Glitch Detection Circuit for FPGA Tampering
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Solution Overview
Problem
Existing systems lack effective detection mechanisms for transient voltage glitches that could indicate tampering attempts on field programmable gate arrays (FPGAs), compromising the security of sensitive data.
Innovation Solution
A glitch detection circuit that monitors the duration of a fractional supply voltage below a predetermined threshold, generating a glitch detect signal when the duration exceeds a set threshold, and includes a test glitch generator to verify operation, allowing for selectable voltage and duration criteria to detect various types of power source tampering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a glitch detection circuit is implemented to detect transient voltage glitches indicating tampering attempts, then security of FPGA data is improved, but device complexity increases due to additional monitoring circuits and components
Solution Approach 1:
The glitch detection circuit is integrated within the existing FPGA device structure, nesting the security monitoring function inside the target circuit's power supply network. The circuit uses the same power supply lines (VMAIN, VREF) that the FPGA already employs, embedding the detection functionality without requiring separate external monitoring equipment.
Solution Approach 2:
The glitch detection circuit serves multiple functions: it monitors voltage glitches, measures their duration, compares them against thresholds, and generates security alerts. Additionally, the test glitch generator provides both testing capability and calibration functionality, allowing the same hardware to serve detection and verification purposes.
2Measurement precision
If the glitch detection circuit monitors voltage duration below threshold to detect tampering, then detection precision is improved, but response time may be increased due to duration measurement requirements
Solution Approach 1:
The circuit pre-establishes threshold values for voltage monitoring and duration measurements before any glitch occurs. The comparator is pre-configured with reference voltages, and the duration counter is ready to immediately begin counting when a glitch is detected, eliminating setup delays during actual security events.
Solution Approach 2:
The duration filter quickly evaluates whether a detected glitch exceeds the predetermined time threshold and rapidly generates an alert signal. The circuit does not continuously measure all voltage variations but selectively processes only those glitches that meet the critical duration criteria, speeding up the response to genuine threats.
3Adaptability or versatility
If selectable trip points are provided between valid supply voltage and power-on reset threshold, then adaptability of detection criteria is improved, but device complexity increases due to multiple selection circuits
Solution Approach 1:
The voltage trip points and duration thresholds are made configurable rather than fixed, allowing the detection criteria to be dynamically adjusted based on specific application requirements. The selection circuits enable different voltage thresholds to be chosen depending on the operating conditions and security needs of the particular FPGA implementation.
4Reliability
If a test glitch generator is included to verify operation, then reliability of detection system is improved, but device complexity and power consumption increase
Solution Approach 1:
The test glitch generator is integrated within the glitch detection circuit itself, allowing the detection system to self-test and self-verify its functionality. The generator produces test glitches that are fed back into the detection circuit, enabling the system to monitor its own operation without requiring external test equipment.
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
The solution provides stable and reliable glitch detection across process, voltage, and temperature variations, enabling swift response to potential tampering attempts and safeguarding FPGA data by distinguishing between valid and unauthorized access.
Implementation Method 1
a first voltage divider configured to generate a plurality of voltage signals, each of the voltage signals representing a fraction of the MVSUPPLY voltage
Implementation Method 2
a comparator operably coupled to receive and compare the selected one of the plurality of voltage signals and the VREF to generate a depth detection signal
Data Source
AI summary
Apparatus and associated methods relate to a glitch detection circuit monitoring a duration that a selected fractional supply voltage is below a predetermined voltage threshold. The selected fractional supply voltage may be at the predetermined threshold when the supply voltage is between a valid circuit-supply voltage and a power-on circuit-reset (POR). A glitch detect signal may be generated, for example, when the monitored duration is greater than a predetermined duration threshold. A test glitch generator may generate a test glitch, for example, having selectable voltage and duration, which may be selectably applied to the glitch detection circuit to verify operation. Various exemplary glitch detection circuits may advantageously determine externally produced tampering attempts by detecting circuit-supply voltages and durations that meet specific selectable supply voltage and duration criteria, improving security of sensitive field programmable gate array (FPGA) data by taking protective action in response to the detection.