Patent ID: 6285761
Filing Date: 2001-09-04
Classification: G06F,H04L

Abstract:
A method of providing message encryption using an output of a pseudo-random number generator wherein the pseudo-random number generator is defined by a modular exponential function x.sub.i =g.sup.x.sup..sub.i-1 mod p, where x.sub.i is a value comprising m bits, p is a prime number comprising k bits, g is a generator of integer mod p, and 1<i .ltoreq.n, and wherein m and k are selected to achieve a desired security threshold level c, and m is further selected to cause the difference term m-2c to be greater than log.sub.2 m+1, the method comprising the steps of:receiving a seed value x.sub.0 for the pseudo-random number generator;generating a value x.sub.i, using the pseudo-random number generator, wherein an initial value of the x.sub.i-1 term for the generator is the seed value x.sub.0 ;outputting from the generator a pseudo-random number z.sub.i constituted as j-1 bits of the generated value x.sub.i, the pseudo-random number z.sub.i including a second least significant bit of the value x.sub.i and excluding a least significant bit of the value x.sub.i, the value j being greater than log.sub.2 m and no larger than m-2c; andcombining the pseudo-random number z.sub.i with a message segment to produce an encrypted message segment.