Patent ID: 8335487

Claim:
A method for authenticating a user equipment in an IP multimedia subsystem, comprising: generating, by a Serving-Call Session Control Function (S-CSCF) entity, an authentication challenge through a Digest Authentication Algorithm in response to a subscriber request, and sending the authentication challenge to the user equipment through a Proxy-Call Session Control Function (P-CSCF) entity; receiving, by the user equipment, the authentication challenge; generating, by the user equipment, an authentication response through the Digest Authentication Algorithm in accordance with a subscriber key and the authentication challenge, and sending the authentication response to the S-CSCF entity through the P-CSCF entity; receiving, by the S-CSCF entity, the authentication response; and verifying, by the S-CSCF entity, the authentication response through the Digest Authentication Algorithm in accordance with information HA 1 related to the subscriber key and the authentication response, and if the verification is passed, determining that the authentication for the user equipment succeeds, otherwise determining that the authentication for the user equipment fails, wherein the Digest Authentication Algorithm includes a Digest MD5 algorithm, and the S-CSCF entity obtains the HA 1 through interacting with a Home Subscriber Server (HSS) before generating the authentication challenge or upon receiving the authentication response, wherein the obtaining the HA 1 comprises: sending, by the S-CSCF entity, to the HSS a request message carrying a subscriber identity; and generating, by the HSS, the HA 1 in accordance with a domain name of a domain corresponding to the subscriber, the subscriber identity and the subscriber key, and returning to the S-CSCF entity the HA 1 in a response message.