Cloud service providers offer various facilities to their clients. The clients with limited resources opt for some of these facilities. They can outsource their bulk data to the cloud server. The cloud server maintains these data in lieu of monetary benefits. However, a malicious cloud server might delete some of these data to save some space and offer this extra amount of storage to another client. Therefore, the client might not retrieve her file (or some portions of it) as often as needed. Proofs of retrievability (POR) provide an assurance to the client that the server is actually storing all of her data appropriately and they can be retrieved at any point of time. In a dynamic POR scheme, the client can update her data after she uploads them to the cloud server. Moreover, in publicly verifiable POR schemes, the client can delegate her auditing task to some third party specialized for this purpose. In this work, we exploit the homomorphic hashing technique to design a publicly verifiable dynamic POR scheme that is more efficient (in terms of bandwidth required between the client and the server) than the “state-of-the-art” publicly verifiable dynamic POR scheme. We also analyze security and performance of our scheme.

中文翻译：

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具有公共可验证性的动态云存储可检索性的有效证明

云服务提供商为其客户提供各种设施。资源有限的客户选择其中一些设施。他们可以将批量数据外包给云服务器。云服务器维护这些数据而不是金钱利益。但是，恶意云服务器可能会删除其中一些数据以节省一些空间并将这些额外的存储量提供给另一个客户端。因此，客户端可能不会根据需要经常检索她的文件（或其中的某些部分）。可检索性证明 (POR) 向客户端保证服务器实际上正确存储了她的所有数据，并且可以在任何时间点检索这些数据。在动态 POR 方案中，客户端可以在将数据上传到云服务器后更新她的数据。此外，在可公开验证的 POR 方案中，客户可以将她的审计任务委托给专门为此目的的第三方。在这项工作中，我们利用同态散列技术设计了一个公开可验证的动态 POR 方案，该方案比“最先进的”公开可验证动态 POR 方案更有效（就客户端和服务器之间所需的带宽而言）方案。我们还分析了我们方案的安全性和性能。