多证明器可检索性证明
Multi-prover Proof-of-Retrievability
摘要：
最近对“云存储”有相当大的兴趣，其中用户要求服务器存储大文件。一个问题是用户是否可以验证服务器实际上正在存储文件，并且通常采用质询-响应协议来使用户相信文件确实被正确地存储。这些方案的安全性是用提取器来描述的，该提取器将在给定任何具有足够高的成功概率的“证明算法”的情况下恢复文件。这构成了\emph{proof-of-retrievability}（$\mathsf{PoR}$）系统的基础。本文研究了多服务器$\mathsf{PoR}$系统。我们形式化了两种可能情况下的安全定义：（i）当阈值的服务器成功的概率足够高（最坏情况）和（ii）当所有服务器的成功概率的平均值高于阈值（平均情况）。我们还鼓励研究外包信息的保密性。我们给$\mathsf{M}\mbox{-}\mathsf{PoR}$计划，这是安全的，在这两个安全的定义，并提供合理的保密性保证，即使没有限制的计算能力的服务器。我们还展示了Paterson，Stinson和Upadhyay（Journal of Mathematical Cryptology：7（3））使用的经典统计技术可以扩展到评估证明者的响应是否足够准确以允许成功提取。我们还研究了我们的构造的一个特定实例，当使用Shacham-Waters方案的无条件安全版本（Asiacrypt，2008）进行实例化时。该方案提供了合理的安全性和隐私性保证。我们表明，在多服务器设置与计算无界证明，可以克服的限制，验证者需要存储尽可能多的秘密信息的证明。
英文摘要：
There has been considerable recent interest in "cloud storage" wherein a user asks a server to store a large file. One issue is whether the user can verify that the server is actually storing the file, and typically a challenge-response protocol is employed to convince the user that the file is indeed being stored correctly. The security of these schemes is phrased in terms of an extractor which will recover the file given any "proving algorithm" that has a sufficiently high success probability. This forms the basis of \emph{proof-of-retrievability} ($\mathsf{PoR}$) systems. In this paper, we study multiple server $\mathsf{PoR}$ systems. We formalize security definitions for two possible scenarios: (i) when a threshold of servers succeed with high enough probability (worst-case) and (ii) when the average of the success probability of all the servers is above a threshold (average-case). We also motivate the study of confidentiality of the outsourced message. We give $\mathsf{M}\mbox{-}\mathsf{PoR}$ schemes which are secure under both these security definitions and provide reasonable confidentiality guarantees even when there is no restriction on the computational power of the servers. We also show how classical statistical techniques used by Paterson, Stinson and Upadhyay (Journal of Mathematical Cryptology: 7(3)) can be extended to evaluate whether the responses of the provers are accurate enough to permit successful extraction. We also look at one specific instantiation of our construction when instantiated with the unconditionally secure version of the Shacham-Waters scheme (Asiacrypt, 2008). This scheme gives reasonable security and privacy guarantee. We show that, in the multi-server setting with computationally unbounded provers, one can overcome the limitation that the verifier needs to store as much secret information as the provers.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
