Patent ID: 6031911
Filing Date: 2000-02-29
Classification: H04L

Abstract:
A method of ciphering digital data through use of a substitution box (S-box) capable of receiving m inputs and producing n outputs, where m and n are positive integers greater than 1, comprising the steps of:(a) generating the S-box by:(i) selecting desired operational characteristics for the S-box;(ii) generating a first S-box having m inputs and having k outputs, wherein k is less than n and greater than 1;(iii) generating a column corresponding to a Boolean function of m inputs;(iv) determining the operational characteristics of a temporary S-box formed by the first S-box and the column;(v) modifying the first S-box by appending the column, if the temporary S-box possesses the desired operational characteristics;(vi) repeating steps (iii) through (v) until the first S-box has n outputs; and subsequently(b) ciphering digital data using the first S-box having the n outputs.