Groupcast L2 Identifier Hashing to Prevent UE Tracking
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Solution Overview
Problem
Existing privacy protection mechanisms for Layer 2 (L2) identifiers in 5G groupcast communication are inadequate, as they do not effectively prevent attackers from tracking UEs based on fixed destination L2 identifiers, which can reveal group membership.
Innovation Solution
A cryptographic security mechanism that generates pseudorandom destination L2 identifiers by hashing and converting group and source identifiers, ensuring that the same identifier is not reused, thereby enhancing privacy by making it difficult for attackers to track UE membership.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fixed destination L2 identifiers are used for groupcast communication, then communication efficiency is improved, but privacy protection deteriorates as attackers can track UEs based on these identifiers
Solution Approach 1:
The patent applies dynamics by making the destination L2 identifier changeable rather than fixed. The identifier is dynamically generated based on the source L2 identifier and a group-specific seed, ensuring that each UE using the same group identifier generates a unique destination identifier. This dynamic approach maintains communication efficiency while preventing tracking, as the identifier changes with each source UE even within the same group.
Solution Approach 2:
The patent changes the parameter of the destination L2 identifier from a fixed group-specific value to a dynamically generated value that depends on both the source L2 identifier and a group-specific seed. This parameter change ensures that the destination identifier is unique to each source UE within a group, preventing attackers from tracking UEs while maintaining efficient groupcast communication.
2Object-affected harmful factors
If source L2 identifiers are changed regularly to protect privacy, then tracking resistance is improved, but the linkage between messages from the same UE is broken making message correlation difficult
Solution Approach 1:
The patent introduces a group-specific seed as an intermediary element that connects the source L2 identifier to the destination L2 identifier through a deterministic function. This intermediary allows the system to maintain privacy by changing identifiers while preserving the ability to correlate messages from the same UE, as the deterministic relationship between source and destination identifiers (mediated by the group-specific seed) ensures consistent mapping.
3Object-affected harmful factors
If cryptographic functions are used to generate pseudorandom destination identifiers, then privacy protection is improved, but computational complexity increases
Solution Approach 1:
The patent changes the approach from using heavy cryptographic functions to using a deterministic function that takes the source L2 identifier and group-specific seed as parameters. This parameter-based approach provides sufficient privacy protection by ensuring unique destination identifiers for each source UE while avoiding the high computational complexity of full cryptographic functions, thus achieving a balance between security and efficiency.
Data Source
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AI summary
The present disclosure provides a security mechanism to mitigate the risk of trackability of a UE engaged in groupcast communication. The security mechanism makes use of cryptographic functions and thus provides a cryptographic-grade protection for groupcast communications. The security mechanism can be implemented without any additional signaling for even additional parameters in existing signaling message.