Artificial Intelligence Helps Scientists Decode Secret Letters from the Past, Revealing Unpublished Historical Information and Driving Advances in Research
The cryptography plays a crucial role in data protection and cybersecurity today. It prevents unauthorized individuals from accessing transmitted or stored information. However, the practice of sending secret letters or messages is ancient.
Since ancient times, cipher systems have been used to convey secrets, relying on keys shared only between the intended recipients.
Secrets in Codes: How Ciphers Work
A cipher system transforms information into codes that can only be understood with a key. For example, each letter may be derived from numbers or other symbols. This substitution can be questioned, making it difficult to identify patterns.
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The complexity increases even further when each letter can correspond to different numbers. Without the right key, deciphering these messages is a true challenge.
Michelle Waldispühl, a German professor at the University of Oslo, explains: “The key is shared only among the people who should be able to read it. One person encrypts, and the other decrypts using the key.”
The Secret Letters of Mary Stuart
An impressive discovery occurred at the French National Library. Researcher George Lasry found over 50 secret encrypted letters written by Mary Stuart, the former Queen of Scotland.
These secret letters were sent from her cell to the French ambassador in England, while she was imprisoned for conspiring against her cousin, Elizabeth I of England.
The letters were archived unusually, as no one had been able to decipher them before. The Guardian described this finding as the most significant discovery about Mary Stuart in over a century.
The messages reveal political conspiracies and complex strategies, offering a new perspective on a historical period marked by betrayals and power struggles.
Negotiations, War, and Love in Code
The work of Waldispühl and her colleagues was not limited to the letters of Mary Stuart. They also analyzed documents from Axel Oxenstierna, Chancellor of Sweden, during the Thirty Years’ War (1618-1648).
These letters dealt with war reports, peace talks, and diplomatic negotiations. Sensitive information, such as names of people and places, was encrypted. However, in times of urgency, only the most critical data was coded.
In addition to diplomatic and military issues, love also found its place in secret codes. A private collector presented over 400 postcards containing encrypted writing, dated from the late 19th century to the early 20th century.
A postcard from 1908 caught attention. The message began in a totally illegible way: “=voevoeeoggvkov/l“.
After partial deciphering, it revealed a romantic message in German: “Meine innig geliebte einzige herzensgute Miezefrau,” translated as “My dear and only good-hearted kitten“.
The Enigma Machine and the Human Role in Cryptography
During World War II, cryptography evolved to even more sophisticated levels. The Enigma machine used by the Nazis is an emblematic example.
Alan Turing and his British team played a crucial role in breaking the Enigma code, using machines and innovative techniques for the time.
However, even with technological advancements, the human element remains essential. Waldispühl emphasizes the importance of the so-called “human-in-the-loop.” Often, there is little material available to train language models, necessitating detailed human analysis.
For example, when transcribing encoded documents, computer scientists need linguists’ review to correct subtle details, such as commas and marks on characters. These settings can be decisive for the correct interpretation of the content.
Secret Letters: Unraveling a Sixteenth-Century Mystery
In a specific case, a completely coded letter turned out to be an important political document. After intense manual and digital analysis, it was found to be campaign propaganda from Holy Roman Emperor Maximilian II.
The letter contained promises and threats aimed at representatives of the Polish-Lithuanian Commonwealth in the 1570s.
This episode demonstrates how encrypted messages can contain restricted information about historical events and political strategies, reflecting the interests and ambitions of the powerful of the time.
Artificial Intelligence to Solve Ancient Mysteries
Waldispühl and her team compiled thousands of encoded documents into a database called de-crypt.org. But the group’s plans go beyond deciphering old letters.
They aim to develop models and tools to interpret other writing systems and symbols, even when little data is available.
Among the challenges recommended by Waldispühl are “Linear B,” an ancient Greek writing system, and the Phaistos Disc, 4,000 years old, found in Crete and still undeciphered. These mysteries remain unsolved, but technological advancements might change that.
Technology Accessible to Everyone
The ultimate goal of the team is to make these tools accessible. Waldispühl dreams of a future where anyone can photograph a document with their cellphone and receive a complete translation and analysis in seconds.
This advancement would benefit not only historians and linguists but anyone interested in exploring and understanding coded messages from the past.
After all, cryptography, which started as a tool for kings and spies, may soon be within everyone’s reach, revealing forgotten stories and secrets kept for centuries.
With information from Tech Xplore.

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