Sharif Digital Repository

While data outsourcing provides some benefits, it suffers from new privacy and security concerns, mainly about the confidentiality and integrity of the stored sensitive data, as well as enforcing access control policies. Current solutions to these aims are not comprehensive and consider only one aspect of security requirements. A secure DBMS architecture is introduced that simultaneously considers confidentiality, integrity and access control enforcement requirements. The transparency of security functions from data owner, service providers, and applications facilitates the operationality of the solution.Additionally, a new indexing technique for character encrypted data is proposed that... 

The Internet of Things is one of the most common technologies in today's world where its security is an important issue. Lightweight authentication protocols are crucial for privacy preserving in Internet of Things (IoT). IoT authentication protocols must meet security requirements and resist against cryptographic threats. On the other hand, these protocols should be implementable for devices with constrained memory and computational power in this area and should not impose a heavy computational load on such devices. In some IoT devices, such as RFIDs, resource constraints are critical, such that using standard hash functions is not practical. In this applications, security requirements is... 

The internet of things is a network of interconnected things (people, electronic devices, mechanical machines, etc.) that are able to transfer data. The applications of internet of things in electronic health (eHealth) are becoming increasingly interested. Deployment of eHealth facilitates the access of users to healthcare services, and improves the quality of the services. Using cloud computing provides the accessibility of healthcare services, and enables a data owner to share his health data with doctors and healthcare service providers. Health data is considered sensitive. So, leakage of any information about it endangers data owner privacy. Attribute-based encryption is a cryptographic... 

Privacy preserving data mining helps organizations and companies not only to deal with privacy concerns of customers and regular limitations, but also to benefit from collaborative data mining. Utilizing cryptographic techniques and secure multiparty computation (SMC) are among widely employed approaches for preserving privacy in distributed data mining. The general purpose of secure multiparty computation protocols to compute specific functions on private inputs of parties in a collaborative manner and without revealing their private inputs. Providing rigorous security proof of secure multiparty computation makes it a good choice for privacy preservation, despite of its cryptographic... 

The expansion of technology and the increasing use of mobile devices and smartphones have aected various aspects of personal and social life. These include the use of personal mobile devices in enterprise environments called BYODs have a number of positive and negative eects. On the one hand, it would be more cost-eective for an organization or business environment for users to use their own devices, but on the other hand, it poses numerous security and information challenges that are important to manage. These include disrupting the user’s privacy or disseminating organization information to personal devices and thus violating the organization’s security policies. In this study, a model is... 

The emerging applications of machine learning algorithms on mobile devices motivate us to offload the computation tasks of training a model or deploying a trained one to the cloud or at the edge of the network. One of the major challenges in this setup is to guarantee the privacy of the client data. Various methods have been proposed to protect privacy in the literature. Those include (i) adding noise to the client data, which reduces the accuracy of the result, (ii) using secure multiparty computation (MPC), which requires significant communication among the computing nodes or with the client, (iii) relying on homomorphic encryption (HE) methods, which significantly increases computation... 

In the problem of Distributed Multi¬User Secret Sharing (DMUSS), in which K users are connected through some error¬free links to N distinct storage nodes with the same size M information unit, the users desire to retrieve their corresponding secret message through an arbitrary set of accessible storage nodes. A trusted master node, which knows all of the secret messages transmits correctly and privately, the messages with a means of coding. The capacity of Distributed Multi¬User Secret Sharing is the supremum of all achievable schemes satisfying privacy and correctness conditions. In this thesis we have investigated two notions of privacy namely, individual and joint privacy. Individual... 

Vehicle Ad-hoc Network (VANET) is a type of mobile Ad-hoc network (MANETs) which vehicles are mobile nodes of this network and it can be used for various applications such as secure data sharing between vehicles, sending road information to vehicles, traffic controlling and reducing road accidents, also primary types of these networks are implemented in some systems such as “Waze” and “Balad”. On the other hand, if the security requirments are not provide in these networks, attackers can use this network to cause disruptions in this network, including intentional accidents, so providing security requirements in these networks seems necessary. Data authentication and preserving privacy of the... 

Cloud computing has a significant role in expanding applications of the Internet of Things (IoT). Currently, applications such as virtual reality and augmented reality require low latency, which is not achievable using traditional cloud computing in some scenarios. Edge computing is a new approach in IoT, which solves some of the limitations of the cloud computing by extending and developing its operations. Reducing response time and network traffic are some of the most important achievements of edge computing. Despite of its numerous advantages over cloud computing, edge computing faces serious challenges such as virtualization, implementation infrastructure, resource allocation and task... 

Lightweight clients are a type of blockchain users who do not store all the blocks in the blockchain due to limited resources. These users store only a small part of each block and when needed, request transactions from full nodes that store the entire blockchain. These users have no role in block validation and only want to receive transactions related to their addresses with proof of the inclusion in the block from full nodes.Since light clients rely on full nodes for receiving transactions, their privacy against full nodes is important. The current implementation of Bitcoin uses Bloom filters for privacy, but this offers very little privacy to the users.In this thesis, we study the... 

Nowadays, intelligent transportation systems have become possible and practical with the help of vehicular ad-hoc networks. This network is a subset of mobile ad-hoc networks introduced and studied separately due to its unique properties. With the help of vehicular ad-hoc networks, the level of road and drivers safety is increased and safety messages can be sent to road side units or other vehicles, so real-time is one of the main requirements of these networks. Other advantages of implementing such networks include providing entertainment and internet access services.On the other hand, these networks face various challenges, including routing data packets, preserving security requirements,... 

The security and convenience of digital payment methods have made them an essential part of people's daily lives. As a result, the possibility of using these methods in an offline environment without the need to communicate with the payment service provider is of great importance. To make this possible, a digital currency system should enable users to securely control their assets without the help of an intermediary and act according to established laws to combat financial crimes. Otherwise, this system will not be usable by the public or on a large scale. To solve this problem, a scheme with the possibility of offline payment by customers, prevention and detection of double spending by... 

The multi people tracking is considered a fundamental problem in computer vision, which has received considerable attention from academic and commercial fields. This issue deals with a set of proposed methods that track the movement path of several humans in a video-like sequence. The problem of multi people tracking is the foundation of other computer vision problems, including human gesture estimation, motion recognition, and behavioral analysis, and is mainly used in emerging fields such as automatic car driving, smart security, service robots, etc. Although many methods have been proposed and investigated to solve the above problem; But there are still serious challenges, such as severe... 

large-scale data collection from multiple sources to a single entity, such as a cloud provider, poses a challenging problem for implementing centralized machine learning algorithms. Constraints such as privacy protection and restrictive access policies that prevent accessing personally identifiable information hinder the development of centralized machine learning algorithms in important and sensitive domains like healthcare. However, from early disease detection to discovering new drugs, leveraging artificial intelligence in this domain is a fun-damental necessity. As a potential solution, federated learning has been proposed, allowing data owners (users) to jointly train a shared machine... 

The rapid evolution of artificial intelligence (AI) technologies has led to the widespread adoption of AI systems in diverse research and industrial fields. Deep neural networks, at the forefront of AI's power, demonstrate high performance by leveraging large volumes of training data. However, acquiring such vast amounts of data requires collaboration among individual data owners, who may have concerns about privacy. To address these concerns, various privacy-preserving methodologies have been proposed. These methodologies share a common goal of striking a balance between preserving privacy and maintaining data utility. This study aims to explore and analyze these privacy protection...