Patent ID: 11877150
Assignee: HUAWEI TECHNOLOGIES CO., LTD.
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A communication system, comprising:
a target mobility management network element; including at least one first processor configured to: receive a first initial non-access stratum (NAS) message from a terminal, wherein the first initial NAS message comprises a first non-cleartext information element that is security protected by using a first root key, and send the first initial NAS message to a source mobility management network element; and
the source mobility management network element including at least one second processor configured to: after performing an integrity check on the first initial NAS message, update the first root key stored by the source mobility management network element, to generate a second root key, and send first indication information and the second root key to the target mobility management network element, wherein the first indication information indicates that the second root key is obtained by updating the first root key, wherein
the target mobility management network element is further configured to send second indication information and third indication information to the terminal based on the first indication information, wherein the second indication information indicates the terminal to update the first root key stored by the terminal to obtain the second root key, the third indication information indicates the terminal to send a second initial NAS message, the second initial NAS message comprises a second non-cleartext information element that is security protected by using the second root key, and content of the second non-cleartext information element is the same as that of the first non-cleartext information element.