Cryptography – Particular algorithmic function encoding
Patent
1997-03-31
1998-11-10
Gregory, Bernarr E.
Cryptography
Particular algorithmic function encoding
380 9, 380 29, 380 30, 380 33, 380 46, 380 49, 380 50, H04L 900
Patent
active
058355979
ABSTRACT:
A software-efficient pseudorandom function maps an index and an encryption key to a pseudorandom bit string useful for constructing a stream cipher. The method begins by preprocessing the encryption key into a table of pseudorandom values. The index and a set of values from the table is then used to generate a set of initial values for the registers. At least some of the register values are modified in part by taking a current value of a register and replacing the current value with a function of the current value and a value retrieved from the table, the latter value being determined by the values in one or more other registers. After modifying the register values in this fashion, the values are masked using other values from the table and the results then concatenated into the pseudorandom bit string. The modification step is repeated and a new masked function of the register values is then concatenated into the pseudorandom bit string. The modification and concatenation steps are repeated to continue growing the pseudorandom bit string until the string reaches some desired length.
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Coppersmith Don
Rogaway Phillip W.
Gregory Bernarr E.
International Business Machines - Corporation
Judson David H.
LaBaw Jeffrey S.
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