A Secure Erasure Code-Based Cloud Storage System with Secure Data Forwarding

Cloud storage is a service model in which data in maintained, managed and backed up remotely and made available to user over a network. Having your data stored offsite in the cloud makes it accessible from anywhere without the hassle of maintaining your own local storage and file-serving systems. It makes all the difference in a disaster, too. This cloud storage system, having collection of storage servers these are providing long term storage service over the internet. Storing the data into third party’s cloud system causes concern over data confidentiality. In this cloud some general encryption schemes protect data confidentiality, but also limit the functionality of the storage system because a few operations are supported over encrypted data. The main objective of this project is constructing a secure storage system that supports multiple functions is challenging when the storage system is distributed and has no central authority. In this project we propose a threshold proxy re-encryption scheme and integrate it which a decentralized erasure code such that a secure distributed storage system is formulated. The distributed storage system not only supports secure and robust data storage and retrieval, but also lets a user forward his data in the storage servers to another user without retrieving the data back. The main technical contribution is that the proxy re-encryption scheme supports encoding operations over encrypted messages as well as forwarding operations over encoded and encrypted messages. Our method fully integrates encrypting, encoding, and forwarding. We analyze and suggest suitable parameters for the number of copies of a message dispatched to storage servers and the number of storage servers queried by a key server. These parameters allow more flexible adjustment between the number of storage servers and robustness. Erasure encoding supports the forwarding scheme and applicable in decentralized distributed system. A decentralized erasure code is used to ensure the data robustness in the distributed cloud storage system. In erasure codes, the copy of the message is stored in the each storage servers. If one of the storage servers is failed, the message can be retrieved by one of the surviving server.