Hardware Security

What is the advantage of using a PUF for key storage?

  1. AUsers can freely choose the key value
  2. BThe key always remains in memory at power-off
  3. CThe key need not be written in non-volatile memory and is regenerated only when used, so it is hard to extract even if the chip is analyzed
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Answer: C. The key need not be written in non-volatile memory and is regenerated only when used, so it is hard to extract even if the chip is analyzed

Keys written in flash or eFuses are targets for attacks that open the chip and read storage directly. With a PUF, the key is regenerated from the chip's physical properties each time it is used and is stored nowhere while power is off. Physically tampering with the chip to read the PUF also alters the very variation it depends on, making extraction even harder.

  • A. The value is set by variation and cannot be chosen.
  • B. Not storing it is precisely the advantage.
  • C. Correct. With power off, the key is stored nowhere.
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More Hardware Security questions

  1. What property does an SRAM PUF exploit?
  2. Why is error correction (such as helper data) combined with PUFs when deriving keys?
  3. Which describes a true random number generator (TRNG) built into a chip?
  4. What can happen if poor-quality, predictable random numbers are used to generate cryptographic keys?
  5. Which describes a hardware Trojan?