GAS4SEC: Toward a Secure and Optimized Smart Contract for Digital Chain of Custody in Digital Forensics

Abstract

It is evident that blockchain offers strong guarantees of integrity and transparency for handling digital evidence; however, its practical adoption has remained a challenge due to factors such as privacy, deployment constraints, and admissibility issues in the real word environment. This study, therefore, proposes GAS4SEC, a framework for designing, validating, and deploying a secure, cost effective, and forensically sound blockchain-based evidence management system. The system combines formally bound smart contract architecture with role-based access control, record of immutable evidences and custody processes to maintain authenticity, traceability and accountability. In order to overcome the security risks and challenges, the research includes the systematic vulnerability analysis correlated with the OWASP smart contract risks to make sure that unauthorized access, logic abuse, and invalid state transitions are addressed. A validation-based process of development imposes forensic invariants and security guarantees across the lifetime of a contract, and controlled gas optimization is used to achieve better deployment without affecting the evidentiary integrity. The proposed system is deployed and tested on the Polygon Layer-2 blockchain, with functional testing, security testing, gas testing, and stress testing with evidence operations and role change concurrency. The experiment proves that the approach can be used to achieve scalable and cost-effective on-chain forensics operations without sacrificing the high levels of security assistance and forensic integrity and proves to be applicable to the management of digital evidence in practice.