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Abstract

A method and system is provided for generating pseudo-random numbers utilizing techniques of both the SHA-1 and DES encryption standards, wherein a pseudo-random number generator is re-keyed periodically using an external input of physical randomness. In accordance with one embodiment of the present invention, a current seed value S.sub.j is loaded from a non-volatile storage. Next, values E, representative of environmental randomness, and C, representative of configuration data are likewise loaded. A new seed value, S.sub.j+1, is generated in accordance with the equation S.sub.j+1=f (S.sub.j; A; C; E), wherein f represents a selected encryption algorithm, and B is a second constant, and wherein S.sub.j is concatenated with A, which is concatenated with C which is concatenated with E. The new seed is then written to the non-volatile storage. Next, a key, K, is generated in accordance with the equation K=f (S.sub.j; B; C; E), wherein B is a second constant. Lastly, a pseudo-random number output, P.sub.n, is generated in accordance with the equation P.sub.n=f.sub.3DES(K, P.sub.n-1), where f.sub.3DES represents the operation of triple DES encryption hardware, and P.sub.n-1 is the previously generated pseudo-random number.

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First Claim