A Cypher is an English weapon that is used for translating secret messages.
Anyone in France who is found in possession of one would be immediately executed as a traitor for high treason agent the crown.
The last know owner of one of these was Armsman, Richard Gifford who was communicating with The English Crown, Queen Elizabeth agents the French.
It was later found in his chambers by Queen Catherine's spies. She had since made copies of it, and gave the original to her son King Francis. 
Francis later put it in an envelope and instructed Lady Lola to hide it in Stéphane Narcisse' house. Soon after she left, Lord Narcisse found the envelope and destroyed it.
Days later, the Royal Guards arrived at Lord Narcisse's house with a warrant looking for any evidence against him, on counts of conspiring against the Crown. Hours later, they left empty handed. 
The Cypher was once again used by King Francis and Queen Mary after recieving a letter from Queen Mary's mother, Marie de Guise.