Technical detail · Tamper evidence for verifier devices

IBM 4765. FIPS 140-2 Level 4 overall and for physical security, validated in 2011. NIST later moved the certificate to its historical list after a random-number-generator transition ². A tamper-respondent matrix monitors for intrusion and adverse conditions, with moderate and severe out-of-range temperature and voltage sensing. A hard tamper triggers active wiping of secrets: the high-speed-erase battery-backed RAM holding core secrets is erased within microseconds, and the module is zeroized and left inoperable ¹.
Batteryless PUF cover. A 140 mm × 140 mm flexPCB cover with 16 × 16 electrodes (256 sensor nodes, 128 used differentially) and 100 µm line and space, checked by an STM32F303 microcontroller. After open- and short-circuit checks pass, a key is derived from the differential capacitances, about 5.2 bits of entropy per node with 10x oversampling (about 665 bits in theory). The attacker model assumes penetrations of at least 300 µm; single 0.3 mm holes made key reconstruction infeasible; a full-cover measurement with 10x oversampling takes 384 ms; power is about 0.6 W; testing spanned −20 °C to +60 °C ⁴.
Anti-Tamper Radio. Two wideband antennas inside a metal case, measured with a vector network analyzer (2–9 GHz) or ultra-wideband transceivers (2.496–7.488 GHz). In a Dell PowerEdge 2850 over 10 days, 40 mm insertions of 1 mm needles were reliably detected; in an empty aluminium box, 16 mm insertions of needles as thin as 0.1 mm were detected. UWB transceivers cost less than US$5 ⁵.
ImpedanceVerif. An embedded network analyzer on an FPGA measures the frequency response of the power distribution network, and Wasserstein distance is used as the detection statistic ⁸.