Sensory Input Attestation Using Injected Noise Signals
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Solution Overview
Problem
Existing attestation methods for embedded devices rely on passive power fingerprinting, which can lead to false positives or negatives due to reliance on understanding normal power consumption levels, making it difficult to validate the integrity of sensory input data.
Innovation Solution
Generate a noise signal representing an expected data stream using output artifacts, emit an aggregate output signal, receive and extract a noise signal from the input signal using input artifacts, and compare the received data stream with the expected data stream to validate integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive power fingerprinting is used for attestation, then the system can validate code execution, but it produces false positives or false negatives due to reliance on understanding normal power consumption levels
Solution Approach 1:
The patent replaces passive electrical power measurement with active acoustic signal injection and detection. Instead of measuring power consumption characteristics, the system uses speakers to emit encoded acoustic signals and microphones to receive them, substituting an acoustic field-based system for an electrical power measurement system. This eliminates the false positives/negatives associated with power fingerprinting.
Solution Approach 2:
The system performs preliminary encoding of validation data into acoustic signals before emission. The speaker emits pre-encoded acoustic signals that contain validation information, and the microphone receives these signals before any potential tampering can occur. This preliminary encoding and transmission of validation data allows for proactive integrity verification rather than reactive power analysis.
2Reliability
If active acoustic signal injection is used, then sensory input integrity can be validated reliably, but device complexity increases due to additional hardware components
Solution Approach 1:
The patent leverages existing multi-functional components in embedded devices. Speakers, which are already present for audio output, are used for both normal audio functions and for emitting validation signals. Microphones, already present for audio input, serve dual purposes for normal audio capture and validation signal reception. This multi-functionality approach adds validation capability without requiring entirely new hardware components.
Solution Approach 2:
The system uses the device's own existing audio hardware (speaker and microphone) to perform self-validation. The embedded device generates, emits, receives, and processes its own validation signals using components already dedicated to other functions. This self-service approach eliminates the need for separate dedicated validation hardware, reducing overall system complexity.
Data Source
AI summary
Methods of sensory input integrity attestation are provided. Artifacts included within devices under test inject a known noise signal into the output signal of one or more output devices that are detectable by one or more input devices (i.e., sensors) of an embedded device, and monitor the received input data. By comparing the received signal against the expected noise signal, attestation of the validity of sensory input data is possible. Such sensory input data attestation is capable either locally or using a remote attestation device with knowledge of the expected data stream.