Cell-Specific Security Key Updates to Prevent PSCell Key Reuse
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Solution Overview
Problem
The reuse of the same security key KSN for multiple subsequent Conditional PSCell changes in wireless communication systems reduces the security of data transmission due to the same key being used to encrypt different data packets.
Innovation Solution
A method for determining a security key corresponding to a candidate cell or cell group based on a first criterion, involving a terminal or network device, which includes updating a counter to generate a new security key for each candidate cell or cell group change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the same SK-counter stored in CPC configuration is used for multiple subsequent CPCs on the same candidate PSCell, then the device complexity is reduced and operation is simplified, but the security of data transmission deteriorates due to reuse of the same security key KSN
Solution Approach 1:
The patent applies the dynamics principle by making the security key generation process adaptive and variable. Instead of using a static SK-counter value for multiple CPCs, the system dynamically updates the security key by incorporating a unique identifier (such as a cell ID or PSCell identifier) into the key derivation function. This ensures that each CPC operation on the same candidate PSCell generates a different security key, preventing key reuse while maintaining operational simplicity through automated key derivation.
Solution Approach 2:
The patent applies the local quality principle by introducing cell-specific or PSCell-specific parameters into the security key derivation process. The unique identifier associated with each candidate PSCell is incorporated into the key generation formula, ensuring that the security key is locally adapted to each specific cell context. This means that even though the SK-counter may remain the same, the resulting security key differs for each PSCell, thereby enhancing security without complicating the overall system operation.
2Reliability
If a counter is updated for each candidate cell or cell group change to generate a new security key, then the security of data transmission is improved by preventing key reuse, but the device complexity increases
Solution Approach 1:
The patent applies the self-service principle by enabling the terminal to autonomously derive and update security keys without requiring complex external management. The terminal uses locally available information (such as cell identifiers and existing counter values) to self-generate updated security keys through a standardized derivation function. This self-service approach ensures enhanced security through key updates while avoiding the need for complex external key management infrastructure, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent applies the parameter changes principle by modifying the input parameters of the security key derivation function in a controlled and systematic way. Instead of completely redesigning the key management system, the patent changes specific parameters (such as incorporating cell-specific identifiers or updating counter values) within the existing key derivation framework. This approach achieves improved security through parameter variation while leveraging existing system structures, thereby minimizing the increase in device complexity.
Data Source
AI summary
A method for security key update, performed by a terminal or network device, includes: determining a security key corresponding to a candidate cell or cell group according to a first criterion. Determining the security key includes updating a first counter according to the first criterion, wherein the first counter is configured to determine the security key corresponding to the candidate cell or cell group and determining the security key corresponding to the candidate cell or cell group according to the first counter.