Authenticated Debug Access for Integrated Circuit Evaluation
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Solution Overview
Problem
Debug interfaces in integrated circuit (IC) devices pose a security risk and are difficult to access for evaluation, as conventional methods like FIB modification are expensive, destructive, and temporary, preventing effective hardware evaluation.
Innovation Solution
A challenge/response process authenticates customers to temporarily or permanently enable access to the debug interface, allowing for software and hardware evaluation, and reconfiguring the IC to a default or customer-specific state for secure and efficient analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If FIB modification is used to regain access to the debug interface, then access to the debug interface is restored, but the process becomes expensive, destructive, and temporary
Solution Approach 1:
The patent implements a preliminary authentication mechanism that enables debug interface access before the customer disables it. The authenticated debug module allows the customer to temporarily re-enable the debug interface through challenge/response authentication before blowing the fuse, eliminating the need for post-disable restoration operations like FIB modification.
Solution Approach 2:
The patent introduces an authenticated debug module as an intermediary between the customer and the debug interface. This module performs challenge/response authentication and temporarily enables debug access without requiring physical modification of the IC device, serving as a non-destructive mediator that avoids the need for FIB modification.
2Ease of operation
If FIB modification is used to regain access to the debug interface, then access is restored, but the IC device structure is damaged and future evaluation is prevented
Solution Approach 1:
The authenticated debug module serves as a non-destructive intermediary that enables debug interface access through software-based challenge/response authentication. This eliminates the need for physical FIB modification and destructive deencapsulation, preserving the IC device structure and enabling future evaluation if needed.
Solution Approach 2:
The patent uses a temporary, software-based authentication mechanism rather than permanent physical modification. The debug interface can be temporarily enabled through authenticated challenge/response, providing a disposable, non-destructive access method that doesn't compromise the device's long-term integrity.
3Ease of operation
If FIB modification is used to regain access to the debug interface, then access is restored, but customer configuration is overridden and cannot be accessed for analysis
Solution Approach 1:
The patent enables preliminary authentication and temporary debug interface access before the customer blows the fuse. This allows the manufacturer to access and analyze customer configuration information through the debug interface while it is still accessible, eliminating the need to override the fuse and lose the configuration data.
Solution Approach 2:
The authenticated debug module provides a non-intrusive intermediary access path that allows configuration analysis without physical modification. The manufacturer can access customer configuration through the authenticated debug interface without blowing the fuse or deencapsulating the device, preserving all configuration information for analysis.
4Ease of operation
If FIB modification is used to regain access to the debug interface, then access is restored, but the solution is temporary due to metal migration that reconnects the blown fuse
Solution Approach 1:
The patent implements preliminary authentication that allows the customer to temporarily enable the debug interface before blowing the fuse. This provides sufficient time for the manufacturer to access and analyze the IC device through the debug interface without relying on temporary FIB-modified fuse states that are subject to metal migration.
Solution Approach 2:
The authenticated debug module provides a stable, software-controlled intermediary mechanism for enabling debug access. This eliminates reliance on physical fuse states that are subject to metal migration, providing a more reliable and controllable duration of access based on authentication sessions rather than physical degradation.
Data Source
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AI summary
Under the direction of a first party, an integrated circuit (IC) device (202) is configured to temporarily enable access to a debug interface (216) of the IC device (202) via authentication of the first party by a challenge/response process using a key (321, 322) of the IC device (202) and a challenge value (324) generated at the IC device (202). The first party then may conduct a software evaluation of the IC device (202) via the debug interface (216). In response to failing to identify an issue with the IC device (202) from the software evaluation, the first party can permanently enable open access to the debug interface (216) while authenticated and provide the IC device (202) to a second party. Under the direction of the second party, a hardware evaluation of the IC device (202) is conducted via the debug interface (216) that was permanently opened by the first party.