Enhanced Transactional Blockchain Data Access Control via Fog Computing and Multilevel Aggregation Encryption

Despite the praise for blockchain technology's auditability, security, and decentralization, safeguarding Personally Identifiable Information (PII) continues to pose a challenge, especially in the field of financial transactions. Existing schemes often fail to effectively balance security with efficiency, fine-grained access control, and distributed processing. Many approaches either sacrifice performance for enhanced security or struggle with the complexity of managing fine-grained access in a decentralized manner. To address these shortcomings, a novel schema is proposed that integrates Ciphertext-Policy Attribute-Based Encryption (CP-ABE) with a lightweight fog layer to offload heavy cryptographic operations. This solution reduces policy tree complexity and mitigates side-channel attacks through a multi-layer encryption model. The approach enhances data confidentiality with minimal impact on transaction performance, offering a more secure, efficient, and distributed solution. This research validates the design with mathematical proof and performance comparisons against existing implementations.