Institute for Communication Technologies and Embedded Systems

pHGen: A pH-Based Key Generation Mechanism Using ISFETs

Moussavi, E.Šišejković, D. ,  Brings, F. ,  Kizatov, D. ,  Singh, A. ,  Xuan , T. V. ,  Ingebrandt, S. ,  Leupers, R. ,  Pachauri, V. ,  Merchant, F.
Book Title:
IEEE International Symposium on Hardware Oriented Security and Trust (HOST)
accepted for publication
Jun. 2022
Digital keys are a fundamental component of many hardware- and software-based security mechanisms. However, digital keys are limited to binary values and easily exploitable when stored in standard memories. In this paper, based on emerging technologies, we introduce pHGen, a potential-of-hydrogen (pH)-based key generation mechanism that leverages chemical reactions in the form of a potential change in ion-sensitive field-effect transistors (ISFETs). The threshold voltage of ISFETs is manipulated corresponding to a known pH buffer solution (key) in which the transistors are immersed. To read the chemical information effectively via ISFETs, we designed a readout circuit for stable operation and detection of voltage thresholds. To demonstrate the applicability of the proposed key generation, we utilize pHGen for logic locking---a hardware integrity protection scheme. The proposed key-generation method breaks the limits of binary values and provides the first steps toward the utilization of multi-valued voltage thresholds of ISFETs controlled by chemical information. The pHGen approach is expected to be a turning point for using more sophisticated bio-based analog keys for securing next-generation electronics.