## 6 Conclusions  
This study presented a practical security assessment of Ethereum-based web applications, with a particular focus on the integration of cryptocurrency wallets and smart contracts. By developing and analyzing the BlockScribe prototype, we showed how wallet-contract integration patterns can expose applications to risks such as unauthorized access, weak input validation, improper fallback logic, and misconfigured access control. Although the methodology is tailored for Ethereum-compatible platforms (due to its reliance on Solidity and EVM tools), its principles--such as layered validation, symbolic analysis, and scenario-based testing--could be adapted to other ecosystems like Hyperledger Fabric, provided similar abstractions and tooling exist. Using static analysis tools (Mythril, Slither), targeted unit tests, and manual code inspection, we identified key vulnerability patterns and evaluated how modern Solidity features (e.g., version 0.8.28) mitigate common weaknesses. These include protections against arithmetic overflows, improved exception handling, and enhanced type safety. The analysis also highlighted broader integration challenges, such as the misuse of wallet APIs and the need for layered validation when accepting user input. Our findings emphasize that many security flaws originate not in the blockchain protocol itself but in the surrounding application logic and assumptions made at the interface layer. Although this research does not introduce novel cryptographic mechanisms or formal proofs, it contributes to a reproducible and tool-supported methodology to identify security flaws in real-world Ethereum applications. The simplified prototype and the step-by-step evaluation framework provide an accessible reference model for developers, security reviewers, and engineering teams looking to implement wallet-enabled smart contract logic in a secure and maintainable way. Future work may explore expanding the prototype to support Layer 2 integrations, decentralized identity authentication, and automated vulnerability certification frameworks such as the EEA EthTrust Security Levels. We also identify opportunities for integrating contract monitoring tools and runtime protection mechanisms that can provide early detection of wallet-side anomalies in production environments. In addition, while the current evaluation focuses on a single dApp-wallet pairing (BlockScribe with MetaMask), the proposed framework is not limited to this combination. The broad applicability to other Ethereum-based applications, such as decentralized exchanges, NFT platforms, or stake protocols, remains an open avenue for further exploration. Testing the methodology against alternative wallet interfaces (e.g., Rabby [51], OKX Wallet [52]) and under more diverse interaction patterns would help validate the generality and robustness of the framework across the ecosystem. Furthermore, while the current implementation performs well for moderate-sized contracts (less than 1000 lines of code), we recognize that symbolic execution and static analysis tools may face runtime and path-explosion challenges for larger contracts or complex Layer 2 setups. Future work may therefore include performance benchmarking, such as comparative gas profile, execution time tracking, and resource cost evaluation before and after vulnerability mitigation. Conceptualization, A.W. and G.J. ; methodology, A.W. ; software, G.J. ; validation, A.W. ; formal analysis, A.W. ; investigation, A.W. ; resources, A.W. and G.J. ; data curation, A.W. and G.J. ; writing--original draft preparation, A.W. ; writing--review and editing, A.W. ; visualization, G.J. ; supervision, A.W. ; project administration, A.W. ; funding acquisition, A.W. All authors have read and agreed to the published version of the manuscript. **Funding:** This study was funded by the Cracow University of Technology, Cracow, Poland. **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable.