Félix Delastelle

Félix-Marie Delastelle was a French amateur cryptographer best known for a family of fractionating ciphers. His Bifid and Trifid designs use coordinate representations of letters and recombination across a block of text.

New cryptography

Delastelle introduced his ideas as cryptographie nouvelle in the 1890s and later gathered his work in Traité Élémentaire de Cryptographie. The Bifid cipher is especially notable for combining substitution and transposition in one procedure.

Historical significance

His work gives students of cryptography a concrete view of how diffusion-like behavior can arise in hand ciphers, before modern formal terminology and electronic computation.

In memoriam

Delastelle died in 1902, shortly after completing his treatise. His cipher designs remain studied as milestones in classical cryptography.

Timeline

• 1840-01-02Born in France.
• 1895Presents “cryptographie nouvelle,” associated with the Bifid approach.
• 1901Completes Traité Élémentaire de Cryptographie.
• 1902-04-02Dies in France.