| Cryptographie indéchiffrable | |
| Author: | Émile Victor Théodore Myszkowski |
| Language: | French |
| Genre: | Factual |
| Pub Date: | 1902 |
Cryptographie indéchiffrable (subtitle: basée sur de nouvelles combinaisons rationelles) is a French book on cryptography written by Émile Victor Théodore Myszkowski (a retired French colonel) and published in 1902.
His book described a cipher that the author had invented and claimed (incorrectly) was "undecipherable" (i.e. secure against unauthorised attempts to read it). It was based on a form of repeated-key transposition.