Platform for digital voice communication with channel-based key generation

This paper proposes a novel method for the integration of channel-based key generation in a real-time digital voice communication system. For this purpose, a specific hardware platform was developed. To obtain the keys for the cipher, channel-based key generation is used to generate identical keys on both sides of the channel, based on the unique reciprocal channel characteristics. Hamming code key reconciliation drastically reduces the probability of remaining key errors, while a cyclic redundancy check (CRC) is used as a final checking mechanism. As a proof of concept, the generated key is used to encrypt as well as decrypt the audio by means of an XOR operation at both sides of the link. Several measurements were performed, showing that new keys are continuously being formed and replaced. Additional measurements also create more insight into the key update rate and key entropy for different parameter settings in the algorithm

Wearable coupled-quarter-mode SIW antenna platform with hybrid kinetic and ambient-light energy harvesting

Abstract As key enablers for smart fabric interactive textile (SFIT) systems, textile antenna systems and platforms need to be energy-efficient, low-profile and should guarantee a stable wireless body-centric communication link. Using multiple energy harvesters on and in the antenna platform is highly recommended to enable autonomous SFIT systems. Different sensors could be added to the system for monitoring the environmental and/or biophysical parameters of rescue workers, military personnel, and other safety workers. Therefore, a wearable coupled-quarter-mode (coupled-QM) substrate-integrated waveguide (SIW) antenna with optimally, seamlessly integrated hybrid kinetic and ambient-light energy harvesters is proposed. Two QM cavities are coupled via a non-resonant slot to create a compact antenna covering the [2.4; 2.4835] GHz Industrial, Scientific and Medical (ISM) band. The antenna platform fully consists of textile materials, being protective rubber foam and copper taffeta, enabling its unobtrusive integration into protective clothing. A novel, compact way of deploying a kinetic energy harvester inside the substrate, combined with flexible power management electronics on the antenna feed plane and a flexible ambient-light photovoltaic cell on the antenna plane, is proposed. The integrated antenna platform exhibits a measured impedance bandwidth of 307 MHz, a radiation efficiency of 88.57% and maximum gain of 3.74 dBi at 2.45 GHz. Wearing the antenna platform around a person’s wrist resulted in an average harvested power of 229.8 µW when walking in an illuminated room

Platform for multi-user channel-based encryption of speech communication with AES on 2.45 GHz

This paper outlines a hardware platform for half-duplex, real-time encrypted digital speech communication on 2.45 GHz. The platform is based on a STM32F415 MCU with a low power ADF7242 transceiver for wireless communication. The Advanced Encryption Standard (AES) Electronic Code Book encryption scheme is performed on the transmitted packets with symmetrically generated channel-based keys. Encryption keys of 128-bit are obtained, based on the unique reciprocal channel characteristics of the employed link. Key reconciliation is applied by means of a Hamming code and a cyclic redundancy check (CRC) to correct key mismatch. A multi-user system is introduced by splitting voice key distribution and speech communication into different abstraction layers. Measurements reveal a maximum communication range of 400 m without significant packet loss. A high key entropy of 0.94 bit is established with a packet rate of 167 packets/s and a key bit generation delay of four received signal strength (RSS) measurements