5G Conditional Cell Change Security Key Derivation
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Solution Overview
Problem
In 5G mobile communications, secure transmission is a challenge when user equipment (UE) switches between primary and secondary cells, particularly due to potential key-stream reuse and security issues when switching back to the same cell or secondary node, as existing methods do not effectively manage security parameters and counter values.
Innovation Solution
The proposed solution involves deriving a security key using a counter value and a key from the master network node, where the counter value is obtained from a sequence of distinct counter values stored or generated by the processor, and using this to perform a conditional cell change procedure, ensuring secure transmission by preventing key-stream reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the UE switches back to the same PSCell or secondary node, then the cell switching functionality is achieved, but key-stream reuse occurs causing security issues
Solution Approach 1:
The patent changes the counter value parameter during cell switching operations. When the UE switches to a candidate cell, a new counter value is generated and used for security key derivation. This parameter change ensures that even when switching back to the same cell, the security key is different, preventing key-stream reuse and maintaining transmission security while preserving cell switching functionality
2Reliability
If a conditional cell change procedure is implemented, then secure transmission during cell switching is improved, but the complexity of managing counter values and security keys increases
Solution Approach 1:
The patent applies preliminary action by pre-configuring multiple candidate cells with their associated counter values before the cell switching occurs. The network node provides the UE with a list of candidate cells and corresponding counter values in advance. When switching is needed, the UE can immediately use the pre-prepared counter value for the target cell, simplifying the actual switching process while maintaining security, thus reducing the operational complexity despite the enhanced security measures
Data Source
AI summary
Examples pertaining to secure transmission in mobile communications are described. A UE receives an RRC reconfiguration message from a master network node. The RRC reconfiguration message comprises information regarding candidate cells and predefined reconfigurations, and each candidate cell is associated with one predefined reconfiguration. The UE evaluates a triggering condition for at least one candidate cell to determine whether to trigger a conditional cell change procedure and performs the conditional cell change procedure to switch a PSCell associated with the apparatus to a target cell in an event that the triggering condition for the target cell is met. The UE derives a security key according to a counter value and a key of the master network node. The counter value is obtained from a sequence of distinct counter values of the target cell or of a target secondary node stored by the processor or is generated by the processor.