Lightweight word-oriented technique for generating a pseudo-random sequence for use in a keystream of a stream cipher
US6490354B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 23, 1998 |
| Grant date | Dec 3, 2002 |
| Priority date | — |
| Expiry date | Jun 23, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/0662
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A word-oriented technique for generating a pseudo-random sequence, e.g., a keystream (17) for use in a stream cipher. Specifically, the technique utilizes two different arrays (653, 657) with each array having illustratively 256 32-bit elements. One array (653) contains a 256 element 32-bit S-box. An output stream generated by the S-box, i.e., St, is applied as one input to a first hash function. This hash function, in response to input St multiplied by a variable, C, provides the output keystream. S-box element St is then updated through a second hash function having, as its input, the current value of St multiplied by the variable C. The variable, C, initially a random variable, is itself updated, for use during a next iteration, through an additive combination, of its current value and a corresponding element in the second array (G), i.e., Gt. Both the S-box and G array can be initialized by, e.g., entirely filling each of these arrays with random 32-bit values. This technique, when used to generate a keystream for a stream cipher, appears to be just as secure as a conventional RC4 cipher and, by operating on a word- rather than a byte-level, is considerably faster than an RC4 k…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.