The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 27, 1990
Filed:
Oct. 28, 1988
Raymond A Schulz, Manassas, VA (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A very large scale integrated (VLSI) compatible, random number generator which is highly invulnerable to cryptographic attack. The invulnerability to cryptographic attack is based upon a low frequency sampling of the output of a pseudo-random number generator which is operated at a varying frequency from a free-running ring oscillator. In a first embodiment, a free-running ring oscillator is used to drive a sampled linear feedback shift register. The asynchronous, serial pseudo-random number output from the linear feedback shift register is sampled periodically, thereby introducing randomly occurring deviations from the pseudo-random number sequence. A variation of the free-running ring oscillator is employed as the pseudo-random number generator, by introducing into the feedback loop of the ring oscillator, an exclusive OR circuit which is connected so that the ring oscillator thereby produces a serial, pseudo-random number sequence. Additional uncertainty in the sequence of random numbers produced by the free-running pseudo-random number generator, is caused by the race condition which occurs at the inputs to the exclusive OR connected in the circuit.