Patent ID: 9106409
Filing Date: 2015-08-11
Classification: H04L,H04W

Abstract:
1. A method, as executed in a service control node in a communication network comprising a plurality of service points, of providing keys for protecting communication between a terminal and said service points, the method comprising: establishing a basic key for the terminal and initializing a key version parameter corresponding to the terminal, to an initial value known by the service control node and the terminal, during a registration procedure when the terminal has entered the network; creating a modified key by applying a predetermined function to at least the basic key and the initial value of the key version parameter, when the terminal starts a communication session, said modified key thereby being created in the same way as it is created by the terminal; sending the modified key to a service point to which the terminal is attached, the modified key being usable to protect communication between the terminal and the service point; after creating said modified key, updating said value of said key version by applying a predetermined scheme or algorithm to the initial value of said key version, said value of said key version thereby being updated in the same way as it is updated by the terminal; receiving a key request from a key requesting service point to which the terminal is attached; creating a new modified key by applying said predetermined function to at least the basic key and said updated value of said key version parameter, said new modified key thereby being created in the same way as it is created by the terminal; sending the new modified key to the key requesting service point, the new modified key being usable to protect communication between the terminal and the key requesting service point, and after the new modified key is created, replacing said updated value of said key version parameter with a new value determined by applying the predetermined scheme or algorithm to said updated value, said key version parameter thereby being updated in the same way as it is updated by the terminal.