Patent ID: 9094471
Filing Date: 2015-07-28
Classification: H04L,H04W

Abstract:
1. A computer-implemented method of providing, by a carrier authentication device to a user equipment, first information for generating a cipher key used for encryption, and for providing, by the carrier authentication device to an authorized intercept device, second information for generating the cipher key, wherein the authorized intercept device, the carrier authentication device, and the user equipment are distinct devices communicatively coupled to a network, the method comprising: determining a generator function that, based only on an input state value, outputs a next cipher key and a next state value, the next cipher key and the next state value being different from each other; 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, by the carrier authentication device using the generator function, the cipher key and a state value based only on the input state value; generating a first pseudo-random value based on the cipher key; transmitting, to the user equipment only during a designated time period during which lawful interception is authorized, the first pseudo-random value as the first information, wherein the user equipment generates the cipher key based on the first pseudo-random value; generating a second pseudo-random value based upon session confidentiality keys in a manner different than is used for generating the first pseudo-random value; and transmitting, to the user equipment at times other than the designated time period during which lawful interception is authorized, the second pseudo-random value as the first information, wherein the user equipment generates the cipher key based on the second pseudo-random value.