Pseudo random number e.g. secret identification number, generator for encryption of data, has linear feedback shift register and ring oscillator, where generator varies delay introduced by oscillator delay based on number of feedback bits

摘要

#CMT# #/CMT# The generator has a n-bits linear feedback shift register (LFSR) (300), and a ring oscillator (100) with a delay element (110) introducing a variable delay in a counted feedback loop. A sampling/holding device (200) has an input coupled to an output of the oscillator, and an output coupled to an input of the LFSR. A clock input receives a sampling clock signal (CLK1) at a lower frequency than the oscillator`s frequency, where the generator is configured to vary the delay introduced by the oscillator delay based on a specific number of feedback bits among the n bits of the LFSR output. #CMT# : #/CMT# An independent claim is also included for a method for generating random numbers. #CMT#USE : #/CMT# Used for generating a pseudo random number e.g. secret identification number, encryption key or initial value for an iterative encryption algorithm, for encryption of data interchanged in a secure communication system e.g. professional radiocommunication system or professional mobile radio, and in an integrated circuit. #CMT#ADVANTAGE : #/CMT# The linear feedback shift register and the oscillator are looped to each other in a random manner to guarantee a very random operation, thus permitting the random number to be deducted in the output of the linear feedback shift register at each draw having non-dependant random character, and exploiting random characteristics of physical variation such as temperature, voltage or position, of a microelectronic structure and a substrate of the circuit, and hence permitting generation of the random number with improved quality, while reducing the correlation of numbers generated with the oscillating frequency for utilizing only the oscillator randomly varying in phase and frequency. The generator permits to minimize dissipated power by limiting the number of oscillators, and dissembles a structure which only utilizes logical cells which are drowned in a set of logical gates. #CMT#DESCRIPTION OF DRAWINGS : #/CMT# The drawing shows a structure of a random number generator. CLK1 : Sampling clock signal 100 : Ring oscillator 110 : Delay element 200 : Sampling/holding device 300 : N-bits linear feedback shift register.