Secure Scan Chain Access via Configuration State Check
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Solution Overview
Problem
Scan chains in integrated circuit devices (ICs) pose security vulnerabilities as they can provide unauthorized access to sensitive data, allowing attackers to discern internal operational features and circuit implementations through physical attacks.
Innovation Solution
Implementing a secure mode in programmable ICs that prevents re-entry into operational mode until power cycled, by selectively enabling access to scan chains based on configuration states, and blocking access to non-erasable memory and input ports, ensuring sensitive data is secured before allowing DFT operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scan chains are made accessible for DFT operations, then testability and fault detection capability are improved, but security vulnerabilities increase allowing unauthorized access to sensitive data
Solution Approach 1:
The patent applies preliminary action by checking the configuration state before allowing scan chain access. The security controller determines whether the programmable IC is configured before enabling scan chain operations, preventing unauthorized access to sensitive data while allowing legitimate DFT operations on unconfigured devices.
Solution Approach 2:
The patent introduces a security controller as an intermediary between the scan chain and the external environment. This security controller acts as a gatekeeper that mediates access requests by evaluating configuration states and selectively enabling or disabling scan chain access based on security policies.
2Object-affected harmful factors
If scan chains are secured by preventing access, then security is improved, but testability and DFT operations are worsened
Solution Approach 1:
The patent applies dynamics by making scan chain accessibility dynamic rather than static. The scan chain transitions between accessible and inaccessible states based on the configuration state of the programmable IC, allowing the system to adapt its security posture according to operational context.
Solution Approach 2:
The patent changes the parameter of scan chain accessibility based on the configuration state parameter. When the IC transitions from unconfigured to configured state, the security controller modifies the accessibility parameter to prevent scan chain access, thereby maintaining security while preserving testability when appropriate.
3Object-affected harmful factors
If configuration state checking is implemented, then security control is improved, but device complexity increases
Solution Approach 1:
The security controller serves multiple functions: it monitors configuration state, determines accessibility, controls scan chain enabling, and enforces security policies. By consolidating these diverse functions into a single security controller, the patent reduces overall system complexity while maintaining robust security control.
Data Source
AI summary
A method of securing a design-for-test scan chain within a programmable integrated circuit device (IC) can include placing the programmable IC in an operational mode and responsive to a request to access a scan chain within the programmable IC, selectively enabling a secure mode within the programmable IC according to a configuration state of the programmable IC. Enabling secure mode within the programmable IC can provide access to the scan chain. Responsive to enabling the secure mode, the programmable IC can remain in the secure mode and be prevented from re-entering the operational mode until the programmable IC is power cycled.