Cryptography – Key management – Having particular key generator
Reexamination Certificate
2005-09-20
2005-09-20
Morse, Gregory (Department: 2134)
Cryptography
Key management
Having particular key generator
C713S171000, C705S071000
Reexamination Certificate
active
06947560
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.
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Hansson Mattias
Persson Joakim
Smeets Ben
Morse Gregory
Potomac Patent Group PLLC
Telefonaktiebolaget L M Ericsson (publ)
Zia Mossadeq
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