Blaise de Vigenère (April 5, 1523 - 1596) was a French diplomat and cryptographer. The Vigenère cipher is so named due to the cipher being incorrectly attributed to him in the 19th century.

Vigenère (IPA:"veez-ih-nair") was born in the village of Saint-Pourçain. At age 17 he entered the diplomatic service, and remained there for 30 years, retiring in 1570. Five years into his career he was sent to the Diet of Worms as a very junior secretary. At age 24, he entered the service of the Duke of Nevers. In 1549 he visited Rome on a two-year diplomatic mission, and again in 1566. On both trips, he came in contact both with books on cryptography and cryptologists themselves. When Vigenère retired aged 47, he donated his 1,000 livres a year income to the poor in Paris. He married a Marie Varé.

In his retirement, he was author of over twenty books including,

• Traicté de Cometes
• Traicté de Chiffres (1585)
• Traicté du Feu et du Sel (1608)

In Traicté de Chiffres he described an autokey cipher he had invented, it was the first cipher of this type not to be trivially breakable.

Vigenère died of throat cancer in 1596.