Intrinsically Reliable and Lightweight Physical Obfuscated Keys
This work addresses tamper-resistant key storage for security applications, presenting an incremental improvement by simplifying POK designs.
The paper tackles the problem of measurement noise and correlated output bits in Physical Obfuscated Keys (POKs) by proposing two intrinsically reliable designs that eliminate the need for error correction interfaces, using lithographic process and phase change memory variability, as demonstrated through experiments and simulations.
Physical Obfuscated Keys (POKs) allow tamper-resistant storage of random keys based on physical disorder. The output bits of current POK designs need to be first corrected due to measurement noise and next de-correlated since the original output bits may not be i.i.d. (independent and identically distributed) and also public helper information for error correction necessarily correlates the corrected output bits.For this reason, current designs include an interface for error correction and/or output reinforcement, and privacy amplification for compressing the corrected output to a uniform random bit string. We propose two intrinsically reliable POK designs with only XOR circuitry for privacy amplification (without need for reliability enhancement) by exploiting variability of lithographic process and variability of granularity in phase change memory (PCM) materials. The two designs are demonstrated through experiments and simulations.