Spy Circuit for Secure Integrated Circuit Test Mode
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Solution Overview
Problem
Existing methods for testing integrated circuits, such as the internal scan method, make circuits vulnerable to fraudulent access and data manipulation during the test mode, particularly in circuits processing secret data, as they can be exploited to read or write unauthorized data.
Innovation Solution
An electronic circuit with a spy circuit that combines command signals and includes a state detection cell similar to configurable cells, which detects anomalies in signal states to prevent unauthorized access by producing an output signal representing an intrusion attempt, eliminating the need for manual placement and routing and reducing implementation costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the internal scan method is used to test integrated circuits, then the testability of the circuit is improved, but the circuit becomes vulnerable to fraudulent access and data manipulation
Solution Approach 1:
A spy circuit is introduced as an intermediary component between the test mode activation and the configurable cells. This spy circuit monitors the command signals and detects unauthorized access attempts by analyzing the state of control signals, thereby mediating between the test functionality and security requirements
Solution Approach 2:
The spy circuit continuously monitors the command signals and provides feedback about the state of control signals to detect anomalies. When unauthorized access is detected, the system can respond by preventing the test mode from activating or by alerting security mechanisms
2Object-affected harmful factors
If a spy circuit is added to detect fraudulent access, then the security against fraudulent attempts is improved, but the device complexity increases
Solution Approach 1:
The spy circuit is designed to perform multiple functions: it monitors command signals, detects unauthorized access attempts, and can trigger security responses. By making the spy circuit multi-functional, the overall device complexity is minimized while maintaining strong security capabilities
Solution Approach 2:
The spy circuit is integrated with the existing test mode activation mechanism and configurable cells, merging the security monitoring function with the existing circuit architecture. This integration reduces the additional complexity that would result from a completely separate security system
3Manufacturing precision
If manual placement and routing is used for the spy circuit, then the implementation precision can be controlled, but the manufacturing cost and time increase
Solution Approach 1:
The spy circuit is designed with self-placing and self-routing capabilities, allowing it to automatically integrate into the circuit layout without requiring manual intervention. This self-service approach maintains implementation precision while eliminating the time-consuming manual placement process
Solution Approach 2:
The spy circuit is pre-configured with its connection patterns and routing information before the actual manufacturing process. This preliminary action allows the circuit to be automatically placed and routed during manufacturing, eliminating the need for manual placement and reducing manufacturing time
Data Source
AI summary
An electronic circuit comprises configurable cells driven by command signals to adopt either a standard mode of operation in which they are integrated into a logic circuit, or a test mode in which they provide information on this logic circuit. The circuit includes a spy circuit capable of detecting an abnormal excitation of certain of the conductors through which the command signals travel, thus preventing fraudulent extraction of data out of the configurable cells. The spy circuit includes a logic combination circuit and a state detection cell.