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RANDOM NUMBER GENERATOR

IP.com Disclosure Number: IPCOM000006263D
Original Publication Date: 1991-Dec-01
Included in the Prior Art Database: 2001-Dec-19
Document File: 1 page(s) / 58K

Publishing Venue

Motorola

Related People

Douglas Allen Hardy: AUTHOR [+2]

Abstract

Many digital systems require random numbers. The repeatable nature of the digital environment renders cre- ation of truly non-deterministic numbers non-trivial. Tra- ditional methods for realizing random number sequences thus tend to have linear and predictable properties.

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MOTOROLA INC. Technical Developments Volume 14 December 1991

RANDOM NUMBER GENERATOR

by Douglas Allen Hardy and Alan Dwight Holder

  Many digital systems require random numbers. The repeatable nature of the digital environment renders cre- ation of truly non-deterministic numbers non-trivial. Tra- ditional methods for realizing random number sequences thus tend to have linear and predictable properties.

  A method for producing strings of random num- bers which are not susceptible to these weaknesses con- sists of attaching a free running counter to a clock circuit and also to a latch, as shown in Figure 1. In the present embodiment, an eleven bit latch is employed. The latching circuit stores the value which the free running counter has reached when it is stimulated by an asynchronous external input. The external input can comprise a key- stroke (press or release) or any other asynchronous event. The eleven bits are in turn passed to a maximal length linear feedback shit? register, which operates on a - 93 bit sequence to produce a pseudo-random bit stream which can be up to 10" bits in length in the present embod- iment. This bit stream is one which can be described by a set of equations if the input data are known. The bit stream is input to a nonlinear key generator circuit to produce a random number. The random number can be of arbitrary length; in most applications, between 100 and 500 bits are utilized. This result is output to external circuitry and also...