Sharif Digital Repository

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... 

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... 

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... 

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,... 

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...