Method and device for effective key length control
US6947560B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 1999 |
| Grant date | Sep 20, 2005 |
| Priority date | — |
| Expiry date | Dec 15, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/0861
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
The present invention includes a method and device for calculating an encryption key, K′c, for use in the initialization of an encryption algorithm. The present invention discloses a method for calculating the encryption key, K′c(x), by obtaining a ciphering key, Kc(x), determining a maximum ciphering key length, L, based on the requirements of the two devices wishing to communicate, and determining a maximum usable encryption key length, Lmax. The ciphering key, Kc(x), is then manipulated through an addition function or an exclusively-or function with a polynomial g1(x). The result is multiplied with a polynomial g2(x), which spreads the starting points of said encryption key, K′c(x). The encryption key is thus determined according to K′c(x)=g2(L)(x)[Kc(x) mod g1(L)(x)]. The method of calculating the encryption key, K′c, ensures that a maximum ciphering key length is not exceeded. In addition, the method provides new possible starting points each time a new encryption key, K′c, is generated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.