Extracting a chip's key lets another device answer for it

Ping-based protocols rely on cryptographic keys stored on the chip. Tee and Happel argue that an adversary with physical access could extract these keys and so compromise location verification ⁹. They propose GPU fingerprints as a mitigation, so far tested on 24 GPUs ⁹. Brass and Aarne assume the keys are stored securely, for example in a TPM ¹.