Built-In Self-Test Security via Segmented BIST Engines
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Solution Overview
Problem
In the manufacturing of integrated circuit (IC) devices, ensuring the secrecy of proprietary design features and test results during built-in self-test (BIST) procedures is challenging when different entities are involved in the manufacturing process, leading to increased costs due to the need for trusted parties to conduct these tests.
Innovation Solution
Implementing securely signed BIST software and BIST engines within the IC device, along with a test access port (TAP) that allows access to test results while maintaining secrecy through secure domains and unsecure domains, enabling BIST procedures to be conducted by parties that may not be fully trusted to maintain proprietary information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trusted parties conduct BIST procedures to maintain secrecy of proprietary information, then security of proprietary information is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the BIST system into distinct components: BIST engines embedded in the device under test, securely signed BIST software, and a test access port. This segmentation allows the testing function to be separated from the proprietary design, enabling non-trusted parties to conduct tests while the proprietary information remains protected within the device boundaries.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of securely signed BIST software and a chain of trust verification system. This intermediary allows non-trusted testing parties to interact with the device through a controlled interface that verifies authenticity and prevents unauthorized access to proprietary information, thus enabling cost-effective testing without compromising security.
2Ease of manufacture
If non-trusted parties conduct BIST procedures to reduce manufacturing cost, then manufacturing cost decreases, but security of proprietary information deteriorates
Solution Approach 1:
The patent implements preliminary action by embedding BIST engines and securely signing BIST software before the testing process begins. The chain of trust is established in advance through cryptographic signatures, ensuring that even when non-trusted parties conduct the testing, the proprietary information remains protected because the security measures were pre-configured within the device.
Solution Approach 2:
The device under test performs self-testing through embedded BIST engines that are triggered by external test commands. The device itself generates and executes test patterns, processes test stimuli, and produces test results, reducing the need for external trusted testing resources while maintaining security through the self-contained nature of the BIST functionality.
3Reliability
If BIST software is securely signed and BIST engines are implemented within the device, then secrecy of proprietary information is maintained, but device complexity increases
Solution Approach 1:
The patent merges the BIST functionality directly into the device by embedding BIST engines within the device architecture. This integration combines the testing functionality with the existing device resources, reducing the need for separate external testing equipment and minimizing the increase in device complexity while maintaining security.
Solution Approach 2:
The BIST engines are designed to be multi-functional, capable of handling various test patterns and scenarios through a unified architecture. The securely signed BIST software provides a universal interface that can accommodate different testing requirements without requiring separate hardware for each test type, thus limiting the increase in device complexity.
4Ease of operation
If test access port allows access to test results, then ease of operation is improved, but unauthorized access to sensitive information may occur
Solution Approach 1:
The test access port implements a feedback mechanism where test results are made accessible to authorized parties through a controlled interface. The system provides feedback on test status and results while simultaneously monitoring access requests, enabling easy retrieval of test information by legitimate users while preventing unauthorized access through verification of the chain of trust.
Solution Approach 2:
The patent applies local quality by providing different levels of access to different parts of the system. The test access port allows read access to test results for authorized parties while maintaining strict protection over the BIST engines and proprietary design information. This localized access control enables ease of operation for legitimate testing while preventing unauthorized access to sensitive information.
Data Source
AI summary
Disclosed are methods, systems and devices for implementing built-in self-test (BIST) to be performed by an untrusted party and/or in an unsecure testing environment. In an embodiment, a test access port (TAP) on a device may enable a party to initiate execution of one or more BIST procedures on the device. Additionally, such a TAP may enable loading of encrypted instructions to be executed by one or more processors formed on a device under test.