Physical Layer Security via SSB Key Extraction
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Solution Overview
Problem
Current wireless communication systems, particularly 5G NR, face challenges in providing robust physical layer security to protect communications from eavesdropping, as existing security mechanisms are not sufficient to prevent unauthorized access and data breaches.
Innovation Solution
The implementation of a method where user equipment (UE) and network nodes exchange a secret key for physical layer security by extracting it from a reference signal, using a technique that involves channel randomness and key derivation functions, and indicate support for physical layer security through specialized SSB patterns and rasters, enabling secure communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional security mechanisms are used in wireless communication systems, then device complexity is kept low, but security reliability is insufficient to prevent eavesdropping and unauthorized access
Solution Approach 1:
The patent applies preliminary action by extracting and establishing secret keys from channel characteristics before actual communication occurs. The system performs channel estimation and secret key extraction during the initial connection phase, so that when data transmission happens, the security framework is already in place. This prevents the need for complex real-time security negotiations during communication.
Solution Approach 2:
The patent introduces channel characteristics (such as channel state information, reference signals, or synchronization signals) as an intermediary to establish security. Instead of direct key exchange between parties, the channel itself serves as the mediator that both parties independently use to generate identical secret keys. This eliminates the need for complex key distribution protocols while enhancing security.
2Reliability
If physical layer security is implemented using channel randomness and key derivation, then security protection against eavesdropping is enhanced, but the communication protocol complexity increases
Solution Approach 1:
The patent applies universality by using existing communication signals (reference signals, synchronization signals, or pilot signals) for dual purposes: both for channel estimation/quality assessment and for secret key extraction. This means the same signals that are already transmitted for communication purposes are also utilized for security, eliminating the need for separate dedicated signals and reducing overall system complexity.
Solution Approach 2:
The patent changes parameters by transforming channel characteristics (such as channel state information, signal strength, phase, or timing) into discrete secret key bits through quantization and hashing functions. This parameter transformation converts continuous physical layer measurements into discrete cryptographic keys that can be used with existing higher-layer security protocols, maintaining compatibility while adding security.
3Loss of time
If secret key extraction from reference signals is performed, then repeated pilot signals are eliminated, but measurement precision requirements increase
Solution Approach 1:
The patent applies feedback by using the measured channel characteristics to verify key extraction success and to adjust extraction parameters if needed. The system monitors whether the extracted keys match between transmitter and receiver and can request re-extraction or parameter adjustment, ensuring reliable key establishment even with varying measurement conditions.
Solution Approach 2:
The patent performs preliminary channel estimation and measurement during the initial access phase, before actual data transmission begins. This advance measurement ensures that high-precision channel characteristics are captured when the channel is relatively stable, and the results are stored for subsequent key extraction, eliminating the need for repeated measurements during communication.
Data Source
AI summary
A network node may transmit an SSB indicating that the network may support physical layer security, and a UE may extract the secret key for the physical layer security based on the received SSB indicating that the network may support the physical layer security. The network node may indicate a level of the physical layer security using the SSB, and the UE may determine the level of the physical layer security based on the received SSB. In one aspect, the indication that the network may support the physical layer security may be included in the SSB. In another aspect, a synchronization raster of the SSB may indicate that the network supports the physical layer security.