Félix Delastelle, Date of Birth, Date of Death
TweetFélix Delastelle
French cryptographer (1840–1902)
Date of Birth: 
About Félix Delastelle
- Félix-Marie Delastelle (2 January 1840–2 April 1902) was a French cryptographer, best known for inventing the bifid cipher, first presented in the Revue du Génie civil in 1895 under the name of "cryptographie nouvelle".
- This cipher combines fractionation with transposition, and was an early cipher to implement the principles of confusion and diffusion.
- David Kahn described it as a "system of considerable importance in cryptology."Delastelle's other polygraphic substitution ciphers included the trifid and four-square ciphers The last of these is a variant on the earlier Playfair cipher: Delastelle may have been unaware of Playfair, but he had certainly read of the fractionating cipher described by Pliny Chase in 1859. There are few biographical details.
- Félix-Marie's father, a master mariner, was lost at sea in 1843.
- Félix attended the College of Saint-Malo until 1860.
- After leaving school, he worked in the local port, as a bonded warehouseman, for forty years, and pursued his interest in amateur cryptography as a hobby. Following his retirement in 1900, he rented a single room in a holiday hotel where he wrote a 150 page book Traité Élémentaire de Cryptographie which he completed in May 1901.
- On hearing news of his brother's sudden death, he collapsed and died in April 1902.
- His book appeared three months later, published by Gauthier-Villars of Paris. Delastelle is unusual for being an amateur cryptographer at a time when significant contributions to the subject were made by professional soldiers, diplomats and academics.
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