Mobile Terminal Configuration Update via Digital Signatures
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Solution Overview
Problem
Existing methods for updating configuration parameters in mobile terminals lack strict control over hardware IDs and do not provide an efficient, secure mechanism for updating or recovering security-sensitive parameters, especially when corruption occurs or when terminals change ownership.
Innovation Solution
A method involving a central signing server and decentralized update/recovery servers uses public-key cryptosystems to generate and verify digital signatures for updating or recovering configuration parameters, ensuring secure and controlled updates while allowing for detection of tampering and unauthorized changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If security critical parameters are written in a One-Time-Programmable (OTP) portion of the memory to prevent tampering, then security against unauthorized modification is improved, but the ability to update parameters when corruption occurs or ownership changes is lost
Solution Approach 1:
The memory is divided into two distinct segments: OTP memory for storing immutable security critical parameters ( preventing tampering) and rewritable flash memory for storing updateable configuration parameters (enabling updates when needed). This segmentation allows the system to simultaneously achieve both security against unauthorized modification and the flexibility to update parameters under controlled conditions.
Solution Approach 2:
A secure update mechanism acts as an intermediary between the OTP memory and the rewritable flash memory. This mechanism includes authentication protocols and digital signatures that verify the legitimacy of update operations, allowing parameters to be updated only when authorized and when genuine corruption or legitimate ownership transfer occurs, thus mediating between the immutability of OTP and the updatability of flash memory.
2Reliability
If a centralized control mechanism is implemented to maintain strict control over hardware IDs, then security control is improved, but the efficiency and scalability of worldwide updates is reduced
Solution Approach 1:
The update system is segmented into a centralized authentication server that maintains control over hardware ID generation and validation, and decentralized update servers that can be distributed worldwide. The centralized server signs update packages with digital signatures, while decentralized servers deliver these updates to terminals. This segmentation maintains centralized control authority while enabling efficient distributed update delivery across the globe.
Solution Approach 2:
Update packages are pre-signed with digital signatures by the centralized authentication server before distribution. This preliminary authentication action allows decentralized update servers to distribute updates without needing real-time connection to the central server, improving update efficiency while the pre-established digital signatures ensure centralized control integrity is maintained throughout the distribution process.
3Ease of operation
If existing update methods are used without strict control mechanisms, then ease of operation is improved, but the ability to detect and prevent unauthorized changes is reduced
Solution Approach 1:
The system implements feedback mechanisms where terminals periodically verify the integrity of their configuration parameters against authenticated reference values stored in OTP memory. Update servers provide feedback about the authenticity of update packages through digital signatures. This feedback loop enables automatic detection of unauthorized changes while maintaining straightforward update operations for legitimate changes.
Solution Approach 2:
The system creates authenticated copies of security critical parameters: the original parameters are stored in OTP memory, while authenticated reference copies are stored in rewritable flash memory with digital signatures. Terminals can compare current parameters against these authenticated copies to detect tampering. This copying approach enables easy verification of integrity without complicating the update process, as legitimate updates simply replace parameters with newly authenticated copies.
Data Source
AI summary
A method of updating/recovering a configuration parameter of a mobile terminal having stored thereon a public key of a public-key cryptosystem and a current terminal identifier, the method comprising determining an updated configuration parameter by an update/recovery server in response to a received current terminal identifier from the mobile terminal; generating an update/recovery data package by a central signing server, the update/recovery data package including the current terminal identifier, the updated configuration parameter, and a digital signature based on a private key, where the digital signature is verifiable by said public key; storing the current terminal identifier and the updated configuration parameter by the central signing server; sending the update/recovery data package by the update/recovery server to the mobile terminal causing the mobile terminal to verify the received update/recovery data package and to store the! updated configuration parameter of the verified update/recovery data package in the mobile terminal.