IC Intrusion Detection Circuit Using Random Signal Timing
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Solution Overview
Problem
Conventional methods for detecting intrusion attacks on integrated circuit chips are inadequate as they can be fooled by external sections duplicating the conductive path to simulate electric continuity, thereby failing to prevent unauthorized access.
Innovation Solution
A circuit that applies a random signal to a conductive path and compares it with a delayed signal, using a clock signal synchronized with the propagation delay between two conductive paths to detect any modifications in the path's properties, ensuring that the comparison time is longer than the propagation delay, thus preventing false alarms from external interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conductive path is used to detect intrusion attacks, then the detection capability is provided, but the path can be duplicated by external sections to simulate electric continuity, causing false negatives
Solution Approach 1:
The patent applies a random signal to the conductive path before the actual detection process. This preliminary action establishes a known reference state that is temporally correlated with the expected signal arrival at the comparison point. By pre-establishing this reference, the system can later verify whether the received signal matches both the random pattern and the expected time delay, making it impossible for external duplicators to simulate continuity without knowing the random sequence in advance.
Solution Approach 2:
The patent introduces dynamic elements by using a random signal that changes over time rather than a static test signal. The random nature of the signal creates a time-varying reference pattern that must be matched both in value and in temporal arrival. This dynamic approach prevents external sections from duplicating the path because they cannot predict or replicate the random signal values and their precise timing without internal knowledge of the signal generation process.
2Measurement precision
If a random signal is applied to detect path modifications, then detection accuracy is improved, but the system becomes more complex with synchronization requirements
Solution Approach 1:
The patent segments the detection function into two distinct parts: a signal generation segment that creates the random signal and applies it to the conductive path, and a comparison segment that receives both the applied signal and the delayed signal from the path. This segmentation allows each part to be optimized independently - the generation side focuses on creating unpredictable random patterns, while the comparison side focuses on temporal correlation and pattern matching, simplifying the overall synchronization requirements.
Solution Approach 2:
The patent implements a feedback mechanism where the output of the comparison process feeds back into the detection logic. The comparison result, which indicates whether the delayed signal matches the expected random pattern, provides feedback that confirms or rejects the integrity of the conductive path. This feedback loop enables the system to continuously verify path integrity without requiring complex external synchronization, as the random signal itself carries the temporal reference needed for comparison.
Data Source
AI summary
A circuit for detecting attacks by contacting an integrated circuit chip comprising means for applying a random signal to a first terminal of at least one conductive path formed in at least one first metallization level of the chip, means for comparing the applied signal with a signal present on a second terminal of the path, and means for delaying the comparison time with respect to the application time, of a duration longer than or equal to the propagation delay through the first path.