| 摘要 |
PROBLEM TO BE SOLVED: To generate pseudo-random numbers having high resistance to correlation attack in a comparatively simple circuit constitution by thinning the clocks to be inputted to a linear (nonlinear) feedback shift register which generates the pseudo random numbers. SOLUTION: Bit series held by a shift register 801 are supplied to an output terminal 813 and a nonlinear function circuit 803. An exclusive OR circuit 802 calculates the exclusive OR of the bit of a prescribed position among the bit series held by the register 801 and supplies this calculation result to the register 801. Then the circuit 803 calculates the nonlinear connection of the bit of a prescribed position among the bit series held by the register 801, and this calculation result is outputted as a pseudo random number via an output terminal 814. In such a constitution, it's possible to generate the pseudo random numbers suitable for the stream ciphering without increasing the number of stages and pieces of shift registers and by thinning the clock pulses even when a pseudo random number generator consists of a nonlinear feedback register. |
