Flip-Flop Control Signal Integrity Checking Against Force Attacks
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Solution Overview
Problem
Integrated circuits are vulnerable to attacks that manipulate control signals, such as reset and scan test signals, which can compromise the integrity of data storage elements like flip-flops, and existing methods fail to effectively detect and protect against these attacks.
Innovation Solution
A circuit comprising a plurality of flip-flops, a control circuit, and an integrity checking circuit that feeds back control signals to verify their integrity, utilizing feedback mechanisms like OR and AND gates to detect mismatches and trigger alarm signals in case of force-1 or force-0 attacks, thereby ensuring the flip-flops receive intended control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If control signals are provided to multiple flip-flops without integrity checking, then device complexity is reduced and ease of operation is improved, but reliability deteriorates due to vulnerability to force attacks on reset and scan test signals
Solution Approach 1:
The patent implements feedback by having each flip-flop return its received control signal to the control circuit through a feedback circuit. The control circuit then compares the originally provided control signal with the feedback signal to detect any deviations caused by force attacks. This feedback mechanism enables reliability improvement without requiring complete redesign of the control architecture.
Solution Approach 2:
The patent segments the control signal verification process into individual flip-flop level checks. Each flip-flop independently returns its received control signal, allowing the control circuit to verify integrity for each flip-flop separately. This segmentation enables targeted detection of attacks on specific flip-flops while maintaining overall system functionality.
2Reliability
If integrity checking circuit is added to detect force attacks, then reliability is improved, but device complexity increases due to additional circuits and feedback paths
Solution Approach 1:
The control circuit is designed to perform multiple functions: it originally provides control signals to flip-flops and now also performs integrity checking by comparing provided signals with feedback signals. This multi-functionality reduces the need for completely separate verification circuits, thereby limiting the increase in device complexity while maintaining improved reliability.
Solution Approach 2:
The feedback circuit acts as an intermediary that transports the received control signal from each flip-flop back to the control circuit. This intermediary structure enables the comparison mechanism without requiring direct complex wiring between all flip-flops and the control circuit, thus managing complexity through standardized feedback paths.
3Measurement precision
If feedback circuits are implemented for each flip-flop, then measurement precision of control signal integrity is improved, but device complexity increases due to additional feedback paths
Solution Approach 1:
The patent implements preliminary action by having each flip-flop immediately return its received control signal via feedback circuits as soon as it receives the signal. This preliminary feedback enables the control circuit to detect deviations before they can cause harmful effects, improving measurement precision of signal integrity while using simple, direct feedback paths that limit complexity growth.
Data Source
AI summary
According to an embodiment, a circuit is described comprising a plurality of flip-flops, a control circuit configured to provide a control signal to each flip-flop of the plurality of flip-flops and an integrity checking circuit connected to the control circuit and to the plurality of flip-flops configured to check whether the flip-flops receive the control signal as provided by the control circuit.