopes of finding any traces of the Franklin expedition, or at least figuring out what happened to the explorer and his ships. Collinson’s ultimately failed expedition lasted from 1850 to 1855, exactly the same time period of the encrypted ads published in The Times. 

“Was there a relationship between the encrypted ad and Northwest Passage, or the Franklin Expedition?” Dunin asked during the talk. 

With that working hypothesis, Dunin, along with journalist A.J. Jacobs and cryptography expert Klaus Schmeh, started analyzing the ads in an attempt to figure out the encryption method, which would allow them to decrypt it and uncover their meaning. 

Past decryption attempts had already failed. In 1980, The Times had republished one of the ads, asking readers to decrypt it. No one was able to, but one reader pointed out that it looked like the message contained latitude and longitude coordinates. Then in 1992, cryptographer John Rabson wrote about the ads in his journal Cryptologia identifying specific patterns in the ads, which gave Dunin and her fellow codebreakers a lead to follow.

With that knowledge, Dunin explained that she and the two other codebreakers started looking at groups of four and three letters in the encrypted messages. All letters in these groups were G to Q, and there were also capital letters only from B to F, and there were also bits and pieces of cleartext sprinkled through the messages. At that point, they thought there may be a codebook which contained the system that would help them decrypt the messages.

But, she said, at first they couldn’t find one. What they did find was a codebook, the Marryat signal code from 1817. This codebook uses four-digit groups or numbered groups, as a system for sailors to send each other encrypted messages using flags, which represent different numbers. Dunin and her colleagues then replaced the letters in the encrypted ads with digits, first zero to nine, which didn’t work, and then nine to zero. 

“And that turned out to actually be the system that was being used. So we replaced the letters with the digits contained in the code and we did get the plaintext,” Dunin said. 

The decryption revealed that the ads were messages sent back and forth between the Collinson expedition members and their relatives and families back in England. For example, they contained notes about where they were, and how they were doing, such as “your wife and family are well,” according to Dunin. 

“Why did they do this in The Times? Well, they knew that no matter where the ship would go, that The Times was readily available in any city around the world. And this was their way of communicating,” Dunin said. 

Unfortunately, as far as they can tell, the system worked only once in 1855, when Collinson obtained four copies of The Times when he was in the Indonesian town of Banyuwangi, and “was able to get some news from home that way” in a message addressed to him, according to Dunin.

Not all the 50 messages sent as newspaper ads from 1850 to 1855 have been decrypted yet, so Dunin challenged the conference attendees to give it a try. In fact, anyone can look at the ads on a newspaper archive website and help them out. 

The reward would be to find a missing piece of the puzzle that is a centuries old expedition. 

For Dunin solving ciphers like the encrypted newspaper ads “is a wonderful lens into the past.”

During the talk, Jacobs shared another lens into the past, one that is not as high stakes as the Collinson messages: classified encrypted newspaper ads that were actually messages between lovers, “sort of the sexting of the 19th century,” Jacobs joked. 

Jacobs shared several messages, including one from 1856, which read: “I have the most beautiful horse in England, but not the most beautiful lady. Your silence pains me deeply. I cannot forget you.”

He shared other examples, but as Dunin said earlier, there are still a lot of messages left to be decrypted.

“There are many out there that are still to be solved. So I encourage people to look into it,” Jacobs said. “Because it's a fun puzzle. Of course, we want them all cracked.”

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