Body-Guided Galvanic Coupling Communication for Secure Biometric Data

In a world dominated by the wearable IoT devices, malicious security threats have become a common concern in system design. Guided by this notion, we propose a secure transmission system through body-guided channels using Galvanic Coupling (GC). The GC-method injects weak electrical current into human tissue, primarily propagating through the skin. The proposed design provides impermeability to malicious attacks, (e.g. side-channel sniffing) when sending biometric data, as the body behaves as a natural waveguide. The following contributions are: 1) the analytical formulation and empirical verification of a 3D tissue equivalent circuit model for GC-signal propagation of the human arm-wrist-palm channel; 2) the simulation study of numerous modulation schemes, drawn from the validated results of the GC-channel model; 3) the design and implementation of a transceiver prototype using optimal communication parameters (modulation, frequency, power) for transmission on a dielectrically equivalent tissue phantom; and 4) through the experimental trials, we demonstrate the eavesdropping susceptibility of the GC-signals, and similar body communication techniques, over-the-air and while in direct contact with the medium. The performance results of the GC-transceiver prototype yield a bit error rate of 10−6 with a transmit power of −2 dBm, in addition to over 7 $\times$ reduction of signal radiation outside the body compared to capacitive coupling.