Firmware Anomaly Detection via Instruction Groupcode Analysis

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Solution Overview

Problem

Electronic circuits with programmable processors face challenges in detecting firmware anomalies, particularly due to unpredictable behavior caused by factors like alpha particles, cross-talk, and supply voltage instabilities, which can lead to severe consequences without prior error detection mechanisms.

Innovation Solution

An electronic circuit with a programmable processor that includes an instruction decoder generating groupcodes from executable instructions, analyzed by a groupcode analyzer to detect anomalies within milliseconds, without requiring hardware duplication or additional code, using methods such as statistical analysis, neural networks, or predefined sequences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a programmable processor is used to provide flexibility in behavior, then adaptability is improved, but reliability deteriorates due to inability to guarantee 100% error-free behavior

Engineering Contradiction:
Improveflexibility in behaviorVSAvoiderror-free behavior guarantee
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a feedback mechanism where the instruction decoder continuously monitors executed instructions and feeds this information to a state machine that tracks expected versus actual behavior. This feedback loop enables the system to detect deviations from expected firmware behavior, allowing anomaly detection without sacrificing the flexibility of programmable processors.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent introduces an intermediary component - a state machine - that acts as a mediator between the instruction decoder and the anomaly detection function. This state machine translates instruction execution into observable states and compares them against expected behavior patterns, enabling reliable anomaly detection while preserving the adaptability of the programmable processor.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If error detection mechanisms are added to detect firmware anomalies, then reliability is improved, but device complexity increases

Engineering Contradiction:
Improveanomaly detection capabilityVSAvoidhardware structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the anomaly detection function with the existing instruction decoder by having the state machine integrated into the decoder's operation flow. The state machine uses the same clock signal and processes instructions through the existing pipeline, combining multiple functions (instruction decoding, state tracking, anomaly detection) into a unified structure that minimizes additional hardware complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The state machine performs self-service by automatically tracking its own state transitions and comparing them against expected behavior patterns without requiring external monitoring hardware. The anomaly detection is achieved through the state machine's intrinsic ability to monitor its own execution path, eliminating the need for separate complex monitoring systems.

Inventive Principle:
Principle #25Self-service

3Reliability

If comprehensive anomaly detection is implemented to detect all types of firmware errors, then reliability is improved, but measurement precision requirements increase

Engineering Contradiction:
Improvedetection accuracyVSAvoidbehavioral observation accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent segments the anomaly detection task into discrete, manageable components by defining specific observable behaviors and states that the state machine monitors. Instead of attempting to measure all possible firmware behaviors, the system divides detection into distinct categories (e.g., instruction sequence anomalies, state transition violations, timing deviations), each handled by the state machine's transition logic, thereby achieving reliable detection without requiring impossibly high measurement precision.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP4650967A1Electronic circuit with firmware anomaly detection
Publication Date: 2025.11.19 MELEXIS TECHNOLOGIES SA
  • EP4650967A1 patent drawingFigure 1~2
  • EP4650967A1 patent drawingFigure 3
  • EP4650967A1 patent drawingFigure 4

AI summary

An electronic circuit comprising: a processing unit comprising or connected to a memory containing a firmware with executable instructions; the processing unit comprising: an instruction decoder, instruction registers and an arithmetic Logical Unit; wherein the instruction decoder is configured for receiving instructions, and for converting them into operation codes and operands; and being further configured for generating one or more groupcode corresponding to the received instruction, thereby forming a stream of groupcodes during execution of said firmware by said processing unit; wherein the electronic circuit further comprises a groupcode analyser configured for receiving said stream of groupcodes, and for detecting anomalies in the firmware execution by analysing said stream of groupcodes.