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privacy-preserving
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(t,k)-Hypergraph anonymization: An approach for secure data publishing
, Article Security and Communication Networks ; Volume 8, Issue 7 , September , 2015 , Pages 1306-1317 ; 19390114 (ISSN) ; Hadavi, M. A ; Jalili, R ; Sharif University of Technology
John Wiley and Sons Inc
2015
Abstract
Privacy preservation is an important issue in data publishing. Existing approaches on privacy-preserving data publishing rely on tabular anonymization techniques such as k-anonymity, which do not provide appropriate results for aggregate queries. The solutions based on graph anonymization have also been proposed for relational data to hide only bipartite relations. In this paper, we propose an approach for anonymizing multirelation constraints (ternary or more) with (t,k) hypergraph anonymization in data publishing. To this end, we model constraints as undirected hypergraphs and formally cluster attribute relations as hyperedge with the t-means-clustering algorithm. In addition,...
Minimal assumptions to achieve privacy in e-voting protocols
, Article 2013 10th International ISC Conference on Information Security and Cryptology, ISCISC 2013 ; 29- 30 August , 2013 ; Kargar, M. A ; Dousti, M. S ; Jalili, R ; Sharif University of Technology
IEEE Computer Society
2013
Abstract
Chevallier-Mames et al, proved that in a specific condition (such as the lack of untappable channels and trusted-third parties), the universal verifiability and privacy-preserving properties of e-voting protocols are incompatible (WOTE'06 and TTE'10). In this paper, we first show a flaw in their proof. Then, we prove that even with more assumptions, such as the existence of TTPs and untappable channels between the authorities, an e-voting protocol is unable to preserve privacy, regardless of verifiability. Finally, we demonstrate that preserving privacy in e-voting protocols requires the provision of at least one of the following assumptions: limited computational power of adversary,...
A secure ECC-based privacy preserving data aggregation scheme for smart grids
, Article Computer Networks ; Volume 129 , 2017 , Pages 28-36 ; 13891286 (ISSN) ; Bayat, M ; Pakravan, M. R ; Aref, M. R ; Sharif University of Technology
Abstract
Development of Smart Grid and deployment of smart meters in large scale has raised a lot of concerns regarding customers’ privacy. Consequently, several schemes have been proposed to overcome the above mentioned issue. These schemes mainly rely on data aggregation as a method of protecting users’ privacy from the grid operators. However, the main problem with most of these schemes is the fact that they require a large amount of processing power at the meter side. This, together with the fact that smart meters don't usually have a powerful processor, can cause the unavailability of smart meter data at the required time for operators of the grid, and at the same time prevents smart meters from...
An identity-based online/offline secure cloud storage auditing scheme
, Article Cluster Computing ; Volume 23, Issue 2 , 2020 , Pages 1455-1468 ; Rajabzadeh Asaar, M ; Ahmadian Attari, M ; Aref, M. R ; Sharif University of Technology
Springer
2020
Abstract
Cloud storage has significantly reduced data management costs for data owners. However, loss of physical control over the data after outsourcing, triggers some security concerns such as data integrity. Provable Data Possession (PDP) protocols, enable data owners to audit the integrity of their outsourced data without the need to retrieve the file from cloud server. However, most existing PDP schemes require resource-constrained users to perform costly operations for generating metadata on file blocks. In online/offline PDP mechanisms introduced most recently, the user’s computation is divided into online/offline phases, where the costly operations are allowed to be carried out in the offline...
Design and Analysis of Authentication Protocols in Vehicular ad-hoc Networks
, M.Sc. Thesis Sharif University of Technology ; Salmasizadeh, Mahmoud (Supervisor) ; Mohajeri, Javad (Co-Supervisor)
Abstract
Design of anonymous authentication scheme is one of the most important challenges in Vehicular Ad hoc Networks (VANET). Most of the existing schemes have high computational and communication overhead and they do not meet security requirements. Recently, Azees et al. have introduced an Efficient Anonymous Authentication with Conditional Privacy-Preserving (EAAP) scheme for VANET and claimed that it is secure. We show that this protocol is vulnerable against replay attack, impersonation attack and message modification attack. Also, we show that the messages sent by a vehicle are linkable. Therefore, an adversary can easily track the vehicles. In addition, it is shown that vehicles face with...
Privacy Preserving Access Control in IoT for eHealth
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
One of the applications of Internet of things (IoT) is its usage in the eHealth area. Various types of sensors (e.g., sensor to measure heart health, blood sugar levels, and respiratory) exist that not only provide required information for patients, but also send the health information to hospital staff through the network. Leveraging this technology in various intensive care units of hospital facilitate nurses and medical staff in monitoring of patients. However, moving towards these environments leads to new security challenges. One of the most important challenges is controlling access to sensors’ data and preserving patients privacy so that doctor and nurses should access patients’...
Private Distributed Computing for Machine Learning Algorithms
, M.Sc. Thesis Sharif University of Technology ; Maddah-Ali, Mohammad Ali (Supervisor) ; Mirmohseni, Mahtab (Co-Supervisor)
Abstract
In this thesis, we argue that in many basic algorithms for machine learning, including support vector machine (SVM) for classification, principal component analysis (PCA) for dimensionality reduction, and regression for dependency estimation, we need the inner products of the data samples, rather than the data samples themselves. Motivated by the above observation, we introduce the problem of private inner product retrieval for distributed machine learning, where we have a system including a database of some files, duplicated across some non-colluding servers. A user intends to retrieve a subset of specific size of the inner products of the data files with minimum communication load, without...
Preserving Privacy in Smart Grid
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Pakravan, Mohammad Reza (Co-Advisor)
Abstract
Development of Smart Grid and deployment of smart meters in large scale has raised a lot of concerns regarding customers’ privacy. Consequently, several schemes have been proposed to overcome the above mentioned issue. These schemes mainly rely on data aggregation as a method of protecting users’ privacy from the grid operators. However, the main problem with most of these schemes is the fact that they require a large amount of processing power at the meter side. This, together with the fact that smart meters don’t usually have a powerful processor, can cause the unavailability of smart meter data at the required time for operators of the grid, and at the same time disables smart meters from...
Privacy Improvement Of Opportunistic Network Routing
, M.Sc. Thesis Sharif University of Technology ; Movaghar, Ali (Supervisor)
Abstract
Opportunistic delay tolerance networks are widely used networks that do not require infrastructure. Many routing algorithms have been proposed for these networks in which nodes need to compare their metrics (such as visit frequency, node geographical location, etc.)Therefore, routing in these networks has a high security risk and the possibility of violating privacy. There are many ways to protect privacy, but these methods have limitations: some are limited to vehicles and some are limited to social networks and node communities. Also, more general methods require a lot of complexity, including processing time, storage resources, and key management.In this study, we propose a method with...
Reuse-attack mitigation in wireless sensor networks
, Article IEEE International Conference on Communications, 5 June 2011 through 9 June 2011 ; June , 2011 , Page(s): 1 - 5 ; 05361486 (ISSN) ; 9781612842332 (ISBN) ; Khonsari, A ; Mirzasoleiman, B ; Ould Khaoua, M ; Sharif University of Technology
2011
Abstract
Privacy preservation in wireless sensor networks has drawn considerable attention from research community during last few years. Emergence of single-owner, multi-user commercial sensor networks along with hostile and uncontrollable environment of such networks, makes the security issue in such networks of a great importance. This paper concentrates on token-based privacy preservation schemes. A possible attack on such schemes has been introduced. Two different approaches has been utilized to mitigate the attack. We present mathematical models for it's effects and overheads. The results have been verified using extensive simulations
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) ; Ahmadian Attari, M ; Rajabzadeh Asaar, M ; Aref, M. R ; Sharif University of Technology
Academic Press
2019
Abstract
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...
Privacy Preserving Access Control for Service Composition in Cloud Computing
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
Cloud computing is a new computing environment where computing infrastructure, platform and software are provided as a service. Rapid growth of cloud environments has increased the importance of security requirements and challenges for both service providers and users in cloud. Two main security issues in software as a service (SaaS) delivery model are access control and privacy preserving in basic web services and also in composite services obtaining through the automatic composition and inference of policies from the ones specified for basic services. In this thesis, we present a privacy preserving access control model and framework for service composition in SaaS delivery model of cloud...
Information-flow Analysis in Android Apps for Protecting User Privacy
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
The rapid growth of Android operating system alongside its open-source nature has made it as the most popular operating system of mobile devices. On the other hand, regarding the increasing computational power of mobile devices, a wide variety of applications are coming to this type of devices. Meanwhile unfortunately many malicious softwares trying to keep up with other applications, are targeting this popular operating system. Therefore with regard to the fact that this type of devices usually store private and sensitive information of their users, security of mobile operating systems is considered very important. Having this matter in mind, the goal of this research work has been...
A New Cooperative Message Authentication Scheme in Vehicular ad-hoc Networks
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Salmasizadeh, Mahmoud (Co-Advisor)
Abstract
Real-time applications play a significant role in the area of VANET, and are mainly required for these kinds of networks. On the other hand, when the number of messages received by vehicles increases in the network, then the applied computation load becomes extremely high and consequently, delay on the message authentication process significantly increases. This thesis, is presented with the aim of introducing a novel cooperative message authentication (CMA) scheme for VANET, the main purpose of which is alleviating the computation load on vehicles while verifying messages by using two-part identity-based signature. The scheme enables vehicles to verify only a limited number of the total...
Improving the Security of Private Set Intersectio
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Mohajeri, Javad (Co-Advisor)
Abstract
In some applications in the field of information technology such as social networks and medical databases in different hospitals, sometimes an entity needs to calculate the extent of its sharing of information documents with other institutions. Access to one entity's information is not possible due to the confidentiality of users' information. Therefore, in order to calculate common documents, users should be able to do so without revealing their private information. Therefore, it is required protocols such that can only obtain the shared information between two mentioned entities, while preserving the confidentiality of uncommon information. The schemes that meet the above objectives are...
User Authentication in IoT and it’s Application in Smart Grid
, M.Sc. Thesis Sharif University of Technology ; Aref, Mohammad Reza (Supervisor) ; Salmasizadeh, Mahmoud (Co-Supervisor)
Abstract
The Internet of Things (IoT) is rapidly expanding as an emerging concept. The connection of billions of objects and human beings creates serious challenges. Security is one of the major challenges faced by the Internet of Things, and a standardized scheme to meet security requirements has not yet been introduced. Authentication and privacy preserving users is one of the important security requirements. In this thesis, a user and a message authentication scheme in the Internet of Things are introduced, which simultaneously preserving the conditional privacy of the users. The scheme that proposed on Identity Based signature, in the verification phase user signature is verified Simultaneous,...
Attacking Tor; A Report on RAPTOR and Similar Attacking Tors
, M.Sc. Thesis Sharif University of Technology ; Peyvandi, Hossein (Supervisor)
Abstract
Coming to the generation of technology, where everything is possible through the Internet contributes a significant proportion to privacy protection. Several Privacy protection technologies have been launched to maintain the confidentiality of user information. Tor, also known as an Onion Router, is indeed the largest global anonymized network technology, including over 7000 distinct domain controller endpoints located all over the globe. Various kinds of wrongdoings are increasing day by day such as terrorism, abuse of the child is increasing using the network. To stop this monitoring plan is needed to develop. To enable this all the hacking mechanisms along with the architecture were...
Enⅽrypteⅾ Traffiⅽ Anaⅼysis through Expⅼainabⅼe Ⅿaⅽhine Ⅼearning
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasool (Supervisor)
Abstract
Impressive progress in hardwares and developing encryption algorithms in last two decades are caused increase in using encryption protocols in network communications. In last decade, users use privacy preserving networks like Jap and Tor to protect their privacy. These networks protect users' data from eavesdroppers by using three-layer encryption and intermediate nodes between user and target website. Recent researches show that Deep Neural Networks can predict websites viewed by users with high accuracy. In other words, privacy preserving networks suffer from information leakage. In this research, we introduced some of the most powerful methods in encrypted traffic classification and then...
Preserving Data Utility in Applying Differential Privacy on Correlated Data
, M.Sc. Thesis Sharif University of Technology ; Jalili, Rasoul (Supervisor)
Abstract
Differential privacy provides a powerful definition for protecting data privacy by adding noise. Differential privacy mechanisms add noise to the responses of queries made to a database. Differential privacy challenges the learning of useful information from a dataset without leaking any information about the individuals present in that dataset. However, studies have shown that these mechanisms make assumptions about the data that, if not met, can lead to privacy leaks. One of these assumptions is the lack of correlation between data. If an attacker is aware of the correlation between data, common mechanisms cannot guarantee differential privacy.This thesis proposes a solution for adding...
Text Separation of Single-Channel Audio Sources Using Deep Neural Networks
, M.Sc. Thesis Sharif University of Technology ; Motahari, Abolfazl (Supervisor)
Abstract
The problem of separation of audio sources is one of the oldest issues raised in the field of audio processing, which has been studied for more than half a century. The main focus of recent research in this field has been on improving the sound quality resulting from the separation of sound sources with the help of deep neural networks. This is despite the fact that in most applications of audio source separation, such as the application of meeting transcription, we do not need the separated audio of people. Rather, we need a pipeline of converting overlapping speech to text, which, by receiving the audio in which several people have spoken, outputs the text spoken by the people present in...