SoC Supply Proportion Checking for Power-Up Voltage Attack Detection

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Solution Overview

Problem

Existing system-on-chip (SoC) voltage monitoring technologies are insufficient to detect certain attack scenarios, particularly during power-up when trim values are not yet available, leaving the SoC vulnerable to hacking through supply voltage manipulation.

Innovation Solution

Implementing a supply proportion checker that monitors the legitimacy of voltage rails within the SoC by checking their proportions and switch control settings, allowing for early activation at power-up without requiring trim values, and issuing a reset if any rule violations are detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional high/low voltage monitors are used to determine whether supply voltage is within acceptable range, then voltage monitoring capability is provided, but the monitors cannot detect certain attack scenarios and are not functional at power-up until trim values are loaded

Engineering Contradiction:

Improvevoltage monitoring reliabilityVSAvoidvulnerability window duration

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The supply proportion checker is designed to perform preliminary voltage proportionality checks immediately at power-up, before trim values are loaded and applied to traditional voltage monitors. This preliminary action occurs during the reset sequence execution, establishing early protection against voltage manipulation attacks before the system becomes fully operational.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The supply proportion checker acts as an intermediary monitoring mechanism that operates independently of traditional high/low voltage monitors. It provides an additional layer of verification by checking voltage proportions between different supply rails, complementing the absolute voltage threshold monitoring and filling the security gap during the trim value loading period.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If trim values are required for voltage monitors to properly determine acceptable voltage range, then measurement precision is improved, but the monitors cannot be activated until after power-up when trim values are available

Engineering Contradiction:

Improvevoltage range determination accuracyVSAvoidmonitor activation speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The supply proportion checker performs preliminary proportionality assessments using resistor ratios that do not require trim values. By establishing baseline proportion relationships during power-up before trim loading, the system can immediately detect gross voltage manipulation anomalies without waiting for precision calibration data to become available.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The monitoring approach transitions from checking absolute voltage thresholds (which require trim values for precision) to checking voltage proportionality ratios between supply rails. This parameter change allows the system to monitor voltage relationships using fixed resistor ratios that are immediately available at power-up, bypassing the trim value dependency.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If supply rails are made switchable to support different power modes, then adaptability is improved, but hackers can exploit these rails to attack the SoC by oversupplying, undersupplying, or powering through illegitimate paths

Engineering Contradiction:

Improvepower mode switching capabilityVSAvoidvoltage manipulation attack susceptibility

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The supply proportion checker continuously monitors voltage proportions between supply rails and provides feedback about the legitimacy of voltage relationships. When voltage manipulation is detected through proportionality violations, the system can trigger protective actions such as resetting the SoC or disabling affected supply rails, creating a closed-loop security mechanism.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The supply proportion checker establishes preliminary security checks that prevent voltage manipulation attacks before they can compromise system operation. By continuously verifying voltage proportionality relationships, the system proactively counteracts potential attacks through oversupplying, undersupplying, or illegitimate power paths.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS11977664B2Supply voltage proportionality monitoring in a system-on-chip (SOC)

Publication Date: 2024.05.07 NXP USA INC

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.