Thermal Memory Circuit for Fault Injection Sequence Detection

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing fault injection detection methods in integrated circuits suffer from false positives and negatives, leading to undesirable extreme reactions or ineffective temporary blocking of attacks, as attackers can quickly reset and vary parameters.

Innovation Solution

A thermal memory device with a heating element and fault injection detector is used to detect and record fault injection attempts, allowing a security control circuit to identify sequences that meet a density criterion, triggering responsive actions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fault injection detection circuitry is used to detect fault injection attempts, then detection capability is improved, but false positives and negatives occur leading to unreliable protection

Engineering Contradiction:

Improvefault injection detection reliabilityVSAvoiddetection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by using thermal memory to record fault injection attempts before they can cause damage. The thermal storage zone is written to when a fault injection attempt is detected, creating a historical record that can be reviewed later to confirm whether the detection was a true positive or false alarm, thereby improving reliability without immediately reacting to each detection event.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by reading the thermal memory contents to determine whether a sequence of fault injection attempts meets a density criterion. This feedback mechanism allows the system to learn from past detections and adjust its response accordingly, filtering out false positives while maintaining detection of genuine attack patterns.

Inventive Principle:

Principle #23Feedback

2Reliability

If temporary blocking of attacks is implemented, then some protection is achieved, but attackers can quickly reset and vary parameters making the protection ineffective

Engineering Contradiction:

Improveattack protection effectivenessVSAvoidprotection duration

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The thermal memory stores historical information about fault injection attempts, allowing the system to prepare and respond more effectively to subsequent attacks. By maintaining a record of past attempts, the system can identify patterns and extend the effective protection duration beyond immediate temporary blocking.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of reacting to each fault injection attempt immediately, the system takes a more measured approach by using thermal memory to accumulate evidence over time. This partial action approach allows the system to filter out isolated false alarms while maintaining protection against systematic attacks, effectively extending the duration of meaningful protection.

Inventive Principle:

Principle #16Partial or excessive action

3Productivity

If thermal memory is used to record fault injection attempts, then repeated fault injections are slowed down, but device complexity increases

Engineering Contradiction:

Improveattack execution speedVSAvoidcircuit complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent replaces traditional digital memory storage with a thermal memory mechanism that uses physical thermal properties to store information. This substitution simplifies the overall circuit design by eliminating the need for complex digital storage arrays while still achieving the goal of recording fault injection attempts and slowing down repeated attacks.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach significantly slows down repeated fault injections, rendering automatic attacks with varying parameters ineffective, and ensures reliable protection against systematic attacks.

Implementation Method 1

a heating element configured to heat the thermal storage zone in response to write operations

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

a thermal storage zone... to identify a sequence of the attempts that meets a density criterion, by reading the thermal memory device

Methodology Applied

Scientific EffectThermal energy storage: Thermal Energy Storage

Data Source

PatentUS12499227B2Tracking and prevention of fault injection attempt sequences using thermal memory

Publication Date: 2025.12.16 NUVOTON

AI summary

An integrated circuit (IC) includes a thermal memory device, a fault injection (FI) detector and a security control circuit. The thermal memory device includes (i) a thermal storage zone and (ii) a heating element configured to heat the thermal storage zone in response to write operations. The FI detector is configured to detect attempts to inject faults into the IC. The security control circuit is configured to perform a write operation to the thermal memory device in response to an attempt detected by the FI detector, to identify a sequence of the attempts that meets a density criterion, by reading the thermal memory device, and initiate a responsive action upon identifying the sequence.