NONLINEAR QUANTIZATION PROCESSING METHOD FOR TIME SERIES OF CHAOS

摘要

PROBLEM TO BE SOLVED: To strengthen the stiffness of ciphering by conducting nonlinear quantization at unequal intervals so that ununiform distribution is a uniform distribution. ;SOLUTION: A total number of internal states y(t) calculated or actually measured linearly, that is, a maximum value of a discrete time (t) is selected to be t_max=2²⁰=1048576, then data are again quantized into 8-bits (2⁸=256) nonlinearly to obtain a uniform distribution. Then a time series y(t)-1 calculated or measured linearly is retrieved. A minimum internal state y(t) is found out sequentially through the retrieval along the discrete time (t) and pieces of '0' are assigned up to the 4096-th y(t) from the beginning. Pieces of '1' are assigned to succeeding 4096 sets of y(t) and pieces of 255 are assigned to final 4096-sets of y(t). Then the time series y(t)-1 calculated or actually measured linearly is again assigned to an 8-bit (0 to 255) new quantization space (grating) Y(t) so that 4096-sets are uniformly distributed in each quantized Y(t).;COPYRIGHT: (C)1998,JPO