5G UE AS Key Generation via SSB Frequency and NCC

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Solution Overview

Problem

In 5G communication systems, there is a lack of specific solutions for ensuring the security of user equipment (UE) communication, particularly during RRC connection reestablishment and handover processes, where multiple Synchronization Signal Blocks (SSBs) are managed uniformly by a Cell-Radio Network Temporary Identifier (C-RNTI), leading to potential security vulnerabilities.

Innovation Solution

A method is introduced where key parameters, including a Next Hop Chaining Counter (NCC) and frequency information of a target cell's SSB, are used to generate an Access Stratum (AS) key, ensuring secure communication by enabling encryption and integrity protection through the exchange of key-related parameters between the UE and the network device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If multiple SSBs are managed uniformly by a single C-RNTI in a wideband carrier, then device complexity is reduced and management is simplified, but communication security is compromised

Engineering Contradiction:

Improvemanagement complexityVSAvoidcommunication security

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent segments the unified C-RNTI management into separate key management units for each SSB. Each SSB is associated with its own key parameters (NCC, frequency information) and AS key, dividing the previously unified security management into multiple independent security domains while maintaining overall system coordination.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies local quality by making security parameters specific to each SSB rather than uniform across all SSBs. Each SSB receives customized key parameters including NCC values and frequency information tailored to its characteristics, enabling differentiated security protection for different synchronization blocks within the same wideband carrier.

Inventive Principle:

Principle #3Local quality

2Reliability

If key parameters including NCC and frequency information are exchanged between UE and network device, then communication security is enhanced, but information exchange overhead increases

Engineering Contradiction:

Improvecommunication securityVSAvoidinformation overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent implements preliminary action by pre-configuring key parameters (NCC, frequency information) in the network device before actual key generation is needed. These parameters are prepared in advance and only exchanged when required for AS key generation, reducing unnecessary information overhead while ensuring security parameters are ready when needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE generates its own AS key using the received key parameters (NCC and frequency information) without requiring the network device to directly provide the final key. This self-service approach allows secure key generation while minimizing the amount of sensitive information that needs to be transmitted over the air interface.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS11153757B2Method for instructing user equipment to obtain key, user equipment and network device

Publication Date: 2021.10.19 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD

AI summary

A method for generating a key includes: obtaining key parameters indicated by a network side, the key parameters at least comprising a next hop chaining counter (NCC) and frequency point information for generating a key, the frequency information being a frequency of one Synchronization Signal Block (SSB) of a target cell; and generating an AS key based on the key parameters.