Microcircuit Update Rule Verification for Smart Card Reliability
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Solution Overview
Problem
Smart cards, particularly those following the EMV standard, can be rendered partially or completely non-functional due to erroneous or malicious update commands, leading to blocked states from which they cannot be restored.
Innovation Solution
Implementing a control method within the microcircuit that verifies update rules by checking if new values of configuration data fall within authorized lists or depend on existing objects, preventing commands from placing the card in an unusable state by ensuring compliance with predefined authorized values and dependency rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If update commands are allowed to modify configuration data without verification, then the microcircuit can be reconfigured flexibly, but the microcircuit may be placed in a non-functional state
Solution Approach 1:
The patent applies preliminary action by pre-defining authorized values and dependency rules during the personalization phase, before the microcircuit is deployed. These rules are stored in the microcircuit and automatically verified before any update command is executed, preventing invalid configurations from being applied and thus avoiding non-functional states while maintaining reconfiguration capability
Solution Approach 2:
The patent implements feedback by having the microcircuit automatically verify update rules against stored authorized values and dependency relationships before applying any configuration changes. This verification feedback mechanism prevents invalid updates and ensures the microcircuit remains in a functional state, resolving the contradiction between flexibility and reliability
2Reliability
If update rules verification is implemented, then the microcircuit remains functional, but the complexity of update operations increases
Solution Approach 1:
The verification rules and authorized values are prepared in advance during the personalization phase, stored in the microcircuit memory, and automatically applied during update operations. This preliminary preparation eliminates the need for complex runtime verification logic and reduces the complexity of update operations while maintaining reliability
Solution Approach 2:
The microcircuit performs self-verification of update rules using stored authorized values and dependency rules, without requiring external verification systems. This self-service approach simplifies the overall system architecture and reduces operational complexity while ensuring the microcircuit remains functional
3Reliability
If authorized values are stored in microcircuit memory, then update verification can be performed, but memory space is consumed
Solution Approach 1:
The patent stores only the essential authorized values and dependency rules in the microcircuit memory, rather than all possible configuration data. This partial storage approach provides sufficient verification capability to prevent non-functional states while minimizing memory space consumption, resolving the contradiction between verification capability and memory usage
Data Source
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AI summary
A control device and method implemented by a microcircuit comprises: - a reception (B3) of a command to update a first object stored in the microcircuit, indicating an updated value for the first object, - a verification (B4, B4') of an update rule for said first object, taking into account said updated value for the first object. The invention finds application in microcircuits implementing transactions.