Israeli computer scientist helps crack secrets of Mary Queen of Scots’ lost letters

Secret coded letters written in cipher by Mary, Queen of Scots, between 1578 to 1584 - a few years before her beheading on this very day 436 years ago on February 8, 1587 - were uncovered by a multidisciplinary team of international codebreakers led by a leading Israeli computer scientist.

A study revealed 50 new letters in cipher – with some still believed missing – shedding new light on her captivity in an English prison by her cousin Queen Elizabeth I. One of the 16th century’s most famous historical figures, Mary was first in the line of succession to the English throne after her cousin.

Key themes referred to in Mary’s correspondence include complaints about her poor health and captivity conditions and her negotiations with Queen Elizabeth I for her release, which she claimed were not conducted in good faith.

George Lasry – a self-employed expert formerly of the Technion-Israel Institute of Technology in Haifa and a member of the DECRYPT and the CrypTool projects who obtained his doctorate with highest honors, as part of the research group Applied Information Security” (AIS) at Germany’s University of Kassel, in Germany – regards his cryptographic research as “an obsession, a passion.”

Cryptography is the computerized cryptanalysis of historical ciphers and cipher machines. “If I find a cipher,” Lasry said in a video interview, “I can’t let it go. Only after we cracked code were we able to see contents and understand who wrote them and about whom and during which era. It took two months to complete the job. We are not historians, but we have some ideas about history. Even as a child, she was aware of the need to keep communication confidential.”

He said that Mary, also known as Mary Stuart, learned how to create secret codes from the age of nine, taught by her mother. Mary. Queen of Scots was born at Linlithgow Palace to James V, King of Scots, and his French second wife, Mary of Guise. She was the only legitimate child of James to survive him. She was also the great-niece of Henry VIII of England, giving her a claim to the throne.

Contents of the letters were believed to have been lost

The contents of the letters were believed for centuries to have been lost, but that was until Lasry, Norbert Biermann (a pianist and music professor) and Satoshi Tomokiyo (a physicist and patents expert) stumbled upon them while looking through the national library of France’s – Bibliothèque nationale de France’s (BnF) – online archives for enciphered documents.

The BnF catalog listed them as from the first half of the 16th century and related to Italian matters. However, the study authors say they ‘quickly realized’ – after starting to crack the code – they were written in French and ‘had nothing to do with Italy’.

Their detective work revealed verbs and adverbs often in the feminine form, several mentions of captivity, and the name ‘Walsingham’ which arose the suspicion that they might be from Mary, Queen of Scots.

The three discovered Mary was the author only after solving her sophisticated cipher system. Their decipherment work of 57 letters is presented in the peer-reviewed journal Cryptologia under the title “Codebreakers crack secrets of Mary Queen of Scots’ lost letters.” reveals about 50 new scripts previously unknown to historians.

Mary’s correspondences expose fascinating insights into her captivity. Most are addressed to Michel de Castelnau de Mauvissière, the French ambassador to England. He was a supporter of Mary. a Catholic who was under the Earl of Shrewsbury’s custody when she wrote them.

“Upon deciphering the letters, I was very, very puzzled and it kind of felt surreal,” said Lasry, who is also part of the multi-disciplinary – involving several universities in Europe, with the goal of mapping, digitizing, transcribing and deciphering historical ciphers. “We have broken secret codes from kings and queens previously, and they’re very interesting, but with Mary, Queen of Scots it was remarkable as we had so many unpublished letters deciphered and because she is so famous. “This is a truly exciting discovery.”

“Together, the letters constitute a voluminous body of new primary material on Mary Stuart – about 50,000 words in total, shedding new light on some of her years of captivity in England,” Lasry revealed. “She has left an extensive corpus of letters held in various archives. There was prior evidence, however, that other letters from Mary Stuart were missing from those collections, such as those referenced in other sources but not found elsewhere. The letters we have deciphered … are most likely part of this lost secret correspondence.”

Catholics considered Mary to be the legitimate sovereign and Elizabeth had her imprisoned for 19 years because she was seen as a threat. Mary was eventually executed at the age of 44 for her alleged part in a plot to kill Elizabeth. During her time in captivity, Mary communicated with her associates and allies through extensive efforts to recruit messengers and to maintain secrecy. The existence of a confidential communication channel between Mary and Castelnau is well-known to historians, and even to the English government at the time.

Using computerized and manual techniques, the study authors decoded the letters which show the challenges Mary faced maintaining links with the outside world, how the letters were carried and by whom.

Her mistrust of Elizabeth’s spymaster Sir Francis Walsingham is also apparent, as well as her animosity for Robert Dudley, Earl of Leicester and a favorite of Elizabeth. She also expresses her distress when her son James (future King James I of England) is abducted in August 1582 and her feeling they have been abandoned by France.

This fact was confirmed by comparing them with the plaintext of letters in Walsingham’s papers in the British Library and through other methods. A search for similar letters in BnF collections uncovered 57 letters with the same cipher.

The authors suggest that other enciphered letters from Mary which are known to have existed may still be missing. A physical inspection of documents, as well as online searches, are needed to uncover these, they add.

It is hoped, now too, that the study will lead to future research.

“In our paper, we only provide an initial interpretation and summaries of the letters. A deeper analysis by historians could result in a better understanding of Mary’s years in captivity,” Lasry concluded. “It would also be great, potentially, to work with historians to produce an edited book of her letters deciphered, annotated, and translated.”