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    Comments on a lightweight cloud auditing scheme: Security analysis and improvement

    , Article Journal of Network and Computer Applications ; Volume 139 , 2019 , Pages 49-56 ; 10848045 (ISSN) Rabaninejad, R ; Ahmadian Attari, M ; Rajabzadeh Asaar, M ; Aref, M. R ; Sharif University of Technology
    Academic Press  2019
    In a cloud storage service, public auditing mechanisms allow a third party to verify integrity of the outsourced data on behalf of data users without the need to retrieve data from the cloud server. Recently, Shen et al. proposed a new lightweight and privacy preserving cloud data auditing scheme which employs a third party medium to perform time-consuming operations on behalf of users. The authors have claimed that the scheme meets the security requirements of public auditing mechanisms. In this paper, we show that Shen et al.'s scheme is insecure by proposing two attacks on the scheme. In the first attack, an outside adversary can modify some messages in transmission to the cloud server... 

    Dynamics of scratch drive actuators during stepwise motion

    , Article Applied Mechanics and Materials ; Vol. 664, issue , 2014 , p. 104-110 Abtahi, M ; Vossoughi, G ; Meghdari, A ; Sharif University of Technology
    In this paper, a comprehensive model is used to describe dynamic behavior of SDA and its components during stepwise motion. In this model, Hamilton’s principle and Newton's method are used to extract dynamic equations of the SDA plate and dynamic equation for the linear motion of SDA. Comparison between the modeling results and available experimental data shows that this model is very effective in predicting some design objectives such as step size and output force for this type of actuators  

    Minimization of time to reach final speed in planing craft by optimal control of drive and trim tab angles

    , Article FAST 2013 - 12th International Conference on Fast Sea Transportation ; 2013 Yengejeh, M. A ; Seif, M. S ; Mehdigholi, H ; Sharif University of Technology
    FAST 2013 Secretariat  2013
    Properly adjusting the trim angle during the craft speed up, plays an important role in easily passing through the resistance hump and to reach final speed in minimum possible time. Present study tries to reply to this question that how the angles applied to a trimmable drive system and trim tab of the planing craft should be changed during speed up from rest, to craft reach a final speed in minimum time. This is a time-optimal control problem with the drive and trim tab angles as its control variables. To solve this problem a 3-DOF dynamic model is developed here rely on empirical data and relations. For the propulsion system operation of propeller, drive and engine altogether are taken... 

    NSSSD: A new semantic hierarchical storage for sensor data

    , Article 20th IEEE International Conference on Computer Supported Cooperative Work in Design, 4 May 2016 through 6 May 2016 ; 2016 , Pages 174-179 ; 9781509019151 (ISBN) Gheisari, M ; Movassagh, A. A ; Qin, Y ; Yong, J ; Tao, X ; Zhang, J ; Shen, H ; Liu, X. P ; Yong, J ; Barthes, J. P ; Shen, W ; Yang, C ; Luo, J ; Chen, L ; IEEE Systems, Man, and Cybernetics Society; International Working Group on Computer Supported Cooperative Work in Design (CSCWD) ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    Sensor networks usually generate mass of data, which if not structured for future applications, will require much effort on analytical processing and interpretations. Thus, storing sensor data in an effective and structured format is a key issue in the area of sensor networks. In the meantime, even a little improvement on data storing structure may lead to a significant effect on the lifetime and performance of the sensor network. This paper describes a new method for sensor storage that combines semantic web concepts, a data aggregation method along with aligning sensors in hierarchical form. This solution is able to reduce the amount of data stored at the sink nodes significantly. At the... 

    A verifiable delegated set intersection without pairing

    , Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 2047-2051 ; 9781509059638 (ISBN) Mahdavi Oliaiy, M ; Ameri, M. H ; Mohajeri, J ; Aref, M. R ; Sharif University of Technology
    Recently, there has been shown a great interest in the private set intersection (PSI) protocols which are widely used in social networks applications. In a PSI protocol two entities are able to find the intersection of their document set without inferring more information than the common data. In some PSI protocols the process of finding the intersections of the documents are delegated to a third entity like cloud which has high computational and storage resources and the clients can verify the accuracy of the received results. These protocols are known as the Verifiable Delegated Set Intersection (VDSI). In this paper, we proposed an efficient VDSI protocol by employing the El-Gamal... 

    Endurance-aware security enhancement in non-volatile memories using compression and selective encryption

    , Article IEEE Transactions on Computers ; Volume 66, Issue 7 , 2017 , Pages 1132-1144 ; 00189340 (ISSN) Jalili, M ; Sarbazi Azad, H ; Sharif University of Technology
    Emerging non-volatile memories (NVMs) are notable candidates for replacing traditional DRAMs. Although NVMs are scalable, dissipate lower power, and do not require refreshes, they face new challenges including shorter lifetime and security issues. Efforts toward securing the NVMs against probe attacks pose a serious downside in terms of lifetime. Cryptography algorithms increase the information density of data blocks and consequently handicap the existing lifetime enhancement solutions like Flip-N-Write. In this paper, based on the insight that compression can relax the constraints of lifetime-security trade-off, we propose CryptoComp, an architecture that, taking the advantage of block size... 

    Investigating power outage effects on reliability of solid-state drives

    , Article Proceedings of the 2018 Design, Automation and Test in Europe Conference and Exhibition ; Volume 2018-January , 2018 , Pages 207-212 ; 9783981926316 (ISBN) Ahmadian, S ; Taheri, F ; Lotfi, M ; Karimi, M ; Asadi, H ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Solid-State Drives (SSDs) are recently employed in enterprise servers and high-end storage systems in order to enhance performance of storage subsystem. Although employing high speed SSDs in the storage subsystems can significantly improve system performance, it comes with significant reliability threat for write operations upon power failures. In this paper, we present a comprehensive analysis investigating the impact of workload dependent parameters on the reliability of SSDs under power failure for variety of SSDs (from top manufacturers). To this end, we first develop a platform to perform two important features required for study: A) a realistic fault injection into the SSD in the... 

    Possibilistic Art (PoArt), an Approach based on Mind Geometry for Digital Media

    , Article 5th Iranian Conference on Signal Processing and Intelligent Systems, ICSPIS 2019, 18 December 2019 through 19 December 2019 ; 2019 ; 9781728153506 (ISBN) Asasian Kolur, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    This paper, in the domain of digital media, introduces the theoretical basis of possibilistic art. It models the bases of visual art in the atmosphere of possibilistic thought and the fuzzy geometry by introducing meaningful forms and introduces a way for recording and displaying emotional-behavioral responses of artist in the visualcomputational space. Finally, as a function of presented concepts, the paper introduces a semi-algorithm for meaningful deformation. This article, by representation of a method based on the eastern thinking and a computational thinking of the west, make a step in the way of eliminating the theoretic and instrumental shortages of visual arts of Iran in the grounds... 

    A lightweight identity-based provable data possession supporting users’ identity privacy and traceability

    , Article Journal of Information Security and Applications ; Volume 51 , 2020 Rabaninejad, R ; Ahmadian Attari, M ; Rajabzadeh Asaar, M ; Aref, M. R ; Sharif University of Technology
    Elsevier Ltd  2020
    Cloud storage auditing is considered as a significant service used to verify the integrity of data stored in public cloud. However, most existing auditing protocols suffer form complex certificate management/verification since they rely on expensive Public Key Infrastructure (PKI). On the other hand, most cloud users have constrained computational resources. The few existing ID-based storage auditing protocols in the literature, require resource-constrained users to perform costly operations for generating metadata on file blocks. In this paper, we propose a storage auditing protocol which benefits from ID-based structure and lightweight user computations, simultaneously. Our construction... 

    System modeling and optimization for islanded micro-grid using multi-cross learning-based chaotic differential evolution algorithm

    , Article International Journal of Electrical Power and Energy Systems ; Vol. 56 , 2014 , pp. 349-360 ; ISSN: 01420615 Hemmati, M ; Amjady, N ; Ehsan, M ; Sharif University of Technology
    This paper presents a comprehensive operation model for micro-grids (MG) operating in the islanded mode. Various energy sources of a MG including diesel engine generator, micro-turbine, wind turbine and photovoltaic cell as well as battery storage and AC/DC rectifier/inverter are modeled in the proposed framework. Fuel costs, emission costs, and operation and maintenance (O&M) costs of these sources as well as their operating limits and characteristics are considered in the model. Furthermore, a new multi-cross learning-based chaotic differential evolution (MLCDE) algorithm is presented to solve the optimization problem of MG operation. The numerical results obtained from the proposed... 

    Applying a robust solution based on expert systems and GA evolutionary algorithm for prognosticating residual gas saturation in water drive gas reservoirs

    , Article Journal of Natural Gas Science and Engineering ; Vol. 21, issue , November , 2014 , p. 79-94 Tatar, A ; Yassin, M. R ; Rezaee, M ; Aghajafari, A. H ; Shokrollahi, A ; Sharif University of Technology
    In strong water drive gas reservoirs (WDGRs), the water encroachment in the gas zone has adverse effects on the gas mobility and causes considerable volume of gas to be trapped behind water front; therefore estimation of residual gas saturation after water influx is an important parameter in estimation of gas reservoirs with strong aquifer support. It is difficult to achieve a thorough and exact understanding of water drive gas reservoirs. It depends on several parameters of petrophysical and operational features. In majority of the previous studies about residual gas saturation, the correlations were depended on petrophysical properties such as porosity, permeability, and initial gas... 

    A power-efficient reconfigurable architecture using PCM configuration technology

    , Article Proceedings -Design, Automation and Test in Europe, DATE ; 2014 Ahari, A ; Asadi, H ; Khaleghi, B ; Tahoori, M. B ; Sharif University of Technology
    Promising advantages offered by resistive NonVolatile Memories (NVMs) have brought great attention to replace existing volatile memory technologies. While NVMs were primarily studied to be used in the memory hierarchy, they can also provide benefits in Field-Programmable Gate Arrays (FPGAs). One major limitation of employing NVMs in FPGAs is significant power and area overheads imposed by the Peripheral Circuitry (PC) of NVM configuration bits. In this paper, we investigate the applicability of different NVM technologies for configuration bits of FPGAs and propose a power-efficient reconfigurable architecture based on Phase Change Memory (PCM). The proposed PCM-based architecture has been... 

    Exploring self-organized criticality conditions in Iran bulk power system with disturbance times series

    , Article Scientia Iranica ; Vol. 21, issue. 6 , 2014 , p. 2264-2272 ; 10263098 Karimi, E ; Ebrahimi, A ; Fotuhi-Firuzabad, M ; Sharif University of Technology
    Ubiquitous power-law as a fingerprint of Self-Organized Criticality (SOC) is used for describing catastrophic events in different fields. In this paper, by investigating the prerequisites of SOC, we show that SOC-like dynamics drive a correlation among disturbances in Iranian bulk power systems. The existence of power-law regions in probability distribution is discussed for empirical data using maximum likelihood estimation. To verify the results, long time correlation is evaluated in terms of Hurst exponents, by means of statistical analysis of time series, including Rescaled Range (R/S) and Scaled Windowed Variance (SWV) analysis. Also, sensitivity analysis showed that for correct... 

    LSB ++: An improvement to LSB + steganography

    , Article IEEE Region 10 Annual International Conference, Proceedings/TENCON, 21 November 2011 through 24 November 2011, Bali ; 2011 , Pages 364-368 ; 9781457702556 (ISBN) Ghazanfari, K ; Ghaemmaghami, S ; Khosravi, S. R ; Sharif University of Technology
    The Least Significant Bit (LSB) substitution is an old and simple data hiding method that could almost effortlessly be implemented in spatial or transform domain over any digital media. This method can be attacked by several steganalysis methods, because it detectably changes statistical and perceptual characteristics of the cover signal. A typical method for steganalysis of the LSB substitution is the histogram attack that attempts to diagnose anomalies in the cover image's histogram. A well-known method to stand the histogram attack is the LSB + steganography that intentionally embeds some extra bits to make the histogram look natural. However, the LSB + method still affects the perceptual... 

    An intelligent modeling approach for prediction of thermal conductivity of CO2

    , Article Journal of Natural Gas Science and Engineering ; Volume 27 , November , 2015 , Pages 138-150 ; 18755100 (ISSN) Shams, R ; Esmaili, S ; Rashid, S ; Suleymani, M ; Sharif University of Technology
    Elsevier  2015
    In the design of a carbon dioxide capture and storage (CCS) process, the thermal conductivity of carbon dioxide is of special concern. Hence, it is quite important to search for a quick and accurate determination of thermal conductivity of CO2 for precise modeling and evaluation of such a process. To achieve this aim, a robust computing methodology, entitled least square support vector machine (LSSVM) modeling, which is coupled with an optimization approach, was used to model this transport property. The model was constructed and evaluated employing a comprehensive data bank (more than 550 data series) covering wide ranges of pressures and temperatures. Before constructing the model, outlier... 

    Dynamic modeling of scratch drive actuators

    , Article Journal of Microelectromechanical Systems ; Volume 24, Issue 5 , April , 2015 , Pages 1370-1383 ; 10577157 (ISSN) Abtahi, M ; Vossoughi, G ; Meghdari, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    There has been much research in developing scratch drive actuators (SDAs), but because of their dynamic complexity, these microelectromechanical system-based actuators have not been dynamically analyzed up to now. In this paper, a comprehensive model is presented to describe the dynamic behavior of SDA and its components during stepwise motion. In this model, Hamilton's principle and Newton's method are used to extract dynamic equations of the SDA plate and dynamic equation for the linear motion of SDA. This model presents a good insight into the operating principles of SDA by predicting the variation of different variables, such as bushing angle, contact length, horizontal position, and... 

    DiskAccel: Accelerating disk-based experiments by representative sampling

    , Article Performance Evaluation Review, 15 June 2015 through 19 June 2015 ; Volume 43, Issue 1 , 2015 , Pages 297-308 ; 01635999 (ISSN) Tarihi, M ; Asadi, H ; Sarbazi Azad, H ; Sharif University of Technology
    Association for Computing Machinery  2015
    Disk traces are typically used to analyze real-life workloads and for replay-based evaluations. This approach benefits from capturing important details such as varying behavior patterns, bursty activity, and diurnal patterns of system activity, which are often missing from the behavior of workload synthesis tools. However, accurate capture of such details requires recording traces containing long durations of system activity, which are difficult to use for replay-based evaluation. One way of solving the problem of long storage trace duration is the use of disk simulators. While publicly available disk simulators can greatly accelerate experiments, they have not kept up with technological... 

    Operating system level data tiering using online workload characterization

    , Article Journal of Supercomputing ; Volume 71, Issue 4 , April , 2015 , Pages 1534-1562 ; 09208542 (ISSN) Salkhordeh, R ; Asadi, H ; Ebrahimi, S ; Sharif University of Technology
    Kluwer Academic Publishers  2015
    Over the past decade, storage has been the performance bottleneck in I/O-intensive programs such as online transaction processing applications. To alleviate this bottleneck with minimal cost penalty, cost-effective design of a high-performance disk subsystem is of decisive importance in enterprise applications. Data tiering is an efficient way to optimize cost, performance, and reliability in storage servers. With the promising advantages of solid-state drives (SSDs) over hard disk drives (HDDs) such as lower power consumption and higher performance, traditional data tiering techniques should be revisited to use SSDs in a more efficient way. Previously proposed tiering solutions have... 

    Security and searchability in secret sharing-based data outsourcing

    , Article International Journal of Information Security ; Volume 14, Issue 6 , November , 2015 , Pages 513-529 ; 16155262 (ISSN) Hadavi, M. A ; Jalili, R ; Damiani, E ; Cimato, S ; Sharif University of Technology
    Springer Verlag  2015
    A major challenge organizations face when hosting or moving their data to the Cloud is how to support complex queries over outsourced data while preserving their confidentiality. In principle, encryption-based systems can support querying encrypted data, but their high complexity has severely limited their practical use. In this paper, we propose an efficient yet secure secret sharing-based approach for outsourcing relational data to honest-but-curious data servers. The problem with using secret sharing in a data outsourcing scenario is how to efficiently search within randomly generated shares. We present multiple partitioning methods that enable clients to efficiently search among shared... 

    A hybrid DCT-SVD based image watermarking algorithm

    , Article 24th Iranian Conference on Electrical Engineering, ICEE 2016, 10 May 2016 through 12 May 2016 ; 2016 , Pages 838-843 ; 9781467387897 (ISBN) Heidari, M ; Karimi, N ; Samavi, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Everyday, people share their digital media on the virtual networks; therefore, protecting them against piracy is worthy of consideration. Digital watermarking is a method to achieve this goal. In this paper, we propose a watermarking method in Discrete Cosine Transform (DCT) domain. For this purpose, DCT coefficients of the whole image are calculated. It helps to present a system without blockiness effects. Then, singular values of the watermark image are added to the low frequency DCT coefficients of cover image that are located on the main diagonal. We use scaling factors for watermark embedding to improve imperceptibility of the watermark. A vector of fixed elements, which is calculated...