IMS Subscriber Registration Using GUTI-Derived Temporary Identities
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Solution Overview
Problem
Current methods for registering a User Equipment (UE) in an IP Multimedia Subsystem (IMS) do not protect the Subscriber Permanent Identifier (SUPI), such as the International Mobile Subscriber Identifier (IMSI), over a radio access network, and encryption on the user plane may not be enabled in all networks.
Innovation Solution
Generate Temporary IMS Private User Identity (TIMPI) and Temporary IMS Public User Identity (TIMPU) from a Globally Unique Temporary Identifier (GUTI) to temporarily identify the UE, allowing IMS registration without sending the IMPI or IMSI in clear over the radio access network, using the TIMPI and TIMPU to determine the IMSI through network communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current IMS registration procedures are used, then registration can be completed, but the IMSI is sent in clear over the radio access network which compromises security
Solution Approach 1:
The patent introduces temporary identities (TIMPI and TIMPU) as intermediary elements between the UE and IMS network. These temporary identifiers act as mediators that allow registration to proceed while preventing the exposure of the permanent IMSI over the radio interface, thus resolving the contradiction between security and operational simplicity
Solution Approach 2:
The patent segments the identity information into temporary and permanent components. The temporary identities (derived from GUTI) are used for radio access and initial registration, while the permanent IMSI is protected and only used in secure contexts. This segmentation allows the system to maintain both security and ease of operation
2Reliability
If encryption over the user plane is implemented, then security is improved, but it cannot be enabled in all networks reducing adaptability
Solution Approach 1:
The temporary identities serve as intermediaries that provide security without requiring encryption infrastructure. By using TIMPI/TIMPU instead of IMSI over the radio interface, the system achieves security through identity protection rather than cryptographic protection, enabling deployment in networks regardless of their encryption capabilities
Solution Approach 2:
The patent changes the parameter being transmitted over the radio interface from permanent (IMSI) to temporary (GUTI-derived identifiers). This parameter change allows the same registration procedure to work securely in both encrypted and non-encrypted networks, improving adaptability while maintaining security
Data Source
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AI summary
A method of registering a subscriber in an IP Multimedia Subsystem (IMS), said subscriber being associated with an IMS Private User Identity (IMPI) and an IMS Public User Identity (IMPU) and further being associated with a 4G or 5G conforming User Equipment (UE). The method comprises: at the UE, generating a Temporary IMS Private User Identity (TIMPI) and a Temporary IMS Public User Identity (TIMPU) from a Globally Unique Temporary Identifier (GUTI) allocated by and received from a 4G or G network to temporarily identify the UE; sending an IMS registration request containing the TIMPI and the TIMPU from the UE to the IMS; at the IMS, using the TIMPI and the TIMPU to determine the GUTI, and communicating with the 4G or 5G network to determine, using the GUTI, an International Mobile Subscriber Identifier (IMSI) associated with the UE; at the IMS, using the IMSI to determine said IMPI and IMPU; and completing IMS registration of the subscriber using the IMPI and the IMPU.