SoC Supply Proportion Checker for Power-Up Voltage Attack Detection
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Solution Overview
Problem
Existing on-chip voltage monitors are insufficient to detect certain attack scenarios and are often not enabled at power-up, leaving SoCs vulnerable to hacking attempts through manipulation of supply voltages.
Innovation Solution
Implementing a supply proportion checker within the SoC to monitor and ensure legitimate voltage rail proportions across different paths and domains, using passive elements that do not require trim values, allowing early activation and detection of illegitimate voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional high/low voltage monitors are used, then voltage range monitoring is provided, but the monitors cannot detect certain attack scenarios and are not functional at power-up
Solution Approach 1:
The supply proportion checker is designed to activate immediately at power-up, performing preliminary monitoring of voltage rail proportions before the SoC completes its reset sequence. This preliminary action closes the vulnerability window that exists between power-up and when traditional voltage monitors become operational, detecting potential attacks before they can compromise the system.
Solution Approach 2:
The monitoring function is segmented into two complementary components: traditional high/low voltage monitors that activate after trim values are loaded, and the supply proportion checker that activates immediately at power-up. This segmentation allows each component to specialize in different detection scenarios, with the proportion checker handling early power-up monitoring and the traditional monitors handling precision voltage range monitoring.
2Measurement precision
If trim values are required for voltage monitoring, then precise voltage level detection is achieved, but the monitor cannot be activated until after power-up
Solution Approach 1:
The supply proportion checker extracts the essential monitoring function from the traditional voltage monitor design by removing the dependency on trim values. It uses a simplified proportionality check mechanism that compares voltage rails directly without requiring calibration data, allowing immediate activation at power-up while traditional monitors handle precision measurements after trim values are available.
3Use of energy by moving object
If supply rails are made switchable for different power modes, then power consumption is optimized, but security vulnerabilities increase due to additional attack surfaces
Solution Approach 1:
The supply proportion checker implements continuous feedback monitoring of voltage rail proportions across all supply paths, including switched rails. By constantly checking that voltage proportions remain within legitimate ranges, the system can detect attempts to exploit switched supply paths for attacks, providing security feedback that complements the power management functionality.
Data Source
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AI summary
A System-on-Chip (SoC) includes first and second voltage supply pins configured to receive first and second supply voltages, respectively, a first supply path beginning at the first supply pin, and a supply proportion checker. The first supply path includes a first plurality of voltage supply nodes and a supply switch coupled between adjacent voltage supply nodes, wherein each node is configured to provide a corresponding internal voltage supply to a corresponding portion of the SoC. The supply proportion checker is coupled to receive the corresponding internal voltage supply from each voltage supply node, and configured to determine whether a first internal voltage supply supplied by a first supply node of the first plurality of nodes has a legitimate proportion to a second internal voltage supply supplied by a second supply node of the first plurality of nodes, wherein the legitimacy is checked using only resistors which do not require trimming.