A New Fog-Cloud Storage Framework with Transparency and Auditability

Recently, the concept of fog-cloud storage is attracting lots of attentions to overcome the limit of the central cloud storage. A storage audit scheme aims to ensure user that his/her data on the storage is sound. So far, various audit schemes have been introduced for cloud storages. However, compared to a central cloud storage, a distributed fog-cloud storage consists of multiple local fog storages in addition to a global cloud storage and therefore it is not straightforward to directly apply an existing audit scheme for a cloud storage to a fog-cloud storage. To address this issue, this paper introduces a new fog-cloud storage architecture which can achieve much higher throughput compared to the traditional central cloud storage architecture by reducing the traffics at the routers nearby the cloud storage. The proposed architecture provides transparency such that an end user device does not know the existence of fog storages, and only needs to upload its request toward the central cloud. This means that there is no need to make a modification on the existing end user devices. Our system provides a stronger audit scheme which is naturally coupled with the initial data upload process and does not suffer from the replay attack using old proof of data soundness.