Chypothermia: Clock Freezing for Static Side-channel Attacks
Chypothermia attack uses cryogenic cooling to disable clock and voltage sensors, evading detection and blocking key zeroization on OpenTitan root of trust.
Chypothermia is a static side-channel attack that exposes chips to cryogenic temperatures, disrupting on-chip mixed-signal components to disable the clock sensor, clock generation circuit, and voltage sensors without electrical tampering. Combined with Chypnosis (IEEE S&P 2026), it halts the clock while evading temperature-based anomaly detection. It was implemented on multiple FPGA/SoC platforms and applied to the OpenTitan root of trust's alert handler, evading detection and preventing key zeroization. The authors also propose an FPGA-compatible self-heating sensor as a countermeasure.
- Cryogenic cooling disables clock and voltage sensors without electrical tampering
- Chypothermia plus Chypnosis halts clocks while evading temperature-anomaly detection
- Demonstrated against OpenTitan alert handler, preventing key zeroization
- Proposes FPGA-compatible self-heating sensor as countermeasure
From the original article
1 min read at arxiv.orgStatic side-channel attacks, which exploit halted-clock conditions to extract sensitive information, pose an increasing threat to chip security. To counter these attacks, various defenses have been proposed that monitor for abnormal clock behavior and trigger the clearing of sensitive data when clock anomalies are detected.
By Fatemeh Khojasteh Dana · arxiv.org
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