Creating A New Storage Scheme

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Hourglass Schemes: [1] As mentioned in the introduction, ensuring files confidentiality is a major issue in cloud computing. The authors of this paper introduce a new storage scheme called the HourGlass. In this scheme the cloud server is forced to save files in a way that enable clients challenges, the server’s response ensures clients that their files are safely stored. In most cloud providers, clients files are stored in an encrypted way based on some predefined agreement between the client and the cloud provider. Then clients can challenge the server to send back the encrypted files in timely manners. The problem with this scenario is with current resources and computation powers, the servers can easily encrypt files on the fly and…show more content…
This is most likely to exceed the time limit and hence the client will know that the server is not storing their files is a secure manner. The second property is also important because this scheme should not introduce any complication to the clients when trying to access their file. When legitimate clients want to access their files on the server, they should also be easily able to uncover the hourglass encapsulation, decrypt their file and read the plain text. We will describe the proposed protocol using the following notations: F: the plaintext file, CipherF: the encrypted file, X: The output of the hourglass function that will be stored on the server, C: the client, S: the server, HG: the hourglass function, E: encryption function, RNG(): random number generator that will be used by the client , A >> B: M: A sending M to B. The protocol is as follows: Client Server F C >> S: F F CipherF = E(F) X = HG(CipherF) Discard F, Store X i = GEN(), start timer C >> S: i i Stop timer C << S: block i of X Verify response Remark: this is a simplified version of the actual protocol; more details will be introduced in the final report. The client can verify the server response either by computing HG and storing it on the client side or by other means that will be explained in the final report. The
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