Concealed Identifier Registration for Lawful Interception
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for lawful interception in visited public land mobile networks face challenges as they require over-the-air exchange of long-term subscriber identities, which is not feasible when networks are encrypted, and existing solutions are inoperable if the visited network refuses to register user equipment with an encrypted identifier.
Innovation Solution
A method where user equipment produces a concealed identifier and a freshness code, which are sent to the visited network, and upon receiving a permission authenticator from the home network, the user equipment transmits the long-term identifier in a non-concealed form if the authentication is verified, allowing for lawful interception while maintaining user privacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the long-term identifier is transmitted in non-concealed form to the VPLMN, then lawful interception verification is improved, but user privacy protection deteriorates
Solution Approach 1:
The system performs preliminary authentication between HPLMN and VPLMN before the UE transmits its long-term identifier. The HPLMN provides a permission authenticator to the VPLMN in advance, verifying the VPLMN's legitimacy. This preliminary action ensures that only authorized visited networks can receive the long-term identifier, thus enabling lawful interception verification while protecting user privacy through pre-validated trust relationships.
2Reliability
If the VPLMN performs authentication of the UE, then lawful interception capability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the authentication function from the VPLMN-UE interaction and relocates it to the HPLMN-UE authentication process. The HPLMN performs the cryptographic authentication with the UE using its long-term identifier, while the VPLMN only needs to verify the permission authenticator provided by the HPLMN. This extraction simplifies the VPLMN's role to basic message forwarding and verification, reducing device complexity while maintaining lawful interception capability through HPLMN-centric authentication.
3Reliability
If additional radio messages are sent to verify long-term identifier, then lawful interception verification is improved, but communication overhead increases
Solution Approach 1:
The patent merges the lawful interception verification process with the existing attach authentication procedure. The permission authenticator from HPLMN and the UE's long-term identifier are transmitted within the same uplink message (e.g., ATTACH REQUEST or EXTENDED SERVICE REQUEST) that is already part of the standard registration flow. This merging eliminates the need for separate verification radio messages, reducing communication overhead while maintaining reliable lawful interception verification through integrated authentication.
Data Source
Figure 1~4
Figure 2
AI summary
User equipment is registered with a visited public land mobile network, VPLMN, in a process including: producing at the user equipment a concealed identifier; producing at the user equipment a freshness code; and sending by the user equipment to the VPLMN the concealed identifier and the freshness code; receiving by the user equipment an identity request from the VPLMN indicating that the long-term identifier must be transmitted to the VPLMN in a non-concealed form; receiving by the user equipment from the VPLMN a permission authenticator; and verifying at the user equipment if the permission authenticator has been formed with a cryptographic authentication of the home public land mobile network, HPLMN, and the user equipment or a subscription module at the user equipment indicating permission to transmit the long-term identifier to the VPLMN in the non-concealed form and if yes, transmitting the long-term identifier to the VPLMN in the non-concealed form.