Patent ID: 8654972
Filing Date: 2014-02-18
Classification: H04L

Abstract:
1. A stream encryption device for performing an encryption process in units of words by using a clock controller, the stream encryption device comprising: a processor; a first pseudo random number generator that generates a first pseudo random number sequence from key information; a second pseudo random number generator that generates a second pseudo random number sequence based on clock control performed by the clock controller in accordance with the first pseudo random number sequence; a nonlinear function operator; a keystream generator that generates a keystream by receiving the second pseudo random number sequence as an input and by applying a nonlinear function calculation using the nonlinear function operator to the second pseudo random number sequence; and an encrypter that generates an encrypted text by performing exclusive OR operation over the generated keystream and plain text and an internal memory which is updated according to data resulting from an arithmetic addition or exclusive OR operation performed over the keystream and the first or second pseudo random number sequence, and which provides the data, as an input data together with the second pseudo random number sequence, to the keystram generator; wherein the clock controller controls the second pseudo random number generator based on clock control by using a root α of a polynomial which defines a finite field of degree 2, which is used to generate the second pseudo random number, and by multiplying α^n in a bit shift operation of feedback polynomial or characteristic polynomial in a linear feedback shift register included in the second pseudo random number generator, where n represents a number of clocks determined by the clock controller.