Patent ID: 7961875

Claim:
A method for ciphering and transmitting data, to be used by a communication device being arranged to transmit data through a first data port according to a first transmission protocol, and to form ciphered data by subjecting the data to a ciphering algorithm being fed with a first set of ciphering parameters, comprising a ciphering parameter CP 5 having a bit length, CP 5 BL; said device being further arranged to transmit data through a second data port according to an alternative transmission protocol, said method comprising the steps of: defining an alternative ciphering parameter, ACP, having a bit length being equal to said CP 5 BL, forming a second set of ciphering parameters by substituting said CP 5 with said ACP in said first set of ciphering parameters, forming ciphered data by subjecting the data to said ciphering algorithm being fed with said second set of ciphering parameters, transmitting said ciphered data through said second data port according to said alternative transmission protocol, and wherein said ciphering algorithm is an encryption algorithm and said first set of ciphering parameters is a first set of encryption parameters comprising a first encryption parameter, EP 1 , having a specific bit length and being a function of a parameter defined by said first transmission protocol, said device being arranged to form encrypted data by processinq the data with an encryption key bit stream, EKS 1 , formed by said encryption alqorithm being fed with said first set of encryption parameters, said method further comprisinq the steps of: defininq at least one alternative encryption parameter, AEP 1 , beinq a function of a parameter defined by said alternative transmission protocol and having a bit length being equal to a bit length of said EP 1 , forming a second set of encryption parameters by substituting said EP 1 with said AEP 1 in said first set of encryption parameters, forming an alternative encryption key bit stream, AEKS, by feeding said encryption algorithm with said second set of encryption parameters, and, encrypting the data by processing the data with said AEKS.