Scan Chain Security Control for Protecting Secure IC Assets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing integrated circuits (ICs) face challenges in protecting secure data during test operations, as test circuits can be exploited to access and modify secure data, posing a risk of unauthorized access and data compromise.
Innovation Solution
Implementing a security controller that transitions the SoC device into a secure mode, enabling access to secure data storage while disabling access during test operations, and using scan chains to flush residual secure data from non-resettable storage elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If test circuits are incorporated into IC designs to facilitate testing, then testing capability is improved, but security vulnerability increases as test circuits can be exploited to access and modify secure data
Solution Approach 1:
The patent segments the test circuit functionality by introducing a separate security controller that manages access to secure data. The security controller divides the system into secure and non-secure domains, allowing test operations to be performed without direct access to secure data storage elements. This segmentation prevents hackers from exploiting test circuits to access secure data while maintaining testing capability.
Solution Approach 2:
The security controller acts as an intermediary between the test circuit and secure data storage elements. It mediates access by enabling or disabling access to secure data based on operational mode, preventing direct access during test operations while allowing controlled access during secure operations. This intermediary protects secure data from unauthorized access through test circuits.
2Measurement precision
If scan chains are used to shift in test data for testing, then testing precision is improved, but data integrity risk increases as residual secure data may remain in non-resettable storage elements
Solution Approach 1:
The patent applies preliminary action by flushing scan chains with secure data before exiting secure mode. This preliminary flushing operation ensures that residual secure data is removed from non-resettable storage elements before normal operation resumes, preventing data integrity compromises while maintaining testing precision during secure operations.
Solution Approach 2:
The system changes the state parameter of scan chains by transitioning between secure mode and non-secure mode. In secure mode, scan chains are configured to handle secure data with specific access controls. In non-secure mode, access is disabled. This parameter change ensures data integrity is maintained during testing while preventing unauthorized access to secure data.
3Productivity
If access to secure data is enabled during test operations, then testing efficiency is improved, but security risk increases as secure data becomes exposed
Solution Approach 1:
The patent implements dynamics by making access to secure data conditional and changeable based on operational mode. The security controller dynamically enables or disables access to secure data storage elements according to whether the system is in secure mode or non-secure mode. This dynamic control allows testing efficiency to be maintained when needed while preventing security risks during unauthorized access attempts.
Solution Approach 2:
The security controller incorporates feedback mechanisms to monitor operational mode and adjust access controls accordingly. When secure mode is detected, access to secure data is enabled for authorized operations. When non-secure mode is detected, access is automatically disabled, providing feedback-based protection against security risks while maintaining testing efficiency during authorized operations.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Methods and apparatus are described to protect secure assets using scan operations. One example apparatus includes logic circuitry including a scan chain (212) that includes data storage elements (232, 234, 236) and design logic (216) coupled to the scan chain. The example apparatus also includes data storage (202) to store secure data. The design logic is coupled to the data storage. The example apparatus also includes a security controller (240) to transition the apparatus out of a secure mode of operation. The transition includes the security controller to cause the scan chain to serially shift secure scan data from an input of the scan chain into each data storage element of the data storage elements of the scan chain.