A Verifiable Deletion Protocol for Enhancing Constraints on Public Clouds

Public cloud environments enable multiparty collaboration and data sharing but are also prone to significant security challenges, particularly regarding verifiable data deletion. Existing tightly coupled protocols fall short in ensuring that deletion behaviors are executed honestly, leaving users unable to verify if their data has been truly erased. In this article, we address this critical issue by proposing a novel protocol paradigm to verify deletion behavior in public clouds. Our approach introduces the concepts of uncertainty requests and uncertainty roles, which obfuscate the cloud’s attack perspective by decoupling the relationship between deletion requests and credential responses. This decoupling prevents the cloud from identifying the requester’s identity or linking credentials to specific deletion requests, thereby imposing strict constraints on deletion behavior and enhancing resistance to unauthorized data retention. We formally define the security properties of our paradigm and provide a concrete instantiation of the protocol. Our security proofs demonstrate that the proposed protocol not only verifies deletion behavior but also resists backup attacks, targeting users, data blocks, and deletion requests. For performance, our experiments demonstrate from both computational efficiency and effectiveness evaluation. The results reveal lower computational overhead and superior security, making it highly suitable for practical deployment in public cloud environments.