In 16th century, European political rulers, such as monarchs, ministers, and ambassadors used Cryptography to establish ciphers to encrypt diplomatic and/or military information. Mary, Queen of Scots was no exception where she had a cipher secretary handling her ‘secret’ correspondence in attempts to communicate with her supporters while imprisoned in England. Unfortunately for Mary, the encrypted messages were not secure enough.

 

Since the safety of Queen Elizabeth I was constantly tested from enemies at home and beyond, Elizabeth's Secretary of State, Sir Francis Walsingham created a school for espionage in London in the 1570s. There he recruited spies from Oxford and Cambridge and developing a network of agents and informants throughout Europe. From 1571 to 1586, conspiracies to overthrow Elizabeth were uncovered by Walsingham’s men. They discovered a series of plots that establish Mary’s threat to the throne which led to her trial and execution.

 

        · Ciphers

 

        · Babington plot