Performance of Secure Boot in Embedded Systems

With the proliferation of the Internet of Things (IoT), the need to prioritize the overall system security is more imperative than ever. The IoT will profoundly change the established usage patterns of embedded systems, where devices traditionally operate in relative isolation.Internet connectivity brought by the IoT exposes such previously isolated internal device structures to cyber-attacks through the Internet, which opens new attack vectors and vulnerabilities. For example, a malicious user can modify the firmware or operating system by using a remote connection, aiming to deactivate standard defenses against malware. The criticality of applications, for example, in the Industrial IoT (IIoT) further underlines the need to ensure the integrity of the embedded software. One common approach to ensure system integrity is to verify the operating system and application software during the boot process. However, safety-critical IoT devices have constrained boot-up times, and home IoT devices should become available quickly after being turned on. Therefore, the boot-time can affect the usability of a device.This paper analyses performance trade-offs of secure boot for medium-scale embedded systems, such as Beaglebone and Raspberry Pi. We evaluate two secure boot techniques, one is only software-based, and the second is supported by a hardware-based cryptographic storage unit.For the software-based method, we show that secure boot merely increases the overall boot time by 4 %.Moreover, the additional cryptographic hardware storage increases the boot-up time by 36 %

Enhancing Trust in Devices and Transactions of the Internet of Things

With the rise of the Internet of Things (IoT), billions of smart embedded devices will interact frequently.These interactions will produce billions of transactions.With IoT, users can utilize their phones, home appliances, wearables, or any other wireless embedded device to conduct transactions.For example, a smart car and a parking lot can utilize their sensors to negotiate the fees of a parking spot.The success of IoT applications highly depends on the ability of wireless embedded devices to cope with a large number of transactions.However, these devices face significant constraints in terms of memory, computation, and energy capacity.With our work, we target the challenges of accurately recording IoT transactions from resource-constrained devices. We identify three domain-problems: a) malicious software modification, b) non-repudiation of IoT transactions, and c) inability of IoT transactions to include sensors readings and actuators.The motivation comes from two key factors.First, with Internet connectivity, IoT devices are exposed to cyber-attacks.Internet connectivity makes it possible for malicious users to find ways to connect and modify the software of a device.Second, we need to store transactions from IoT devices that are owned or operated by different stakeholders.The thesis includes three papers. In the first paper, we perform an empirical evaluation of Secure Boot on embedded devices.In the second paper, we propose IoTLogBlock, an architecture to record off-line transactions of IoT devices.In the third paper, we propose TinyEVM, an architecture to execute off-chain smart contracts on IoT devices with an ability to include sensor readings and actuators as part of IoT transactions