Method and system for detection of tampering related to reverse engineering
Inventors
Assignees
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Publication Number
US-8242790-B2
Publication Date
2012-08-14
Expiration Date
Abstract
A sensor system for protecting products and technology from reverse engineering by detecting attempts to probe electronic circuitry includes a sensor electrically linked to electronic circuitry. The sensor detects interaction of probe devices with the electronic circuitry for the purpose of reverse engineering the electronic circuitry. The sensor includes an exciter and an impedance counter linked to the exciter. A count rate of the impedance counter is a function of the impedance of the electronic circuitry due to the fact that oscillation frequency generated by the exciter is also a function of the impedance of the electronic circuitry. The sensor also includes an impedance register storing the binary count value from the impedance counter, wherein after the impedance counter data is transferred into the impedance register, the data is referred to as impedance data. The sensor also includes a reference oscillator monitoring count rate of the impedance counter and a sensor evaluation system comparing the impedance value to threshold values to determine if a significant change has occurred. When changes have occurred this is indicative of abnormal behavior and may be indicative of tampering relating to the evaluation of the electronic circuit for the purpose of reverse engineering.
Core Innovation
The invention describes a sensor system for protecting products and technology from reverse engineering by detecting attempts to probe electronic circuitry. The system includes an impedance sensor that detects interaction of probe devices with the electronic circuitry for the purpose of reverse engineering, and the impedance sensor is completely integrated inside the integrated circuit and implemented using a programmable logic device.
The impedance sensor includes an exciter that causes an oscillation that is a function of the exciter and impedance of the electronic circuitry. The exciter is linked to an impedance counter such that a count rate of the impedance counter is a function of the impedance of the electronic circuitry due to oscillation frequency being a function of the impedance, and a binary count value from the impedance counter is transferred into an impedance register and referred to as impedance data.
A sensor evaluation system compares the impedance value to threshold values to determine if a significant change has occurred, and when changes have occurred this is indicative of abnormal behavior and may be indicative of tampering relating to the evaluation of the electronic circuit for the purpose of reverse engineering. In further embodiments, the sensor includes a ring oscillator, a tri-state buffer, and a function multiplexer controlling enablement of the exciter.
The invention also applies the impedance concept to printed circuit board circuit traces by measuring and monitoring characteristic impedance of multiple circuit traces, with the integrated circuit conductively connected to multiple circuit traces on the printed circuit board.
Claims Coverage
The independent claims cover core inventive features comprising impedance-dependent oscillation, impedance counting into an impedance register as impedance data, monitoring by a reference oscillator, and evaluation by comparing to threshold values to indicate abnormal behavior and tampering. Across the independent claims, the main inventive features are fully integrated impedance sensing in a programmable logic device, comparator-based low/high limit threshold logic, dual use I/O, tri-state buffer and function multiplexer control, ring oscillator implementation, and printed circuit board trace characteristic impedance monitoring.
Programmable logic device integrated impedance sensor for reverse engineering detection
An integrated circuit including an I/O pin, the integrated circuit being a programmable logic device including an impedance sensor and electronic circuitry in communication with the I/O pin, wherein the impedance sensor is completely integrated inside the integrated circuit and is implemented using the programmable logic device, and the impedance sensor detects interaction of probe devices with the electronic circuitry for the purpose of reverse engineering.
Exciter-driven oscillation whose oscillation frequency is a function of impedance
An exciter causes an oscillation that is a function of the exciter and impedance of the electronic circuitry, and the exciter is completely integrated inside the integrated circuit and implemented using the programmable logic device.
Impedance counter converting impedance-dependent oscillation into impedance data
An impedance counter is linked to the exciter, and a count rate of the impedance counter is a function of the impedance of the electronic circuitry. An impedance register stores the binary count value from the impedance counter, and the data is referred to as impedance data.
Reference oscillator monitoring of the impedance counter count rate
A reference oscillator monitors count rate of the impedance counter.
Threshold comparison indicating abnormal behavior and possible tampering
A sensor evaluation system compares the impedance value to threshold values to determine if a significant change has occurred, and when changes have occurred this is indicative of abnormal behavior and may be indicative of tampering relating to the evaluation of the electronic circuit for the purpose of reverse engineering.
First and second comparator low/high limit threshold evaluation logic
The sensor evaluation system includes a first comparator and a second comparator, with the second comparator comparing the impedance value with a threshold value stored in a low limit register and the first comparator comparing the impedance value to a high limit threshold value stored in a register.
Dual use I/O pin and programmable logic device integrated impedance sensing
A programmable logic device based integrated circuit includes a dual use I/O pin, an impedance sensor, and electronic circuitry in communication with the dual use I/O pin, wherein the impedance sensor is completely integrated inside the integrated circuit and detects interaction of probe devices with the integrated circuit for the purpose of reverse engineering.
Tri-state buffer and function multiplexer controlling enablement of the exciter
The sensor includes a tri-state buffer and a function multiplexer linked to the exciter and controlling enablement of the exciter.
Ring oscillator implementation for impedance measurement
The sensor includes a ring oscillator.
Printed circuit board trace characteristic impedance measurement using an exciter and impedance counter
An integrated circuit formed upon a printed circuit board includes a sensor electrically linked to electronic circuitry and conductively connected to multiple circuit traces, and the sensor measures and monitors characteristic impedance of the multiple circuit traces.
Across the independent claims, the inventive concept is an impedance sensor that produces impedance-dependent oscillation via an exciter, converts it into an impedance counter count rate, stores the resulting binary count as impedance data in an impedance register, monitors via a reference oscillator, and evaluates by comparing to threshold values to indicate significant impedance changes as abnormal behavior and may be indicative of tampering. Additional independent claim variations refine comparator-based low/high decision logic, dual use I/O and enablement control, ring oscillator implementation, and application to printed circuit board trace characteristic impedance monitoring.
Stated Advantages
Detects attempts to probe electronic circuitry for the purpose of reverse engineering.
Produces an indication of abnormal behavior when a significant impedance change has occurred.
May be indicative of tampering relating to the evaluation of the electronic circuit for the purpose of reverse engineering.
Protects products and technology from reverse engineering by detecting probe attempts.
Documented Applications
Protecting products and technology from reverse engineering by detecting attempts to probe electronic circuitry.
Monitoring characteristic impedance of multiple circuit traces on a printed circuit board as part of reverse engineering protection.
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