EDITOR’S CHOICE CORE SUPPLY ANALOG SUPPLY


ANALOG INPUT


Bandgap Ref Selector


+ -


DIGITAL INPUTS


Level Shifters Ref Selector


+ -


NEGATIVE DETECTOR


POSITIVE DETECTOR


Latch & Test Logic


Level Shifters


DIGITAL OUTPUTS


MONITOR OUTPUTS


agileVGLITCH system overview


Reference selectors These reference selectors provide configurable input voltages to the programmable comparators to allow the glitch side to be adjusted. These also allow the thresholds to be adjusted if the core is subject to Dynamic Voltage and Frequency Scaling (DVFS), for example.


Control and test logic and level shifters


From the output of the comparator, the control logic provides the following functions:


• Control of enables based on digital inputs • Latching of momentary events on the comparator outputs


• Disabling the outputs during test mode • 3-way majority voting on latched outputs.


Optional ADC


An optional SAR ADC can be used to measure the exact value of the supply, which can be used for ongoing monitoring of lifetime issues or performance degradation.


The best way to understand hacker attacks and how to prevent them is to look at some example applications.


An obvious target is an electronic security lock. An SCA is used to enter the debug mode of the device that then enables all the details of authorised keys to be read. With those details, an intruder can have access and, worse, the audit trail of which key was used is worthless. agileVGLITCH is able to detect voltage glitch events and records them as


Agile Analog has created a counter measure IP block that can be included into an SoC design specifically to detect when such an attack is happening so that the SoC can take appropriate counter measures.


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suspicious activity. Once repowered, the lock is able to report to the cloud that nefarious activity was suspected with date and time implicating the nefarious party.


”


Uploading new firmware that has a hidden feature built into it is a very stealthy hack. For example, replacing the firmware of a security camera that then also streams the video to the hacker.


This is done by the SCA allowing the hacker to bypass the standard boot- signing sequence, reset the security key to a known value, and then reflash unauthorised firmware. agileVGLITCH is able to detect voltage glitch events and prevents unauthorised code from being installed on the device to reset the boot keys. In addition, the device is able to report to the user and server that it was not new out of the box so that the user can replace it. agileVGlitch can also be used for performance degradation in, for example, cars. Perhaps a supply regulator has a small


manufacturing fault such that an increased power supply resistance is seen over time and this is exacerbated at moments of high load causing the voltage to drop to below acceptable safe levels.


agileVGLITCH is able to detect ongoing voltage degradation over time and that, at times, this can spike close to spec limits. This is reported by the system back to the car manufacturer who can identify the fault and recall cars in priority order to have this fixed ahead of a fault causing an accident. The automotive supplier may also be able to remotely fix cars through a software patch to increase the supply voltage on cars that have been identified early as having a potential issue.


Conclusion


There are a very wide variety of exploits available for modern devices. Although many current vulnerabilities are software related, as these are patched, the physical hardware vulnerabilities will become an increasingly important attack vector. More notable than this, although devices can be remotely patched for software vulnerabilities, hardware vulnerabilities usually require a hardware replacement to address them – thus leaving vulnerabilities present in millions of devices. The combination of Agile Analog’s SCA monitors allows protection against many vulnerabilities and attack vectors, and, at very low silicon cost, can prevent exploits that can have significant and long-running implications.


OCTOBER 2023 | ELECTRONICS FOR ENGINEERS 21


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