Block cipher system for data security
US3958081A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 24, 1975 |
| Grant date | May 18, 1976 |
| Priority date | — |
| Expiry date | Feb 24, 1995 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2209/24
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A device for ciphering message blocks of data bits under control of a cipher key. The cipher device performs an enciphering process for each message block of data by carrying out a predetermined number of iteration operations in the first of which a first half of the message block of data bits is first expanded by duplicating predetermined ones of the data bits. The data bits of the expanded message block are combined by modulo-2 addition with an equal number of cipher key bits, selected in accordance with an arbitrary but fixed permutation, to produce a plurality of multi-bit segments forming the arguments for a plurality of different nonlinear substitution function boxes. The substitution boxes perform a plurality of nonlinear transformation functions to produce a substitution set of bits which are equal in number to the number of data bits in the first half of the message block. The substitution set of bits is then subjected to a linear transformation in accordance with an arbitrary but fixed permutation. The combined nonlinear transformation and linear transformation results in a product block cipher of the first half of the message block. The second half of the message block i…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.