Collaborative and Searchable Integrity Auditing for Multi-Copy Data in Decentralized Storage

As decentralized storage becomes more prevalent, ensuring data integrity within these systems has gained increasing importance. However, the introduction of a centralized and trusted Cloud Combiner (CO) to manage auditing across distributed Cloud Servers (CSs) presents several challenges, which not only increases communication costs with independent CSs but also diminishes the credibility of the auditing results. Additionally, traditional approaches often require either certificate and key management or the establishment of secure transmission channels, which incur substantial overhead. Furthermore, the computational cost for index generation to support searchable auditing is often high. To address these challenges, we propose a collaborative and searchable integrity auditing scheme for multi-replica data that eliminates the need for a CO. Specifically, we design a certificate-based authenticator for multi-copy data blocks, which simplifies certificate and key management while removing the need for secure channels. To enable efficient searchable auditing, we introduce a novel index tag that matches authenticators, thereby reducing the computational overhead. Moreover, we leverage blockchain technology to enhance the credibility of the auditing process and ensure the integrity of the search results. Both security and performance analyses demonstrate that the proposed scheme is secure and efficient.