Mary Queen of Scot’s Encoded Letters Deciphered by an International Cryptographers’ Team

The researchers deciphered the meaning of the symbols used in Mary Stuart’s letters. Credit: Lasry, Biermann, Tomokiyo

Five centuries of secrets have been unearthed by a team of international cryptographers. The protagonist of the 16-century significant political turmoil in Great Britain, Mary the queen of Scots had sent letters to the French ambassador that were decoded with the help of computers recently.

It was more than 50 letters from Mary the Queen of Scots, sent between 1578 and 1584 to the French ambassador, Michel de Castelnau Mauvissière during the rule of Elizabeth I. The letters from Queen Mary I called Mary Stuart, included concerns about her health issues and hopes for release from her imprisonment by Queen Elizabeth I. Mary Stuart was in the custody of the Earl of Shrewsbury because her sister’s political power collided with hers. A letter was written in 1586 that led to Mary’s doom.

One of Elizabeth’s spies, Sir Francis Walsingham, tricked Mary into believing her letters were secure and intercepted one supporting Elizabeth’s assassination. As a result, Mary would be beheaded for treason in 1587, according to ScientificAmerican.com.

Cryptographer George Lasry of the DECRYPT Project, which is a collaboration of historical ciphers at multi-universities around the globe, have been combing through the archives at BnF when they came across pages of ciphers mixed in with documents from Italy dating to the early 1500s. The ciphered letters were believed to be Italian, and the researchers began to try to crack the code. They found the letters used a homophonic cipher that used certain letters, “e” in particular symbols. Lasry says Mary’s cipher used symbols which it was high-frequency words and common word segments. “The cipher was quite complex, and we worked in phases,” Lasry says.

“It’s a stunning piece of research, and these discoveries will be a literary and historical sensation,” said Dr. John Guy of Clare College Cambridge, the leading historian of Mary Queen of Scots.