The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 20, 2005
Filed:
Dec. 15, 1999
Ben Smeets, Dalby, SE;
Mattias Hansson, Lund, SE;
Joakim Persson, Lund, SE;
Telefonaktiebolaget L M Ericsson (publ), Stockholm, SE;
Abstract
The present invention includes a method and device for calculating an encryption key, K', for use in the initialization of an encryption algorithm. The present invention discloses a method for calculating the encryption key, K′(x), by obtaining a ciphering key, K(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, L. The ciphering key, K(x), is then manipulated through an addition function or an exclusively-or function with a polynomial g(x). The result is multiplied with a polynomial g(x), which spreads the starting points of said encryption key, K′(x). The encryption key is thus determined according to K′(x)=g(x)[K(x) mod g(x)]. The method of calculating the encryption key, K′, 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′, is generated.