Lawful Interception Triggering Control Function Split Architecture
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Solution Overview
Problem
Conventional Lawful Interception (LI) triggering methods require multiple Trusted Computing Base (TCB) entities, leading to high costs, complex security management, and inefficient data exchange, particularly due to the need for multiple connections and synchronization of target lists across network nodes.
Innovation Solution
The Triggering Control Function (TCF) is split into two entities: an LI Target List Handler (LITH) that meets security requirements for sensitive information storage and a modified TCF (mTCF) that does not, with a Generic LI Triggering Interface (GLITI) enabling communication between them to trigger interception, allowing the mTCF to interrogate the LITH for target identification without needing to meet LI security requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple TCFs are deployed to meet LI security requirements for different POI types and network traffic domains, then LI security and coverage are improved, but device complexity and costs increase
Solution Approach 1:
The TCF is segmented into two distinct functional entities: LITH (Lawful Interception Target List Handler) that handles sensitive target list data and meets LI security requirements, and mTCF (modified TCF) that performs triggering operations without requiring full TCB compliance. This segmentation allows each entity to be optimized for its specific function, reducing overall system complexity while maintaining security where needed.
Solution Approach 2:
The sensitive target list storage and management function is extracted from the TCF and placed in a separate LITH entity. This extraction removes the requirement for mTCF to maintain a trusted computing base, as only LITH needs to meet LI security requirements for holding sensitive information.
2Adaptability or versatility
If target lists are duplicated across multiple network nodes hosting TCFs, then LI coverage and availability are improved, but synchronization complexity and security risks increase
Solution Approach 1:
Multiple TCF instances are merged into a single LITH entity for target list management. Instead of duplicating target lists across multiple nodes, the centralized LITH maintains a single authoritative copy that serves all mTCF instances, eliminating synchronization complexity and security risks associated with distributed target list management.
3Measurement precision
If a complete triggering check is performed over XT and X1_1P interfaces, then triggering accuracy is improved, but processing time increases
Solution Approach 1:
A new GLITI (Generic LI Triggering Interface) is introduced as an intermediary between LITH and mTCF. This direct interface enables efficient communication for triggering operations, reducing the round-trip time compared to the conventional path through XT and X1_1P interfaces while maintaining triggering accuracy through direct LITH queries.
Data Source
AI summary
Methods and network devices implement a lawful interception (LI) trigger control function as an LI target handler and a modified trigger control function. A generic LI triggering interface enables the modified trigger control function to query the LI target handler regarding whether entities using a network function instance are in a target list. The LI target handler has to meet the LI security requirements, but the modified trigger control function does not have to meet such requirements.