RRC Key Change Activation in LTE-Active Mode
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Solution Overview
Problem
The existing 3G mobile communication systems lack a clear method for performing key updates in LTE-Active mode, specifically in RRC_CONNECTED or LTE_ACTIVE states, particularly in determining whether a key change is accompanied by an Authentication and Key Agreement (AKA) run, which is crucial for ensuring data security and managing key hierarchies effectively.
Innovation Solution
The method employs an RRC procedure to activate key changes, determining whether the change is with or without an AKA run by using an indicator in RRC messages, and derives new Access Stratum keys accordingly from either the new or previous base keys based on the AKA run status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If key change is performed without AKA run in LTE_ACTIVE mode, then key update efficiency is improved, but data security may be compromised
Solution Approach 1:
The patent segments key update procedures into two distinct paths: one with AKA run and one without AKA run. The segmentation is based on whether the UE is in LTE_IDLE or LTE_ACTIVE mode, allowing efficient key updates without AKA for active mode while maintaining security through proper key derivation relationships.
Solution Approach 2:
The patent performs preliminary key derivation by establishing the relationship between KeNB and KASME before actual key updates. This preliminary action ensures that even when AKA is not executed, the key derivation maintains security guarantees through pre-established cryptographic relationships.
2Reliability
If AKA run is performed for every key change, then data security is ensured, but signaling overhead and processing time increase
Solution Approach 1:
The patent divides key update scenarios into segments where AKA run is required (LTE_IDLE mode) and where it is not required (LTE_ACTIVE mode). This segmentation eliminates unnecessary AKA executions while maintaining security through the established key derivation framework.
Solution Approach 2:
The patent applies partial action by performing only the necessary key derivation steps without executing the full AKA protocol when the UE is already in LTE_ACTIVE mode. This partial approach maintains adequate security while reducing processing time and signaling overhead.
3Productivity
If key hierarchy is simplified for faster updates, then update speed is improved, but security management complexity increases
Solution Approach 1:
The patent segments the key hierarchy management into mode-specific procedures, where LTE_IDLE and LTE_ACTIVE modes have different key update pathways. This segmentation simplifies the actual update process while maintaining comprehensive security management through clear procedural distinctions.
Solution Approach 2:
The patent implements dynamic key management where the key update procedure adapts based on the UE's operational mode. The system dynamically selects between AKA-based and non-ACK-based key updates, providing both speed and security through context-aware procedure selection.
Data Source
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AI summary
A method of handling security key change for a user equipment in a wireless communication system (10) includes applying a radio resource control procedure to activate key change, where the radio resource control procedure covers two conditions where the key change is accompanied with an authentication and key agreement run and without an authentication and key agreement run.