Anti-spoof without error extension (ANSWER)
US5734721A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 12, 1995 |
| Grant date | Mar 31, 1998 |
| Priority date | — |
| Expiry date | Oct 12, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/0662
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
There is disclosed encryption apparatus for generating a deterministic psuedorandom keystream of data derived from a secret key and a prearranged initial state and modulo-N adding the random data to plain text data to form a cipher text data stream to be transmitted. In order to reduce spoofing, which is the ability to alter received plain text by altering the transmitted cipher text there is means responsive to the plain text for altering a portion of the plain text data relative to corresponding cipher text data according to a permutation function which varies according to a selected keystream whereby one who does not possess said secret key cannot decrypt said cipher text and while preventing spoofing.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.