Smart contracts have become the backbone of decentralized ecosystems, managing billions of dollars in assets across applications ranging from Decentralized Finance (DeFi) to digital governance. Given the immutable and autonomous nature of blockchains, the security of these contracts is paramount. A single vulnerability can lead to catastrophic and irreversible financial losses. However, despite these high stakes, a significant gap exists in understanding how developers utilize exception-handling mechanisms to enforce correctness and the specific types of logic flaws that arise from their misuse. This thesis aims to enhance smart contract security through comprehensive studies, beginning with an empirical characterization of defensive programming practices, followed by a systematic analysis of associated faults, and finally, the proposal of a novel vulnerability detection framework. It consists of the following three studies. The first study focuses on the fundamental safeguards of contract logic: state-reverting state-ments (i.e., require, revert, and throw). While these statements serve as the principal mechanisms for exception handling in Solidity, there is a lack of empirical understanding regarding their prevalence and usage patterns in the wild. To address this, the study conducts the first empirical study across thousands of real-world contracts. The results reveal that these statements are pervasive, appearing even more frequently than general-purpose if statements. The analysis further demonstrates that developers primarily use these statements to perform seven types of authority verification and input validity checks. This study establishes an understanding of how developers intend to secure contract logic. The second study investigates the landscape of faults arising from the improper use of these state-reverting statements. Although developers rely on these statements for security, incorrect implementation results in subtle bugs that traditional testing often misses. To understand these failures and benchmark detection capabilities, this study constructs the first comprehensive dataset of 320 real-world faults, curated from open-source project histories and security audit reports Through manual analysis, the study derives a taxonomy of 17 distinct fault types and distills 12 common fixing strategies. A subsequent evaluation of 12 state-of-the-art security tools against this benchmark reveals an average detection rate of only 14.4%, highlighting that existing tools are ineffective at identifying these critical logic flaws. The third study addresses the limitations of existing approaches in identifying high-level semantic vulnerabilities, specifically Price Manipulation. As indicated by the second study, traditional tools struggle with logic flaws because they often lack the ability to interpret complex economic context. To bridge this gap, this study proposes PMDETECTOR, a hybrid framework designed to proactively detect price manipulation. The framework employs a three-stage pipeline to model economic semantics: (1) static taint analysis to identify potentially vulnerable paths, (2) a two-stage Large Language Model (LLM) analysis to filter effective defenses and simulate exploitation, and (3) a final static checker to validate findings. Evaluated on 73 vulnerable and 288 benign contracts, PMDETECTOR achieves up to 100% precision and 88% recall, with GPT-4o achieving a state-of-the-art F1-score of 0.91. Furthermore, in a large-scale scan of over 8,000 recently deployed contracts, it identified 4 previously unknown vulnerabilities, confirming its practical utility in securing the DeFi ecosystem. In summary, this thesis advances the field of smart contract security by bridging the gap be-tween empirical study and automated tool development. By characterizing defensive practices and investigating the limitations of existing security tools, this work paves the way for more effective detection methods. The proposed hybrid framework demonstrates that integrating static analysis with the semantic reasoning of LLMs can effectively identify complex semantic smart contract vulnerabilities, providing the community with insights and tools to safeguard decentralized applications.
Rapid urbanization in Tanzania has increased municipal solid waste generation and placed growing pressure on urban waste-management systems that remain focused mainly on collection, transport, and disposal. Given the high organic fraction of municipal waste generation. This paper examines Resource recovery from municipal waste through cost-effective biogas technologies in Tanzania, focusing on policy and institutional frameworks that support or constrain decentralized municipal organic waste-to-biogas systems that use appropriate standard procedures. The findings show that Tanzania has a broad policy framework for environmental protection, renewable energy, private-sector participation, and resource recovery, but this foundation has not been well translated into practice. Key constraints include fragmented mandates, limited biogas-specific standards, weak organic waste segregation, inadequate financing mechanisms, and insufficient formal inclusion of communities and informal waste actors. The paper argues that improving decentralized biogas implementation requires converting existing policy commitments into enforceable, financed, and locally coordinated municipal resource-recovery systems
Decentralized finance (DeFi) agents automate multi-transaction workflows such as swapping, lending, and vault management, but they also create process-level risk. A run can consist of individually valid calls while still becoming economically unsafe because an intermediate step leaves latent authority, weakens execution constraints, or accepts unverified external evidence. Existing defenses are often mismatched to this process-level risk. Off-chain preflight checks alone cannot protect against runtime deviations from the intended plan, and coarse on-chain allowlists are too weak to express the call-level intent that matters in DeFi. We present CheckpointAgent, a workflow-security architecture for checkpointed DeFi-agent execution. It composes manifest commitments, smart-account policy guards, post-state predicates, and attestation-gated advancement to constrain a run step by step and tie checkpoint advancement to verifiable evidence. Rather than judging safety only after a workflow finishes, CheckpointAgent checks whether each step remains consistent with the intended workflow and stops execution when the required conditions no longer hold. In the author-curated 27-scenario local-chain suite, the strongest evaluated setting preserves all 5 benign runs and prevents unsafe completion in all 22 adversarial runs, stopping them either through on-chain enforcement or through trusted-attestation advancement under the configured attester assumption. Under explicit trust assumptions and within the measured workflows and snapshots, checkpointed execution can materially reduce process-level risk without modifying target protocols.
Abhay Kumar R J, Dr. Bhavya Vikas, Dr. Sharath Ambrosse
The financial sector has been revolutionized by blockchain technology and digital assets, offering novel investment opportunities. Stable coins, in particular, have risen to the fore for their blend of blockchain benefits and moderate price fluctuations. Stable coins differ from other cryptocurrencies like Bitcoin (BTC) and Ethereum (ETH), which are known for their volatile price swings, with their stable value, meaning they can be employed in payment, trading, decentralized finance (De Fi), and portfolio management. This study aims to assess USDT and DAI's contribution to investment strategies in the current investment landscape between 2022 and 2026 alongside Bitcoin and Ethereum. The secondary data was analysed via time series analysis, 3 year moving average, rolling volatility, market capitalization, and correlation analysis of data obtained from Coin Market Cap, Coin Gecko, Reserve Bank publications and other financial databases. The results show that USDT and DAI possessed less volatility, more price stability and better capital preservation when compared to traditional cryptocurrencies. The study also finds that inflation, interest rates and US Dollar Index (DXY) affect the performance of stable coins and market demand. While there are regulatory, transparency, and market trust issues to address, stable coins have proven to be a potentially low-risk digital asset. In conclusion, according to the study, USDT and DAI are good investment alternatives for those who are looking for stability in the cryptocurrency market and are either conservative or new investors.
The rapid growth of the metaverse which is a virtual space that integrates augmentedreality, virtual reality, and blockchain technologies brought immense economicopportunities and challenges across the world. While developed nations increasinglyposition to leverage these opportunities, developing countries like Nigeria may faceunique obstacles in utilising the metaverse technology. It is in this regard, that thisstudy examines the legal and regulatory issues as it concerns the economic challengesposed by the metaverse in Nigeria's economy, indicating how regulatory gaps,infrastructure limitations, and inadequate legal frameworks can serve to impacteconomic participation in the growth of virtual spaces. Concerning this, the study willemploy the use of doctrinal methods of study, relying on primary and secondarysources of research materials. The data obtained from these sources were analysedusing a descriptive and analytical method of study. The study found that the conceptof metaverse has gained global recognition, and it could aid in the development of theNigerian economy. The study further found that several legal and social issues mayarise in utilising the metaverse concept in the Nigerian economy. Given the review ofcurrent legislation on virtual assets, decentralized finance, and immersive digitalinteractions, these challenges include data privacy, digital property rights, taxation,consumer protection, and cybersecurity. Hence, the study, therefore, concludes andrecommends that there is a need for Nigeria to implement a decent regulatoryapproach, considering both rights and interests when operating its economy throughmetaverse technology and economically maximizing the opportunities the metaversetechnology presents to Nigeria.