Proofs of Retrievability (POR) are cryptographic proofs that enable a cloud provider to prove that a user can retrieve his file in its entirety. POR need to be frequently executed by the user to ensure that their files stored in the cloud can be fully retrieved at any point in time. To conduct and verify POR, users need to be equipped with devices that have network access, and that can tolerate the (non-negligible) computational overhead incurred by the verification process. This clearly hinders the large-scale adoption of POR by cloud users, since many users increasingly rely on portable devices that have limited computational capacity, or might not always have network access.

中文翻译：

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可检索性的外包证明

可检索性证明 (POR) 是加密证明，使云提供商能够证明用户可以完整地检索其文件。POR 需要用户频繁执行，以确保他们存储在云端的文件可以在任何时间点被完全检索。为了进行和验证 POR，用户需要配备具有网络访问权限的设备，并且可以容忍验证过程产生的（不可忽略的）计算开销。这显然阻碍了云用户大规模采用 POR，因为许多用户越来越依赖计算能力有限或可能无法始终访问网络的便携式设备。