American study reveals methods of securing royal correspondence in 16th century

CAIRO – 13 January 2022: To protect the most important royal correspondence from spies in the 16th century, writers used sophisticated security measures where they folded the tip of the letter, then hung a ribbon and sewed it from the outside, so if a spy untied the thread, it would be impossible not to detect it.

According to the American New York Times website, Catherine de Medici used this method in 1570. It was the time when she ruled France while her sick son, King Charles IX, sat on the throne. Queen Elizabeth I did so in 1573 as Sovereign Ruler of England and Ireland. Mary Queen of Scots used it in 1587, hours before the end of her long effort to unite Britain.

“These people know more than one way to send a message, and they chose this method. You had to be very confident to make a spiral lock. If you get it wrong, you'll have to start over, which can take hours of rewriting and re-organizing. They have gone to great lengths to maintain their security," said Gana Dambrogio, lead author of a study detailing Renaissance politicians' use of this technology.

Revealing the widespread use of this method among European royalty is the latest project of a group of scientists. Their center is at the Massachusetts Institute of Technology where they shed light on a faded art they call character locking, an early form of communications security they are busy reviving.

In a detailed article published last month in the British Library's online journal, the scholars lay out the discoveries, questions, and offer examples of spiral letter-locking between queens assuming that the method "spread through European courts and through the royal correspondences".