Sharif Digital Repository

One of the security issues in data outsourcing scenario is the enforcement of data owner’s access control policies. This includes three challenges; 1) the average number of keys needed to access authorized resources, 2) efficient update of policies, and 3) confidentiality of data owner’s access control policies. Most of the existing proposed solutions address only one of these challenges, while they impose high overhead on both the data owner and users. Such an overhead prevents the model to be implemented in practical applications. In this thesis, we propose an approach to address all the aforementioned challenges with acceptable overhead. In this approach, which is based on selective... 

Due to the strategic importance of IT, there exists an undeniable need for a systematic analysis before deciding whether or not a particular IT process should be outsourced. A study that provides a systematic analysis for evaluating components of the company's IT for outsourcing may be useful to practitioners. In this research, analytic hierarchy process (AHP) is proposed as a suitable technique for analyzing information systems outsourcing decision. An IT outsourcing case is used to demonstrate the usefulness of the proposed approach. "Super Decisions" is used to implement the AHP  

Data outsourcing As a cloud service, it is a solution to reduce the cost of data storage and management in small and medium organizations. One of the main concerns in this area is the privacy of data owners and the non-disclosure of information by curious (albeit trusted) public cloud service providers. Resolving this issue requires encrypting the data before sending it to the cloud server. Transferring all encrypted data to the cloud server and performing various queries after encryption imposes a lot of time, computational and storage overhead, which destroys the philosophy of outsourcing. One of the open research issues is the processing of join queries over encrypted data by the cloud... 

Data outsourcing is an approach to delegate the burden of data management to external servers. In spite of its clear advantages, data outsourcing requires security assurances including data confidentiality, query result correctness, and access control enforcement. Research proposals have identified solutions with disparate assumptions for different security requirements. It is a real obstacle towards having an integrated solution through the combination of existing approaches. The practicality of data outsourcing to the cloud is seriously affected by this challenge. In this thesis, a unified view based on secret sharing is proposed to simultaneously achieve confidentiality, correctness, and... 

In the secure data outsourcing scenario, verification of the reply of an unreliable server includes assessing the authenticity, completeness and it’s integrity. In this thesis, an efficient method, with emphasis on freshness, has been introduced to evaluate the correctness of the replies from a server. It takes in hand different application needs, inherent differences in the data, and different update mechanisms. This method evaluates freshness by using timestamps alongside the data being out sourced. Due to the requirement of verifying not only the freshness of the response, but the correctness of the timestamps as well, two general methods for evaluating and verifying the responses were... 

In recent years, there has been a trend toward outsourcing data to the cloud provider. These companies must tackle the data security challenges. Generally these parties are assumed to be honest but curious. In past years, the research communities have been investigating different solution to ensure confidentiality.
In addition to data confidentiality access and pattern confidentiality is a high-priority issue in some cases so. potential adversary should be unable to drive information from the observed access pattern to the outsourced data. Despite the fact that there are more investigation in the field of data confidentiality, concern over data security are the rise in outsourcing data,... 

The ever-increasing volume of data and the lack of computational and storage facilities have caused a managerial challenge to organizations. The existence of these challenges on the one hand and the increase of storage services on the other hand have compelled the organizations to delegate their storage and management of data to the server providers of cloud storage services. The outsourcing of data to servers obviates the need for purchasing exorbitant storage equipment and recruiting professional workforce in the organization. Since the organization’s data will be kept outside the organization’s ambience in case of using such services in form of outsourcing, and the data will not be under... 

Cloud Manufacturing is a new paradigm which under development and has been introduced as one of the promising models for providing ubiquitous, convenient, on-demand network access to a shared pool of configurable manufacturing resources (e.g, networks, servers, facilities, applications, robots, machines and services) that can be rapidly provisioned with minimal management effort and service provider’s interaction. Cloud Manufacturing is defined based on Cloud Computing. Like the Cloud Computing, Cloud Manufaturing offers a service-oriented architecture that is based on information technology (IT) in which each manufacturing resources is expressed as a service. For providing a... 

Outsourcing is currently a challenging issue in the auto industry. On one hand, outsourcing has be-come a competitive imperative for automakers due to its significant benefits. On the other hand, it involves many aspects of risks that could potentially hurt core competencies of a firm. As such, in the auto industry, it is highly critical to make optimal outsourcing decisions for which an integrated framework offering a holistic view seems quite necessary. In this thesis, based on four fundamental research questions of “Who?”, “What?”, “Whom?” and “How?”, an integrated framework for outsourcing in the auto industry is developed in order to identify effective outsourcing factors and associated... 

Recently, many organizations outsource their data on an external server to rescue the trouble of data maintenance. But, data owners do not trust in the external server to enforce defined access control policies. In recent years, many researches was dedicated to cryptographic access control on outsourced data, in order to solve this problem. We introduce a method based on Attribute-based Encryption to enforce access control on outsourced data. In this method we consider policy updating and administrative access control. As a result The owner is not only able to change access control policies on outsourced data but also to define administrative rights (grant/revoke) for some admin users. Our... 

Data outsourcing provides cost-saving and availability guarantees. However, privacy and confidentiality issues, disappoint owners from outsourcing their data. Although solutions such as CryptDB and SDB tried to provide secure and practical systems, their enforced limitations, made them useless in practice. Inability in search on encrypted data, is one of the most important existing challenges in such systems. Furthermore, the overhead of mechanisms such as FHEs, removes them from considering for any practical system. Indeed, special purpose encryptions would be the only usable mechanisms for such purposes. However, their limited functionality does not support some important required... 

With the help of cloud computing, easy and fast access to a wide range of computing resources through the network is provided for a wide range of users. Cloud computing, on the other hand, faces security challenges in protecting users' privacy and access control because the cloud service provider is not a trusted entity, so it is possible to access or disclose sensitive data. Various solutions have been proposed to simultaneously meet the above two security requirements. The most well-known solution in this field is "Attribute-Based Encryption".In this dissertation, after reviewing the existing schemes to respond to the obstacles to implementing attribute-based encryption, an attribute-based... 

One of the security issues in database outsourcing scenario is the correctness of the query results. Correctness verification includes integrity, completeness and freshness of the results. Most of the proposed approaches for correctness verification impose high overhead on the components of the scenario which prevents the scenario to implemented in practical applications. In this thesis, we have proposed a probabilistic approach which imposes acceptable overhead for correctness verification of returned results of service provider. The approach uses the previous behavior of the service provider to calculate a trust value toward it which is used to adjust the imposed overhead. In other words,... 

Dynamic searchable encryption schemes enable keyword search query and update operations on encrypted data. One of their applications is to use them in cloud storage services that allow the client to store, search and update data on an external server. Due to the importance of efficiency in real-world applications, retrieving information in searchable schemes involves leakage of some information such as search and access patterns. However, with the addition of update operations (insertion and deletion), more leakages are considered for these schemes. In this regard, reducing the amount of information disclosed to the server is necessary. For this purpose, forward and backward security... 

Regarding to globalization concept, all companies around the world can communicate with each other, share their technologies and also compensate their production deficiencies. To achieve this goal, cloud manufacturing system have been proposed and investigated. One of the most important issues in cloud manufacturing is focusing on the service composition, in which a composition of cloud services is determined to meet customer demands. Also due to the distribution of the resources in the different points and geographic locations, considering to the production and routing which previously have been studied in the classical space is very important. Considering this, the problem is as follows:... 

Decreasing cost, enhancing quality, increasing the customer satisfaction and the productivity to gain farther market shares are among the reasons for urging the companies to outsource their needs. In this study the definition of outsourcing, its advantages and weaknesses and the risks associated with it are presented and then models for decision making on outsourcing and its implementation process are discussed. As a scope for this mention, then the evaluation of outsourcing procedures for the paint shops is selected and studied. A model for the case is also presented. The case study is undertaken in Iran Khodro's paint shop during the years: 1379 – 1384 as a practical case. We can summarize... 

Infrastructural costs of data management, have led people and organizations to outsource their data. This approach is facing with some significant security challenges and risks. The goal of this research, is to present an architecture for secure outsourcing of data in a way that used methods, storage processes, query processing methods and access control mechanisms work together to preserve confidentiality and integrity of outsourced data. In this architecture, the main challenge is transparent placement of some components between client and server in order to prevent user from being aware of communication with a secured server. In order to create this degree of transparency, we need to pay... 

Recently many organizations outsource their data to an external server due to easier data maintenance. One of the security issues in data outsourcing scenario is the enforcement of data owner’s access control policies. This includes some challenges; namely, the number of keys needed to access authorized resources, efficient policy updating, write access control enforcement, user and data owner overhead, and preserving confidentiality of data and policies . Most of the existing proposed solutions address only some of these challenges, while they impose high overhead on both the data owner and users. Moreover, most of them address enfrocement of policies in form of access control matrix and... 

In recent years, different cryptographic tools have been introduced for a wide range of cloud computing applications that can be classified based on a trade-off between performance and security. In this thesis, we introduced the private set operation schemes, and at their heart, private set intersection schemes, in the cloud computing platform. These schemes are of particular importance because they can be used as basic cryptographic schemes for a wide range of functionalities in the cloud platform. Using these schemes, the user can securely store datasets on the cloud, run set queries remotely and receive the desired results. To this end, we first modeled the syntax and the security notions... 

In recent years, one of the research interests is ensuring the integrity of computations done on data received from multiple data sources. Limited research has been done to ensure the integrity of computations that the output depends on data generated by different data sources. However, there are many solutions for systems that the input data is generated by a single data source. In this thesis, ensuring the integrity of multi-source aggregate functions and general functions are investigated in an untrusted server. To verify the integrity of aggregate functions, first of all, we present a construction for verifying the results of linear functions using the RSA signature. It should be noted...