Identification of PPG Measurement Sites Toward Countermeasures Against Biometric Presentation Attacks

In this study, we propose a countermeasure against a presentation attack on a photoplethysmogram (PPG)-based biometric authentication system. The countermeasure detects fake PPG signals by identifying PPG measurement sites on the body based on the difference between PPG waveforms recorded at genuine measurement and non-genuine sites without adding other sensing components. In an experiment, we computed the correlation coefficients as the similarity indices between PPG waveforms using two datasets, i.e., PPG signals recorded at multiple measurement sites on participants and mapped signals to generate fake signals for authentication. We then evaluated the proposed countermeasure using the feature values extracted from the PPG signals to identify the measurement sites on the body. The experimental results indicated that the identification of measurement sites as a countermeasure operated successfully for both PPG datasets, regardless of the presence or absence of waveform mapping, and exhibited an identification accuracy of more than 90 % regardless of the elapsed time.