Alan J. Michaels

Analysis of parasitic effects of sodium hydroxide (NaOH) electrolyte on liquid-metal monopole antennas

Liquid metal alloys are being researched as a safe alternative to mercury in many different applications. One of these applications is using the liquid metal to form a reconfigurable antenna that allows changing frequency, beam steer, or polarization in real-time by injecting or retracting the liquid metal. Due to the formation of an oxidation layer on top of the liquid metal, researchers have been using an electrolyte to corrode this layer. This letter will analyze the effect this electrolyte has on the return loss of the antenna. Preliminary results show the electrolyte changes the effective length of the antenna, causing it to have a minimum return loss value at lower frequencies than predicted from the metal height alone.

PRNG sequence combination techniques via Galois extension fields

The generation of pseudorandom number sequences can be achieved in a variety of ways, with the most secure methods generally requiring substantial processing to generate. Other pseudorandom number generation (PRNG) methods accept a compromise between processing power and security by mixing two independent, but less secure, PRNG outputs with each other. This paper presents a generalized mixing method for any number of PRNG streams using Galois Extension Field techniques that achieves maximal entropy when conditioned on any individual input, making the reverse engineering of the combined result exceedingly difficult. In addition to this basic mixing method, enhanced adaptations are presented that further improve the output while using simple bit-level statistical operators.

Framework for Evaluating the Severity of Cybervulnerability of a Traffic Cabinet

The increasing connectivity in transportation infrastructure is driving a need for additional security in transportation systems. For security decisions in a budget-constrained environment, the possible effect of a cyberattack must be numerically characterized. The size of an effect depends on the level of access and the vehicular demand on the intersections being controlled. This paper proposes a framework for better understanding of the levels of access and the effect that can be had in scenarios with varying demand. Simulations are performed on a simplistic corridor to provide numerical examples of the possible effects. The paper concludes that the possibility of some levels of cyberthreat may be acceptable in locations where traffic volumes would not be able to create an unmanageable queue. The more intimate levels of access can cause serious safety concerns by modifying the settings of the traffic controller in ways that encourage red-light running and accidents. The proposed framework can be used by transportation professionals and cybersecurity professionals to prioritize the actions to be taken to secure the infrastructure.

Tire Pressure Monitoring System Sensor Radio Frequency Measurements for Privacy Concerns

Since the National Highway Traffic Safety Administration mandated the incorporation of tire pressure monitoring systems (TPMSs) in all newly produced passenger vehicles, most vehicle manufacturers have adopted direct pressure measurement. Direct TPMS sensors embedded in each tire require a wireless radio frequency (RF) communications link that broadcasts tire status to the vehicle once per minute from each tire when at speed. Each TPMS message communicates benign information that includes pressure and temperature as well as a static unique identifier that may be exploited, which raises concerns about privacy and spoofing. To focus on concerns related to the TPMS-RF interface, vehicle motion simulations were integrated with live propagation modeling measurements from three classes of passenger vehicles: subcompact car, full-size sedan, and full-size pickup. The RF link and channel models for this TPMS interface with the vehicle resulted in surprisingly long ranges away from the vehicle for the radiation of the unique identifiers. A TPMS sensor redesign could use the proposed RF channel propagation measurements to change the directions of signal propagation while reducing battery consumption by the TPMS sensor (which is affected primarily by RF transmission).

Tire Pressure Monitoring System encryption to improve vehicular security

Vehicles are increasingly wirelessly connected and each wireless connection is a potential cyber threat surface. Many of these wireless communications are related to the infotainment systems and are optional, some are not. Since 2008, when the U.S. government mandated the need for real-time tire pressure diagnostics, automotive manufacturers have inserted Tire Pressure Monitoring System (TPMS)-based devices in all vehicles sold domestically. These sensors are divided into “direct” and “indirect” TPMS based on the mechanisms used to observe the tire pressure, temperature, and other characteristics; while marginally more expensive, most such systems are directly embedded in the tire to achieve the diagnostics requirements stated in National Highway Traffic Safety Administration [1], [2], necessitating a wireless communications link back to a cars Controller Area Network (CAN) bus and engine control unit (ECU). In this paper, we seek to evaluate the cyber-security of that TPMS wireless communications interface, proposing and evaluating the viability of incorporating a more secure TPMS protocol that takes advantage of simple linear feedback shift register (LFSR)-based message encryption. The proposed models were designed and implemented in both a Universal Serial Radio Peripheral (USRP) N210 software defined radio (SDR) testbed that replicates each side of the TPMS link; the resulting capabilities were also simulated on an inexpensive Arduino platform to demonstrate cost realism in the threat to the TPMS system.

Improved RNS-based PRNGs

In developing pseudorandom number generation mechanisms for low-power systems like the Internet of Things (IoT), there exists a large tradeoff between computational complexity and the resulting security enabled by the generator. For most communications applications, the use of any PRNG stream must be performed in a synchronizable, and sometimes invertible, fashion. This paper focuses on improvements to prior residue number space (RNS)-based PRNGs, configured to support extremely low-power IoT applications via internal dynamics like switching between PRNG components, simpler permutation-based mappings as opposed to pre-defined polynomials, dynamic indexing processes for improved multiple access operation, and computationally efficient sequence combination techniques. While similarly scalable to applications of prior RNS-based PRNGs, simulation and hardware prototyping results on an MSP430 and Altera FPGAs (Cyclone V and Arria 10) equally validate the suitability of the proposed PRNG techniques for microprocessor-level low-power implementations like industrial IoT.

Measuring coupled signals on active ship-based communication systems

Ships present a unique challenge for measuring the amount of coupled energy to a communication system. This paper proposes a coupled energy measurement system that takes into account multiple networked communication systems, limited space, and non-invasive requirements to make a ship-based communication system easier to study. The proposed measurement system would be mobile, non-invasive, and allow for multiple systems to be measured in unison.

Enhanced TPMS security through acceleration timed transmissions

Tire Pressure Monitoring Systems (TPMS) offer real-time diagnostics of the status of a vehicles tires via a wireless communications link back to the vehicle. These links, which provide data, mandated by the NHTSA, generally possess low security/low privacy, leading to a demonstrated potential for spoofing attacks or tracking a person/vehicle through the unencrypted emission of the tires unique identifier. Due to the radiation pattern of the valve stem (used as the TPMS antenna), much of the signal is directed away from the vehicle. This paper investigates the possibility of decreasing the required signal strength by using the already existing accelerometer on the TPMS to detect the angle of the wheel and to transmit data at an optimal wheel orientation. This paper shows that the received signal strength at the vehicle receiver can differ by up to 20 dB between the best and worst orientations and provides a low computation option for estimating the angle of the wheel. Implementation of this algorithm or a similar algorithm would provide better battery life and better security for the TPMS while keeping cost the same.

Design and analysis of dual helix liquid metal antenna

The goal of this paper is to expand on previously researched Eutectic Gallium-Indium (EGaIn) alloy liquid metal antennas to create an antenna that can change both polarization and frequency to meet the users needs. This concept is described through analytical models of helix antennas, simulations performed in FEKO, and measured results of a proof-of-concept dual frequency L-band GPS-focused hardware model. Although ongoing work is being performed to more efficiently feed this proof-of-concept liquid metal antenna, the overall realized gain of the helix aligned well with theoretical models.

Design and analysis of two-dimensional parasitic liquid metal monopole array

The goal of this paper is to expand from previously researched liquid metal linear array models into a dynamically driven two dimensional liquid metal array. Simulations were performed using FEKO to prove the concept that a multi-dimensional array will provide the user more control over the direction of the main beam and also the direction of the nulls, making the resulting array useful for spatially tracking signals and mitigating interference. A proof-of-concept hardware model of the 2D array antenna was built and tested in the context of a dual frequency dual frequency GPS antenna (L1, L2/L5) with results found comparable to simulation. Since the antennas are made from liquid metal, these results make it possible for the user to change the parasitic elements within the 2D array from negligible (height of zero) to directors, to reflectors, or back with the use of a syringe or pump. This spatially adaptable antenna also benefits from the use of a single digitizer chain, offering a concrete alternative for anti-jam GPS antennas as the technology matures.