METHOD OF LAWFUL INTERCEPTION FOR UMTS

A method of providing, to a user equipment, first information for generating a cipher key used for encryption, and for providing, to an authorized intercept device, second information for generating the cipher key, the method including determining a generator function that, based on an input state value, outputs a next cipher key and a next state value, determining an initial state value for the generator function, providing, to the authorized intercept device, the generator function and the initial state value as the second information, generating the cipher key and a state value based on the function generator and the input state value, generating a pseudo-random value based on the cipher key, and transmitting, to the user equipment, the pseudo-random value as the first information, wherein the user equipment generates the cipher key based on the pseudo-random value.