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Initialization Procedure for DEA Based Pseudorandom Number Generator

IP.com Disclosure Number: IPCOM000108799D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 3 page(s) / 132K

Publishing Venue

IBM

Related People

Abraham, D: AUTHOR [+6]

Abstract

This article describes a method of generating the initial seed keys (consisting of two 128-bit data encryption algorithm (DEA) keys) used by a DEA-based pseudorandom number generator. The pseudorandom number generator is such that new seed keys are generated, or regenerated, whenever the cryptographic facility is initialized, or reinitialized, with a system master key, respectively. The seed keys themselves are derived from an internally stored master key and internal counter/ clock values sampled at indeterminate times based on independent external events not under the control of an adversary. The method is such that the work factor to cryptanalyze the seed keys is at least as great as that to cryptanalyze the system master key.

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This is the abbreviated version, containing approximately 52% of the total text.

Initialization Procedure for DEA Based Pseudorandom Number Generator

       This article describes a method of generating the initial
seed keys (consisting of two 128-bit data encryption algorithm (DEA)
keys) used by a DEA-based pseudorandom number generator.  The
pseudorandom number generator is such that new seed keys are
generated, or regenerated, whenever the cryptographic facility is
initialized, or reinitialized, with a system master key,
respectively.  The seed keys themselves are derived from an
internally stored master key and internal counter/ clock values
sampled at indeterminate times based on independent external events
not under the control of an adversary.  The method is such that the
work factor to cryptanalyze the seed keys is at least as great as
that to cryptanalyze the system master key.  However, since the seed
keys also depend on several sampled counter/clock values, it is very
unlikely that seed key values will repeat, even if the same master
key is installed, over and over, within the cryptographic facility
(e.g., following a period of maintenance when the master key has been
purposely zeroized).

      Fig. 1 illustrates a cryptographic system consisting of a
cryptographic facility (CF) 1 with a pseudo random number generator
(RNG) 6, with associated seed keys 7 (K1,K2), seed key initialization
(SKINIT) routine 8, a key storage (KS) 3, a cryptographic facility
access program (CFAP) 4, and application programs (APPLs) 5.  CFAP 4
contains a key utility program (KUP) 9 which will be invoked for key
installation of the master key and other key encrypting keys.  A
security officer starts the master key initialization process by
inserting a physical key 10 through a front panel interface 17.  KUP
9 generates an external interrupt (EXTINT) 12 to the crypto
instruction execution engine (CIEE) 2.  CIEE 2 now invokes the SKINIT
routine 8 via a request REQ 14.  This causes SKINIT 8 routine to
enter a master key initialization state. Now, CFAP 4 can execute
LFMKP (load first or intermediate master key parts) 13, or CMKP
(combine master key parts) 13 which, in turn, causes seed keys K1,K2
16 to be initialized. Once initialized, the seed keys can be used in
Random Number Generator 6 to generate pseudorandom numbers.

      Fig. 2 illustrat...