Proof of Storage (PoS) enables a cloud storage provider to prove that a client’s data is intact. However, existing PoS protocols are not designed for the pay-as-you-go business model in which payment is made based on both storage volume and duration. In this paper, we propose two PoS protocols suitable for the pay-as-you-go storage business model. The first is a time encapsulated Proof of Retrievability (PoR) protocol that ensures retrievability of the original file upon successful auditing by a client. Considering the large size of outsourced data, we then extend the protocol to a privacy-preserving public auditing protocol which allows a third party auditor to audit outsourced data on behalf of its clients without sacrificing the privacy of the data or the timestamp (i.e., time of storage). We formalize the definition, system model and security model of the proposed PoS system and prove the security of the proposed protocols by a sequence of games in the algebraic group model with a random oracle. We analyze the performance of the protocols both theoretically and experimentally and show that the protocols are practical.

中文翻译：

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即用即付业务模型的隐私保护存储证明

存储证明（PoS）使云存储提供商可以证明客户端的数据是完整的。但是，现有的PoS协议不适用于即用即付的业务模型，在该模型中，将根据存储量和持续时间进行付款。在本文中，我们提出了两种适合随用随付存储业务模型的PoS协议。第一个是时间封装的可检索性证明（PoR）协议，可确保在客户端成功审核后可检索原始文件。考虑到外包数据的规模大，我们然后将该协议扩展到了一个保护隐私的公共审核协议，该协议允许第三方审核员代表其客户审核外包数据，而不会牺牲数据的隐私性或时间戳（即时间）的存储空间）。我们将定义形式化，PoS系统的系统模型和安全模型，并通过带有随机预言的代数组模型中的一系列游戏证明了所提出协议的安全性。我们从理论上和实验上分析了协议的性能，并证明了该协议是实用的。