Replacing electronic components with molecule-sized analogs or hybrids is often seen as a promising alternative to further miniaturization of conventional electronics in the effort to achieve functional nanoscale circuit elements. In this thesis, electronic transport through self-assembled networks with tunable thiolated (alkane(di)thiol and benzenedithiol) molecule-to-colloidal gold (Au) nanoparticle ratios (1:5–50:1) is studied using a combination of broad area and scanning probe microscope-based measurements. The electronic transport paths through the network can be altered by adjusting the (di)thiol molecule–gold nanoparticle ratio and/or type of molecules in the network. Resistance can be controllably tuned by several orders of magnitude (~105 to 1011 ohms for the Au-thiolated structures studied). Two-terminal current–voltage (I-V) measurements of the Au-thiolated networks display linear behavior at low bias. High bias measurements in case of benzenedithiol networks show nonlinear negative differential resistance (NDR) and hysteresis behavior for different benzenedithiol concentrations, which can be attributed to a combination of field-assisted tunneling and charge trapping occurring in the nanoscale networks. Circuit simulations that account for different network morphologies, tunable via molecule-to-nanoparticle ratio, and defects show good agreement with the experiment and provide a guide to engineer network properties using different molecules. In addition, electronic transport properties of nanoscale networks, which are composed of Au metal clusters interconnected with thiolated molecules (benzene/alkanedithiol) and connected in linear chains and branched extended networks, are examined via first-principles density functional theory-based simulations. Calculated I-V characteristics of the metal-molecular networks exhibited nonlinearities and rectification with NDR peaks that became more pronounced with increasing chain length. The transmission spectra of the linear chains and branched networks showed an increase in the number and width of transmission peaks near the Fermi energy, as the structures were extended, indicating enhanced transmission. Peak-to-valley current NDR ratios as large as ~ 500 and rectification ratios of ~ 10 (0.25 V) were shown for linear and branched circuit elements, respectively, illustrating how charge transport through molecular-scale devices could be controlled with precision by modifying the structure and geometry of molecule-nanoparticle networks. These experimental and simulation results are utilized to propose molecular-scale circuits in applications such as memory, switching, and hardware security. The metal nanoparticle molecular electronic networks presented in this thesis provide an avenue for engineering electronics at the molecular level. / Graduate

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<p dir="ltr">The world is increasingly dependent on cyber-physical systems (CPSs), e.g., robotic vehicles (RVs) and industrial control systems (ICSs). CPSs operate autonomously by processing data coming from both “cyberspace”—such as user commands—and “physical space”—such as sensors that measure the physical environment in which they operate. However, even after decades of research, CPSs remain susceptible to threats from attackers, primarily due to the increased complexity created by interaction with cyber and physical space (e.g., the cascading effects that changes in one space can impact on the other). In particular, the complexity causes two primary threats that increase the risk of causing physical damage to RVs: (1) logic bugs causing undesired physical behavior from the developers expectations; and (2) physical sensor attacks—such as GPS or acoustic noise spoofing—that disturb an RV’s sensor readings. Dealing with these threats requires addressing the interplay between cyber and physical space. In this dissertation, we systematically analyze the interplay between cyber and physical space, thereby tackling security problems created by such complexity. We present novel algorithms to detect logic bugs (PGFuzz in Chapter 2), help developers fix them (PGPatch in Chapter 3), and test the correctness of the patches attempting to address them (PatchVerif in Chapter 4). Further, we explain algorithms to discover the root causes and formulate countermeasures against physical sensor attacks that target RVs in Chapter 5.</p>

<p dir="ltr">Sensing and communication circuits and systems are crucial components in various electronic devices and technologies. These systems are designed to acquire information from the surrounding environment through sensors, process that information, and facilitate communication between different devices or systems. It plays a vital role in modern electronic devices, enabling them to collect, process, and exchange information to perform various functions in applications such as IoB (Internet of Body), healthcare, hardware security, industrial automation, and more.</p><p dir="ltr">This work focuses on innovations in sensing and communication circuits spanning two independent application areas – human body communication and hardware emanations security.</p><p dir="ltr">First, an ultra-low power ECG monitoring system is implemented to perpetually power itself using Thermoelectric Generator (TEG) to harvest body energy while securely transmitting sensed data through on-body communication, achieving closed-loop operation without external charging or batteries. Custom circuits allow demonstrated feasibility of self-sustaining wearables leveraging Human Body Communication’s advantages.</p><p dir="ltr">Second, investigations reveal vulnerabilities introduced when repairing broken cables, with unintended monopole antennas boosting electromagnetic emissions containing signal correlations. Experiments characterize long-range detection regimes post-repair across USB keyboard cables. Further circuit and structural innovations provide localized shielding at repair points as a potential mitigation. Advancements offer contributions in understanding hardware emission security risks to inform protection strategies.</p><p dir="ltr">The two separate research work demonstrate specialized circuits advancing the state-of-the-art in sensing and communication for wearable body-based systems and hardware security through greater awareness of vulnerabilities from unintended emissions.</p><p><br></p>

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This thesis covers the security testing of a system with connected devices. In a world with an ever-growing number of connected devices, it is crucial to be mindful of the consequences unprotected systems can cause. The thesis aim to shine light on the issues of not having sufficient security measures in place. The test target was a system with a battery charger, gateway and cloud service. The testing was done with two different approaches, penetration testing and threat modelling, covering different parts of the system. Only a small fraction of the system was exploited in the report and overall the security was deemed to be alright. The main vulnerabilities found were that the username and password were found unencrypted when attempting to log into the gateway. The traffic between the battery charger and the gateway was also unencrypted and possibly vulnerable to replay attacks. For evaluation of the penetration testing and threat modelling there were found to be advantages and disadvantages to both methods. For a thoroughly analysis of the methods it would have needed further investigation. The system itself has potential for valuable findings with further investigations as well. / Denna rapport inkluderar säkerhetstestning av ett system med uppkopplade enheter. Antalet uppkopplade enheter (Sakernas Internet) runt om i världen fortsätter att växa med hög hastighet. Det är av stor vikt att se till att enheterna i dessa system har de säkerhetsåtgärder som krävs. Att belysa detta problem är ett utav målen med denna rapport. I rapporten testas ett batteriladdarsystem med tillhörande gateway och cloud-tjänst. Testen utfördes med två olika metoder, penetrationstest och hotmodellering, uppdelat på två olika delar av systemet. På grund av de begränsningar som fanns kunde endast en liten del av systemet testas och exploateras. Till största del ansågs säkerheten vara okej. De främsta sårbarheterna som hittades var bland annat okrypterade  användarnamn och lösenord vid försök att logga in på gatewayen. All traffik mellan batteriladdaren och gatewayen var orkypterad och med stor risk för att inte kunna stå emot en replayattack.  Utvärdering av de två metoderna som användes konstaterades för och nackdelar med båda metoderna. För att kunna göra en ordentlig jämförelse av metoderna skulle det behövas en djupare undersökning. Det finns även stort värde i en vidare undersökning av systemet.