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A lightweight auditing service for shared data with secure user revocation in cloud storage
, Article IEEE Transactions on Services Computing ; Volume 15, Issue 1 , 2022 , Pages 1-15 ; 19391374 (ISSN) ; Attari, M. A ; Asaar, M. R ; Aref, M. R ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2022
Abstract
As data sharing has become one of the most popular services offered by cloud storage, designing public auditing mechanisms for integrity of shared data becomes more important. Two problems which arise in shared data auditing include preserving users identity and collusion resistant revocation of users. When data stored at the cloud is shared among a group of users, different users may modify and sign different data blocks which leaks signer identities to the public verifier. Also, when a user is revoked from the group, signatures generated by this user should be re-signed by the cloud server using re-signature keys. In addition, collusion of cloud server and the revoked user should leak no...
Design of signature sequences for overloaded CDMA and bounds on the sum capacity with arbitrary symbol alphabets
, Article IEEE Transactions on Information Theory ; Volume 58, Issue 3 , 2012 , Pages 1441-1469 ; 00189448 (ISSN) ; Dashmiz, S ; Pad, P ; Marvasti, F ; Sharif University of Technology
2012
Abstract
In this paper, we explore some of the fundamentals of synchronous Code Division Multiple Access (CDMA) as applied to wireless and optical communication systems under very general settings (of any size) for the user symbols and the signature matrix entries. The channel is modeled by real/complex additive noise of arbitrary distribution. Two problems are addressed. The first problem concerns whether uniquely detectable overloaded matrices exist in the absence of additive noise under these general settings, and if so, whether there are any practical optimum detection algorithms. The second one is about the bounds for the sum channel capacity when user data and signature matrices employ any real...
Effect of data traffic shaping on throughput and delay for VSG-CDMA cellular networks
, Article 2007 IEEE International Conference on Telecommunications and Malaysia International Conference on Communications, ICT-MICC 2007, Penang, 14 May 2007 through 17 May 2007 ; February , 2007 , Pages 6-11 ; 1424410940 (ISBN); 9781424410941 (ISBN) ; Ashtiani, F ; Sharif University of Technology
2007
Abstract
In this paper, we analyze the effect of applying leaky bucket as a well known traffic shaper on data users in a variable spreading gain CDMA (VSG-CDMA) uplink wireless cellular network. To this end, we model the effect of leaky bucket mechanism on a typical data user, with a closed product form queueing network. Each node in this queueing network corresponds to a specific processing gain or equivalently transmission rate and power. By solving such a queueing network we obtain the steady state probability with which a typical data user will exist at each node. By aggregating the effects of all data users we compute the mean and variance of interference and obtain the throughput and average...