‘Suicide chips’ could boost electronics security

US researchers have developed microchips with a feature that combines anti-counterfeit with a function that causes them to self-destruct if an attempt is made to compromise them.

The team from the University of Vermont presented the concept at the IEEE International Solid-State Circuits Conference (ISSCC), explaining that it is based on physically unclonable functions (PUFs) which can create a unique ‘fingerprint’ for each unique chip made.

The IEEE Spectrum newsletter reports that the PUFs have a pair of so-called ‘circuit suicide’ methods, which both exploit voltage in the lines connecting to the encryption key’s bit-generating circuits.

“One effect is to boost in current in the circuit’s longest interconnects. That leads to electromigration, a phenomenon where current in very narrow interconnects literally blows metal atoms out of place, leading to voids and open circuits,” says the article.

The second method causes a short circuit by subjecting transistors meant to operate at less than 1 volt to 2.5 volts, creating an ageing effect called time-dependent dielectric breakdown.

The team, led by Vermont’s Eric Hunt-Schroeder and assisted by chip specialist Marvell Technology, was motivated to make the circuit suicide technology by reports that researchers had been able to clone SRAM-based PUFs using a scanning electron microscope.

It could also be used to disable chips when an electronic device comes to the end of its life, preventing them from being counterfeited and returned to the market.

It has been estimated that the counterfeit chip market value was around $75bn in 2019, with falsified components ending up in $169bn worth of electronic products.