Two-Stage Ciphering for Mobile Communications
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Solution Overview
Problem
In mobile telecommunication networks, particularly those following 3GPP standards, there is a challenge in ensuring proper ciphering and deciphering of data before the confirmation message is received after the activation time, leading to incomplete data transmission and reception.
Innovation Solution
A method involving a two-stage ciphering process, where initial data transmission and reception use previous cipher values until new cipher data is communicated, allowing seamless transition to new cipher parameters at defined activation times, ensuring continuous and secure data exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the network sends configuration data with Activation Time to the UE, then the UE can be configured with correct parameters for communication, but the confirmation message may not be sent until after the Activation Time causing data to be sent unciphered
Solution Approach 1:
The network performs preliminary ciphering preparation by generating new cipher data and calculating the cipher activation time in advance, before the UE sends the confirmation message. This allows the network to be ready to switch to new ciphering parameters immediately when the activation time is reached, eliminating the security gap that would otherwise exist during the confirmation delay period.
Solution Approach 2:
The system dynamically switches between two ciphering stages: first stage uses previous cipher data before activation time, and second stage uses new cipher data after activation time. This dynamic transition ensures continuous secure ciphering throughout the configuration process, resolving the contradiction between timely configuration and continuous security.
2Ease of operation
If the UE configures internal resources and sends confirmation message after Activation Time, then the configuration is confirmed, but any data sent before receiving confirmation cannot be deciphered properly
Solution Approach 1:
The network calculates the cipher activation time in advance based on the activation time and estimated confirmation message timing, and prepares the new cipher data beforehand. This preliminary preparation ensures that when data is sent during the configuration period, both UE and network can properly cipher and decipher it using the appropriate cipher stage, maintaining reliability while allowing easy configuration setup.
3Reliability
If the network starts ciphering downlink data after receiving confirmation message, then ciphering is synchronized, but data transmitted before confirmation cannot be deciphered
Solution Approach 1:
The system implements dynamic ciphering with two distinct stages: first stage ciphering uses previous cipher data for data transmitted during configuration setup, and second stage ciphering uses new cipher data after activation time. This dynamic approach maintains cipher synchronization reliability while ensuring continuous data transmission productivity without interruptions or deciphering failures.
Solution Approach 2:
The ciphering parameters are changed at a calculated activation time that accounts for the confirmation message delay. The system transitions from using previous cipher data to new cipher data at this predetermined point, ensuring that both UE and network use matching parameters for any data transmitted during the transition period, thereby maintaining both synchronization and continuity.
Data Source
AI summary
A mobile communications system is proposed in which a two stage procedure is used for setting up Radio Bearers within a mobile communications device and UTRAN. In the first stage, both the mobile device and UTRAN perform ciphering based on an old Start value. In the second stage, the mobile device and UTRAN perform ciphering based on a new Start value. In this way, data communication using the Radio Bearers can start without waiting for the mobile device to confirm completion of the setup procedure.