Despite the increasing interest in blockchain as a possible solution to replace centralized IoT architectures, previous work failed to provide a direct role for the sensing devices, i.e., direct interaction with the blockchain without additional components. Moreover, few studies focus on permissionless blockchains, even if it is the most secure platform for developing blockchain-based applications. This thesis presents an architecture that considers constrained sensing devices as direct actors on a public blockchain network. A public blockchain network allows the seamless inclusion of several unknown actors, and smart contracts provide a platform to develop complex IoT applications. The research followed an iterative DSR approach; designing, building, and evaluating new IT artifacts using two case studies in the agricultural IoT domain. These cases fostered two exploratory studies that diverged from the main IoT domain; however, they also provide novel contributions to blockchain-based applications. Thus, the novel architecture tackles three problems of current blockchain-based IoT systems i) constrained sensing devices as direct actors on a blockchain system, ii) permissionless blockchain networks and iii) smart contracts as an IoT application platform. Furthermore, the exploratory analyses examine two challenges of blockchain-based applications i) user experience and monetary costs and ii) data sharing and decentralized storage.

<p dir="ltr">Blockchain technology, once the backbone of Bitcoin, has burgeoned into a powerhouse of potential, signaling a revolutionary shift across various sectors, including finance, supply chains, and digital identity. This paradigm shift, which replaces trust in centralized entities with a decentralized ledger of transparency, is rapidly gaining traction among global entities. Despite the promise, blockchain's smart contract evolution has also introduced significant risks, as demonstrated by notorious breaches like the DAO hack. This research offers a dual-focused inquiry into the technological sophistication and social implications of blockchain, particularly smart contracts, assessing both their promise and their perils. It meticulously examines their design, potential vulnerabilities, and recounts sobering lessons from historical breaches.</p><p dir="ltr">To address these concerns, the study presents advanced strategies for vulnerability detection and proactive remedies, recognizing the critical need for security in our digitally convergent economy. In Chapter 3, a novel methodology is employed that uses a comprehensive dataset against advanced detection tools, aiming to address and mitigate vulnerabilities. Chapter 4 provides empirical evidence of the methodology's efficacy, underpinning a critical discussion with real-world applicability and challenges.</p><p dir="ltr">Ultimately, this paper acts as a clarion call for vigilant and innovative strides in blockchain security, emphasizing the technology's vast capabilities against the need for solidified trust. It invites the global research community to join a collaborative effort in addressing the open challenges and fostering advancements to ensure the safe expansion of blockchain technology.</p>

The perspective of procurement and supply chain management is changing dramatically; traditionally, it was seen as a support function; however, the procurement function is receiving increased attention and investment as an essential contributor to the strategic success and a business enabler. While an end-to-end digital supply chain is an opportunity as it unleashes the next level of strategic growth and involves minimal investment in infrastructure, it is still a challenge to optimize and transform. Furthermore, the recent pandemics and geopolitical disruptions of Covid-19, the Ukraine-Russian war, Brexit and the US-China trade war; have structurally changed the global economy and revealed a new risk assessment that will result in the re-introduction of buffers, boundaries across industries and a partial return to regionalization with sort of de-globalization in which existing just-in-time getting replaced by just-in-case strategy.