IMS Authentication Using Digest Algorithm for Legacy Terminals

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Solution Overview

Problem

Conventional user equipment incapable of supporting IP multimedia subsystem (IMS) Authentication Key Agreement (AKA) faces challenges in authenticating securely across different access environments, limiting compatibility and security in IMS networks.

Innovation Solution

Implementing a Digest Authentication method, specifically using algorithms like Digest MD5 or MD5-sess, where the Serving-Call Session Control Function (S-CSCF) generates an authentication challenge, and the user equipment responds with a calculated authentication response, verified by the S-CSCF and Home Subscriber Server (HSS) to ensure secure access in various environments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If IMS AKA mechanism is used for authentication, then security is improved, but compatibility with conventional user equipment deteriorates

Engineering Contradiction:
Improveauthentication securityVSAvoidequipment compatibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent changes the authentication parameter from IMS AKA to Digest authentication algorithm, allowing conventional user equipment to be authenticated. The S-CSCF entity obtains authentication parameters from HSS and uses Digest MD5 or MD5-sess algorithm to verify user equipment, maintaining security while improving compatibility.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The S-CSCF entity acts as an intermediary between the HSS and conventional user equipment. It obtains authentication parameters from HSS, generates authentication challenges, and verifies responses using Digest authentication, enabling secure authentication without requiring HSS to directly support Digest authentication.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Adaptability or versatility

If Digest Authentication is implemented for conventional user equipment, then compatibility is improved, but authentication complexity increases

Engineering Contradiction:
Improveequipment compatibilityVSAvoidauthentication process complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The S-CSCF entity automatically obtains authentication parameters from HSS and performs Digest authentication verification without manual intervention. The system self-manages the authentication process, reducing operational complexity despite the increased procedural steps.

Inventive Principle:
Principle #25Self-service

3Reliability

If authentication parameters are obtained from HSS, then authentication reliability is improved, but signaling interaction overhead increases

Engineering Contradiction:
Improveauthentication reliabilityVSAvoidsignaling message quantity
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The S-CSCF entity obtains authentication parameters from HSS in advance, before actual authentication is needed. This preliminary action allows the parameters to be cached and reused for multiple authentication challenges, reducing the frequency of HSS interactions and minimizing signaling overhead.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP1879324B1A method for authenticating user terminal in IP multimedia sub-system
Publication Date: 2012.08.01 HUAWEI TECH CO LTD
  • EP1879324B1 patent drawingFigure 1
  • EP1879324B1 patent drawingFigure 2
  • EP1879324B1 patent drawingFigure 3

AI summary

A method for authenticating user terminal in IMS network, the method includes: with regard to user request, Service-Call Session Control Function(S-CSCF) entity creates the authentication challenge utilizing Digest Authentication Algorithm, and sends the authentication challenge to user terminal through Proxy- Call Session Control Function(P-CSCF) entity; the user terminal creates the authentication response utilizing Digest Authentication Algorithm according to the user key and associated parameters with said authentication challenge, and sends the authentication response to S-CSCF entity through S-CSCF entity; S-CSCF entity authenticates said authentication response utilizing Digest Authentication Algorithm according to HAI and associated parameters, if the authentication passes, determines that the user terminal is authenticated successfully, otherwise, determines that the user terminal is authenticated failure.