Method of Synthesizing Non-Linear Pseudo-Random Sequence Generator

The authors point out the expediency of using a non-linear pseudo-random binary sequences generator as a source of a key sequence in the on-line mode of encryption. They propose an algorithm for synthesizing the structure of a nonlinear pseudo-random binary sequences generator optimized for several local criteria. We consider the possibilities of reducing the cardinality of the set of non-linear functions studied by eliminating cyclic equivalent Boolean functions and choosing the class of Boolean functions called non-repeatable quadratic forms which have the best correlation characteristics. A non-repeatable quadratic form should be considered the best with respect to probability characteristics; its topology of the connection of inputs of the conjunctors with outputs of the shift register is subject to Langford's pairing. We consider the described problem as an optimization problem and it should be solved by the method of branches and boundaries.