Hardware Security
What is the main reason hardware Trojans are hard to find with ordinary testing?
- AHardware Trojans are attached outside the chip
- BHardware Trojans destroy the test equipment
- CThey are built to activate only under extremely rare inputs or conditions (triggers) and otherwise behave like normal circuits
Show answer and explanation
Answer: C. They are built to activate only under extremely rare inputs or conditions (triggers) and otherwise behave like normal circuits
Manufacturing tests check that the designed functions work correctly. A hardware Trojan is built to activate only under conditions tests almost never produce, such as a particular 32-bit input value or a counter reaching billions, so it normally appears healthy. It may also need only a tiny number of transistors compared with billions in the whole chip, making visual detection difficult too.
- A. They hide among the circuits inside the chip.
- B. They do not destroy equipment.
- C. Correct. They trigger on conditions tests never produce.