NBTI Degradation for Circuit Hacking Detection
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Solution Overview
Problem
Existing methods for detecting hacking attempts in electronic circuits, such as hidden channel attacks, do not effectively account for the time factor, making it difficult to distinguish between normal operation and potential hacking attempts based on the frequency of operations.
Innovation Solution
A method using P-channel MOS transistors placed in temperature instability conditions to monitor the saturation current and detect anomalies by comparing voltages across resistive elements, triggering a detection signal when a threshold is exceeded, allowing for the differentiation between normal and abnormal operation frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a counter is used to monitor the number of executions of sensitive algorithms, then the detection of hacking attempts is improved, but the time factor is not taken into account making it difficult to distinguish between normal and abnormal operation frequencies
Solution Approach 1:
The patent applies parameter changes by utilizing the NBTI effect to transform the static counting problem into a dynamic measurement problem. Instead of simply counting executions, the system measures saturation current which changes over time based on operation frequency, thereby incorporating the time factor into the detection mechanism and enabling distinction between normal and abnormal operation patterns
Solution Approach 2:
The patent replaces the mechanical/electronic counter system with a physics-based measurement system using P-channel MOS transistors and NBTI effect. This substitution allows continuous monitoring of operation frequency through current measurements rather than discrete counting, enabling time-based analysis of operation patterns
2Reliability
If the counter value is stored in non-volatile memory (EEPROM) to persist across reinitializations, then the detection of repeated attacks is improved, but the circuit complexity and space requirements increase
Solution Approach 1:
The patent applies self-service by using the NBTI degradation effect as a natural, self-updating record of operation frequency. The transistor's saturation current automatically reflects the cumulative operation history without requiring external memory storage or complex bookkeeping circuits, thereby maintaining detection reliability while reducing circuit complexity
Solution Approach 2:
The patent uses a simple P-channel MOS transistor as a disposable-like element that naturally degrades over time with use. This transistor serves as a temporary record of operation frequency that can be reset by reinitializing the circuit, eliminating the need for persistent non-volatile memory storage while maintaining reliable detection across attack cycles
3Measurement precision
If P-channel MOS transistors are placed in NBTI degradation conditions to monitor operation frequency, then the detection of hacking attempts is improved by considering time factor, but the transistor experiences stress and degradation
Solution Approach 1:
The patent converts the harmful NBTI degradation effect into a beneficial measurement mechanism. The very stress and degradation that would normally be considered harmful are utilized to create a time-dependent current signal that encodes operation frequency information, thereby transforming reliability degradation into a useful detection feature
Solution Approach 2:
The patent applies dynamics by allowing the transistor parameters to change over time through controlled NBTI stress. The saturation current dynamically reflects the operation history, enabling frequency detection. The system manages this dynamic degradation by controlling stress periods and allowing recovery, balancing measurement needs with component reliability
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
This approach enables the effective monitoring of operation frequencies over time, enhancing the detection of hacking attempts by considering both the number and timing of operations, reducing the need for frequent memory writes and minimizing circuit stress, while being simple to implement and adaptable to various functions.
Implementation Method 1
a first P-channel MOS transistor is placed in temperature instability type degradation conditions by negative bias during periods when the signal to be monitored is in a first state
Data Source
Figure 1~3
Figure 4~5D
AI summary
The invention relates to a method and device for monitoring a digital signal (EN), in which: a first P-channel MOS transistor (P1) is placed under negative bias temperature instability (NBTI) degradation conditions during periods when the signal to be monitored is in a first state; a first information (VMES) representative of the saturation current of the first transistor (P1) is measured when the signal to be monitored passes into a second state; and a detection signal (DET) is switched when this first information passes a threshold.