A new class of linear sequence generators based on cellular automata is here introduced in order to model several nonlinear keystream generators with practical applications in symmetric cryptography. The output sequences are written as solutions of linear difference equations, and three basic properties (period, linear complexity and number of different output sequences) are analyzed.
['Pino Caballero-Gil', 'Amparo Fúster-Sabater', 'Maria Eugenia Pazo-Robles']
Using Linear Difference Equations to Model Nonlinear Cryptographic Sequences