Briefing
Cloud storage faces challenges in ensuring data security, reducing costs from redundant data, protecting user ownership privacy during deduplication and auditing, and eliminating reliance on untrustworthy third-party auditors. This paper introduces a blockchain-based scheme that integrates Identity-Based Broadcast Encryption (IBBE) for efficient key management and smart contracts for decentralized integrity auditing, with a core innovation involving randomizing file tags and audit proofs to fundamentally protect user file ownership privacy during both deduplication and auditing processes. This theoretical advance establishes a model for self-sovereign data management in decentralized cloud environments, significantly enhancing data security and user privacy while reducing operational overhead.
Context
Before this research, Provable Data Possession (PDP) schemes enabled remote data integrity verification, and Message-Locked Encryption (MLE) facilitated secure data deduplication in cloud storage. These approaches often suffered from critical limitations, including the exposure of user file ownership privacy during deduplication and auditing, the inherent security risks and high costs associated with relying on fully trusted third-party auditors (TPAs), and the escalating burden of key management for users as data volumes increased. The prevailing theoretical challenge centered on achieving both efficiency and comprehensive privacy in decentralized cloud storage without compromising data integrity or introducing new centralized trust assumptions.
Analysis
The scheme’s core mechanism revolves around three integrated components ∞ blockchain for decentralized trust, Identity-Based Broadcast Encryption (IBBE) for streamlined key management, and randomized cryptographic elements for privacy. When a user uploads a file, it is encrypted using a randomly selected key. The system then generates unique, randomized file tags and authentication tags for deduplication, ensuring that even if identical files exist, their public tags do not reveal common ownership. Smart contracts on the blockchain initiate and verify data integrity challenges, publishing results transparently without exposing audit proofs or user identities, a function previously handled by central auditors.
IBBE allows multiple authorized users to decrypt a shared file using their individual identity-based keys, eliminating the need for a central key server and simplifying key management. This fundamentally differs from prior methods by decentralizing auditing and key management while proactively safeguarding ownership privacy through cryptographic randomization.
Parameters
Outlook
This research paves the way for advanced decentralized cloud storage solutions, where data integrity and user privacy are intrinsically guaranteed by cryptographic primitives and blockchain mechanisms. The next steps in this area will likely involve optimizing the computational overheads of audit proof generation, exploring integration with other privacy-enhancing technologies like secure multi-party computation for more complex data operations, and extending the framework to support dynamic data updates with similar privacy guarantees. In the next 3-5 years, this theory could unlock real-world applications such as fully private and auditable decentralized file storage networks, secure data marketplaces where ownership is protected, and highly efficient enterprise cloud solutions that leverage deduplication without sacrificing confidentiality.