Null Ciphering Algorithm for NAS Signaling Interoperability
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Solution Overview
Problem
Interoperability issues arise in telecommunications networks due to the lack of a standardized method for un-ciphered operation in Non-Access Stratum (NAS) signaling, leading to complications in distinguishing between ciphered and un-ciphered NAS messages, which affects the security and integrity protection of communications between User Equipment (UE) and Mobility Management Entity (MME).
Innovation Solution
Implementing a 'null ciphering algorithm' for security contexts in MMEs, allowing for un-ciphered operation while maintaining integrity protection, by setting the ciphering algorithm to 'null' when un-ciphered mode is selected, and treating messages as if they were in normal ciphered mode, ensuring consistent handling and reduced complexity in MME implementations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If non security protected NAS messages are used for all messages in un-ciphered operation mode, then interoperability between UE and MME is improved, but MME implementation complexity increases and integrity protection is lost
Solution Approach 1:
The patent changes the ciphering algorithm parameter to a null algorithm when un-ciphered mode is selected, allowing the MME to treat all messages uniformly as if they were ciphered. This parameter change enables interoperability while avoiding the need for complex message-type differentiation and integrity protection mechanisms.
2Ease of operation
If non security protected NAS messages are used for all messages in un-ciphered operation mode, then un-ciphered operation is achieved, but integrity protection of NAS messages is lost
Solution Approach 1:
The null ciphering algorithm acts as an intermediary that allows un-ciphered operation to be achieved while maintaining the appearance of ciphered operation. This intermediary algorithm enables the system to treat un-ciphered messages as if they were ciphered, preserving integrity protection mechanisms without requiring actual ciphering.
3Adaptability or versatility
If a method is chosen where non security protected NAS messages are used for all messages in un-ciphered operation mode, then un-ciphered operation is enabled, but the MME needs to distinguish between ciphered and un-ciphered operation for most NAS messages
Solution Approach 1:
The null ciphering algorithm provides a universal solution that works for all NAS messages regardless of their original ciphering status. By using this universal algorithm, the MME no longer needs to distinguish between different message types or operation modes, simplifying message handling while enabling un-ciphered operation.
Data Source
AI summary
The present invention relates to a solution for handling security issues of non access stratum (NAS) signaling in a telecommunications network. The NAS signaling is performed between a user equipment (UE) and a mobility management node, e.g. a mobility management entity (MME). The solution is realized in a device and in a method comprising steps of receiving an initial non access stratum message from the UE communicating wirelessly with the telecommunications network, determining security context status for the UE, determining if unciphered mode is to be used in the security context, set ciphering algorithm to a null ciphering algorithm, transmitting a security context and activation message to the UE, comprising information indicating ciphering algorithm, and receiving a security context activation acknowledge message from the UE.