Radio Network Node Handover COUNT Control Against Keystream Reuse
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Solution Overview
Problem
Keystream reuse occurs during Dual Active Protocol Stack (DAPS) handovers in 5G wireless communication networks, leading to potential exposure of confidential data due to the reuse of security keys and initialization vectors across different cells.
Innovation Solution
Maintain sequential incrementation of the DL/UL COUNT value for the Signalling Radio Bearer (SRB1) during both handover to the target cell and fallback to the source cell, ensuring that the same COUNT value is never reused, thereby preventing keystream reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If security key retention is implemented during DAPS handover to improve transmission efficiency, then re-encryption operations are reduced and processing load decreases, but keystream reuse occurs and security is compromised
Solution Approach 1:
The patent segments the COUNT value management by introducing a handover indicator that distinguishes between handover-related transmissions and regular transmissions. This allows the system to maintain security by preventing keystream reuse specifically during handover scenarios while preserving the efficiency benefits of key retention for normal operations.
Solution Approach 2:
The handover indicator acts as an intermediary mechanism between the security key retention system and the COUNT value management. It mediates the potential conflict by providing additional context that prevents keystream reuse without requiring full key changes, thus maintaining both security and efficiency.
2Reliability
If sequential incrementation of COUNT value is maintained during handover to prevent keystream reuse, then security is preserved, but additional complexity is introduced in managing sequence numbers across handover and fallback scenarios
Solution Approach 1:
The patent merges the handover management functionality into the existing COUNT value incrementation mechanism by introducing a handover indicator. This combines multiple functions (security management, handover tracking, sequence number control) into a unified approach that reduces overall system complexity while maintaining security.
Solution Approach 2:
The patent changes the parameter management approach by introducing the handover indicator as an additional parameter that modifies how COUNT values are incremented and managed. This parameter change enables the system to differentiate between handover and non-handover scenarios, simplifying the logic required to prevent keystream reuse.
3Reliability
If security parameters are updated during handover to ensure security, then keystream reuse is prevented, but processing overhead increases and handover latency increases
Solution Approach 1:
The patent applies partial action by selectively preventing keystream reuse only when the handover indicator is set, rather than always updating security parameters. This partial measure is sufficient to prevent security vulnerabilities while avoiding the performance penalty of continuous parameter updates, thus reducing handover latency.
Solution Approach 2:
The patent uses parameter changes efficiently by modifying the handover indicator parameter to control security behavior dynamically. This allows the system to maintain security only when necessary (during handover operations), minimizing processing overhead and handover latency while preventing keystream reuse.
Data Source
AI summary
Embodiments herein relate to for example a method performed by a radio network node for handling a communication of a user equipment, UE, in a wireless communication network. The radio network node transmits a handover command for handing over the UE, from a source cell to a target cell, wherein a security parameter for encrypting data communicated between the radio network node and the UE is retained during the handover. Furthermore, the radio network node maintains a sequence number status for reception and/or transmission of a signalling radio bearer of the UE during the handover from the source cell to the target cell, and/or at a fallback from the target cell to the source cell, when the UE triggers the fallback to the source cell.