DES encryption and decryption unit with error checking
US5432848A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 15, 1994 |
| Grant date | Jul 11, 1995 |
| Priority date | — |
| Expiry date | Apr 15, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2209/34
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
An improved DES unit internally checks whether the DES algorithm is being performed without error. A standard DES algorithm performs an initial permutation of input data and then multiple rounds or iterations of the following: expanding part of a result of the initial permutation for the first iteration and a result of the previous iteration for the subsequent iterations, exclusive ORing a result of the expansion with key bits, performing a selection function on a result of the exclusive ORing, permuting a result of the selection function, and exclusive ORing a result of the permuting. In the improved DES unit, data check bits that correspond to the input data which has been expanded are exclusive NORed with key check bits that correspond to the key, and a result of the exclusive NORing is checked against a result of the exclusive ORing to identify any errors in the operation of the basic DES unit. Also, a check selection function is performed on the result of the exclusive ORing. A result of the check selection function is exclusive NORed with data check bits for another part of the input data to yield input data for input to the expanding function for a next iteration. Also, the …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.