Shovan Maity

Adaptive interference rejection in Human Body Communication using variable duty cycle integrating DDR receiver

Connected smart wearable devices are becoming increasingly popular with the advent of cheap, miniaturized, ultra-low-power computing and communication. Human Body Communication (HBC) is emerging as an alternative to Wireless Body Area Network (WBAN) for communication among these devices, as it provides higher energy-efficiency and security. One of the biggest bottleneck of HBC is the interference picked up due to the human body antenna effect, with Signal to Interference Ratio often worse than −20dB. An interference robust integrating dual data rate (DDR) receiver is introduced which can adapt itself to changing interference conditions and provide high interference rejection by Pulse Width Modulation of integration clock, thus dynamically changing its duty cycle. The theory, architecture of the receiver is developed along with the adaptation algorithm to train the receiver to find the optimum duty cycle of operation. System-level simulations show >20 dB of rejection even in presence of variable interference frequencies.

Wearable health monitoring using capacitive voltage-mode Human Body Communication

Rapid miniaturization and cost reduction of computing, along with the availability of wearable and implantable physiological sensors have led to the growth of human Body Area Network (BAN) formed by a network of such sensors and computing devices. One promising application of such a network is wearable health monitoring where the collected data from the sensors would be transmitted and analyzed to assess the health of a person. Typically, the devices in a BAN are connected through wireless (WBAN), which suffers from energy inefficiency due to the high-energy consumption of wireless transmission. Human Body Communication (HBC) uses the relatively low loss human body as the communication medium to connect these devices, promising order(s) of magnitude better energy-efficiency and built-in security compared to WBAN. In this paper, we demonstrate a health monitoring device and system built using Commercial-Off-The-Shelf (COTS) sensors and components, that can collect data from physiological sensors and transmit it through a) intra-body HBC to another device (hub) worn on the body or b) upload health data through HBC-based human-machine interaction to an HBC capable machine. The system design constraints and signal transfer characteristics for the implemented HBC-based wearable health monitoring system are measured and analyzed, showing reliable connectivity with >8× power savings compared to Bluetooth low-energy (BTLE).

High efficiency power side-channel attack immunity using noise injection in attenuated signature domain

With the advancement of technology in the last few decades, leading to the widespread availability of miniaturized sensors and internet-connected things (IoT), security of electronic devices has become a top priority. Side-channel attack (SCA) is one of the prominent methods to break the security of an encryption system by exploiting the information leaked from the physical devices. Correlational power attack (CPA) is an efficient power side-channel attack technique, which analyses the correlation between the estimated and measured supply current traces to extract the secret key. The existing countermeasures to the power attacks are mainly based on reducing the SNR of the leaked data, or introducing large overhead using techniques like power balancing. This paper presents an attenuated signature AES (AS-AES), which resists SCA with minimal noise current overhead. AS-AES uses a shunt low-drop-out (LDO) regulator to suppress the AES current signature by 400x in the supply current traces. The shunt LDO has been fabricated and validated in 130 nm CMOS technology. System-level implementation of the AS-AES along with noise injection, shows that the system remains secure even after 50K encryptions, with 10x reduction in power overhead compared to that of noise addition alone.

Secure Human-Internet using dynamic Human Body Communication

Continuous miniaturization and cost reduction of unit computing has led to the prolific growth of smart wearable devices. These devices, present on and around the human body, form a complex network known as the Human-Intranet. The Human-Intranet is typically connected through Wireless Body Area Network (WBAN). However, Human Body Communication (HBC) has recently emerged as an energy-efficient and secure alternative that uses the human body as the communication medium. Human-human, human-machine interaction creates dynamic HBC channels, which allow these Human-Intranets to interact with each other forming a Human-Internet. In this paper, we present the concept and demonstration of Secure Human-Internet using dynamic HBC. We highlight important applications of Human-Internet and discuss the architecture of a wearable Human-Internet device capable of communicating through inter-body dynamic HBC. A custom-built hardware prototype is used to demonstrate for the first time information exchange (e.g. business card) during handshaking. Dynamic signal transfer characteristics during inter-body communication through handshake between two individuals wearing such devices are measured and analyzed. The effects of data transmission rate, handshake posture on the HBC based inter-body communication is explored to demonstrate its effectiveness and limitations under varying realistic scenarios. The specific COTS based HBC implementation shows > 8× better energy efficiency compared to the Bluetooth implementation.