Roger Frontenac was a French navy officer and a scholar of Nostradamus' prophecies. He proposed an interpretation system for the text of Les Propheties, based upon a form of cryptography known as the Vigenère table. Roger Frontenac, as a navy officer, was in charge of military cyphers. After World War II, he began to study the work of Nostradamus, treating it as any other message from an enemy. He searched for any hint about decoding methods. The name of Nostradamus' son Cesar led Frontenac to suspect the use of a Caesar cypher. In 1950 he published his treatise about Nostradamus' letters and works, La clef secrète de Nostradamus (The Secret Key of Nostradamus). In the book, Frontenac professed his belief in Nostradamus as a true prophet, who made correct foretellings, and that the centuries (in French Les Propheties) contained true predictions about future events until the year 3797.