RAN Node Key Refresh for Mobile Security
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Solution Overview
Problem
Current security solutions for wireless communication networks, particularly in LTE and emerging 5G and NR contexts, face challenges in balancing security needs with computational efficiency, as they often require frequent key changes that incur unnecessary signaling and processing overhead, while infrequent changes may jeopardize network security.
Innovation Solution
A method is introduced where a wireless device transitions from a connected RRC state to an inactive state, maintaining key material connections with the RAN and CN nodes, and requests new key material upon returning to the connected state, allowing for strategic key replacement without frequent unnecessary changes, thereby balancing security and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent key changes are implemented to enhance security, then network security is improved, but signaling overhead and processing overhead increase
Solution Approach 1:
The patent implements periodic key refreshment based on timer expiration or specific triggering events (handover, state transition) rather than continuous key changes. This periodic approach maintains security by updating keys at appropriate intervals while avoiding unnecessary processing overhead from excessive key changes.
Solution Approach 2:
The key refreshment mechanism is made dynamic by triggering key updates based on specific conditions (handover events, state transitions between RRC_IDLE and RRC_CONNECTED, timer expirations) rather than following a fixed schedule. This allows the system to adapt key refresh timing to actual network conditions and security needs.
2Reliability
If frequent key changes are implemented to enhance security, then network security is improved, but signaling overhead increases
Solution Approach 1:
The system performs key refreshment periodically based on timer expiration or specific triggering events rather than continuously, which reduces the number of signaling messages required for key management while maintaining security through regular key updates.
Solution Approach 2:
The network pre-generates and stores multiple key material sets (K_NH1, K_NH2, etc.) before they are needed. When a key refresh is triggered, the system can quickly switch to pre-prepared key material without requiring extensive real-time key generation signaling, thereby reducing signaling overhead.
3Productivity
If key material is maintained during inactive state to reduce overhead, then processing efficiency is improved, but security risk increases due to prolonged key usage
Solution Approach 1:
The system uses timer-based mechanisms to periodically refresh key material even during inactive states. This ensures that keys do not remain valid indefinitely, mitigating security risks from prolonged key usage while avoiding the overhead of more frequent key changes. The timer expiration triggers selective key refreshment only when necessary.
Solution Approach 2:
The system changes the validity parameters of key material by introducing timer-based expiration mechanisms and event-triggered refresh conditions. This allows the key lifecycle to be dynamically managed, balancing security requirements with processing efficiency by adjusting key validity periods based on operational context.
4Reliability
If key material is updated frequently to mitigate security risks, then security is improved, but unnecessary signaling overhead occurs
Solution Approach 1:
The system implements periodic key updates triggered by specific events (handover, state transitions, timer expiration) rather than continuous updates. This approach maintains security by refreshing keys at appropriate intervals while minimizing unnecessary signaling overhead from excessive key management messages.
Solution Approach 2:
The system autonomously manages key material by pre-generating and storing multiple key sets locally. When a refresh is needed, the system can self-select and switch to pre-prepared key material without requiring extensive real-time communication with the network, thereby reducing signaling overhead while maintaining security.
Data Source
AI summary
A Radio Access Network (RAN) node instructs a wireless device having a connection to the RAN node to transition from a connected Radio Resource Control (RRC) state to an inactive RRC state in which key information supporting the connection, and a further connection to a Core Network (CN) node serving the wireless device, are maintained. Responsive to the wireless device returning to the connected RRC state, the RAN node requests new key material from the CN node, and replaces the key material supporting the connection with the new key material received from the CN node.