Communication network for encrypting/deciphering communication text while updating encryption key, a communication terminal thereof, and a communication method thereof
US6307940A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 25, 1998 |
| Grant date | Oct 23, 2001 |
| Priority date | — |
| Expiry date | Jun 25, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L2209/125
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a cryptosystem which performs encryption/deciphering of communication text using k bits of cryptographically secure pseudo-random numbers as the block cipher key thereof, the block cipher key is updated each time j=k/m bits of new pseudo-random numbers are generated, with the j.multidot.m=k bits of pseudo-random numbers created by combining the j.multidot.(m-1) bits within the k bits of the present key and the newly generated j bits, serving as a new key, thereby shortening the updating cycle and improving the safety. Also, by sending the number of times of generation of pseudo-random numbers along with the encrypted communication text from the sending side, and by the receiving side using from the sequentially generated pseudo-random numbers, pseudo-random numbers generated after the received number of times of generation as the new key, deciphering can be performed regardless of the order to reception, in the event that a plurality of cipher texts are sequentially sent while updating the encryption key.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.