Non-Triangular Self-Synchronizing Stream Ciphers

In this paper, we propose an instantiation, called \textsf{Stanislas}, of a dedicated Self-Synchronizing Stream Cipher (SSSC) involving an automaton with finite input memory using non-triangular state transition functions. Previous existing SSSC are based on automata with shifts or triangular functions (T--functions) as state transition functions. Our algorithm \textsf{Stanislas} admits a matrix representation deduced from a general and systematic methodology called Linear Parameter Varying (LPV). This particular representation comes from the automatic theory and from a special property of dynamical systems called flatness.