Strong Keys from Heat‑Proof Diamond

Scientists have found a way to make secure encryption keys that keep working even when the temperature jumps from normal room levels up to 700 °C. The trick uses a special kind of diamond called nitrogen‑incorporated ultrananocrystalline diamond, or n‑UNCD for short. Inside this material are tiny grain boundaries rich in defects that can be read as random numbers, a perfect source of “entropy” for cryptography. Because diamond is incredibly stable and chemically inert, the random numbers it produces stay reliable after long periods at extreme heat. In tests, the n‑UNCD film produced keys that survived 54 hours at 700 °C and also withstood repeated cycles between room temperature and the same high heat for 48 hours. The quality of these keys was checked against several industry standards: the bits were evenly distributed, had high entropy, and showed large Hamming distances from each other.

They also passed the NIST SP 800‑90B tests, which are a gold standard for random number generators. Researchers also proved that the keys cannot be easily predicted or manipulated, even if an attacker tries to bias the power supply or uses a machine‑learning model based on Fourier analysis. The keys’ resilience comes from the fact that the n‑UNCD layer does not let metal atoms spread into it, as confirmed by energy‑dispersive X‑ray spectroscopy. Raman spectroscopy further showed that the diamond’s bonding structure does not change under heat, keeping its defect network intact. Overall, this breakthrough shows that n‑UNCD films could become the backbone of secure hardware for future space probes, geothermal plants, and nuclear facilities where temperatures routinely exceed 200 °C.

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