Database outsourcing is an idea to eliminate the burden of Database management from organizations. Since data is a critical asset of organizations, preserving its privacy from outside adversary and untrusted server should be warranted. In this paper, we present a distributed scheme based on storing shares of data on different servers and separating indexes from data on a distinct server. Shamir's secret sharing scheme is used for distributing data to data share servers. A B+-tree index on the order preserved encrypted values for each searchable attribute is stored in the index server. To process a query, the client receives responses including record numbers from the index server and asks these records from data share servers. The final result is computed by the client using data shares. While the proposed approach is secure against different Database attacks, it supports exact match, range, aggregation, and pattern matching queries efficiently. Simulation results show the prominence of our approach in comparison with the bucketing scheme as it imposes lower computation and communication costs on the client.

Correctness veri cation of query results is a signi cant challenge in Database outsourcing. Most of the proposed approaches impose high overhead, which makes them impractical in real scenarios. Probabilistic approaches are proposed in order to reduce the computation overhead pertaining to the veri cation process. In this paper, we use the notion of trust as the basis of our probabilistic approach to e ciently verify the correctness of query results. The trust is computed based on observing the history of interactions between clients and the service provider. Our approach exploits Merkle Hash Tree as an authentication data structure. The amount of trust value towards the service provider leads to investigating just an appropriate portion of the tree. Implementation results of our approach show that considering the trust, derived from the history of interactions, provides a trade-o between performance and security, and reduces the veri cation overhead imposed on clients in Database outsourcing scenarios.

The increasing amount of information as well as lack of existence of sufficient computational facilities and storage in organizations have caused various management problems. These problems on the one hand and the rapid expansion of storage services on the other hand have made different organizations to use cloud storage service providers in order to store and manage their organizational information. Using such services, causes organizational information to be stored outside of the organization environment and therefore the owner have less control over its information. Therefore, security concerns will be raised. Many security solutions are proposed to deal with these security concerns, but most of these solutions have focused on a particular aspect of data life cycle such as storage phases. Understanding and considering the data life cycle as well as the challenges and the opportunities facing organizations leads to provide appropriate solutions to overcome security concerns. This paper aims at discussing and analyzing the challenges and opportunities facing organizations using data outsourcing services, and then a new architecture for the Database outsourcing with regards to the data life cycle will be presented.

In Data outsourcing, the owner surrenders his data management operations to an external provider which receives user queries and answers them. Besides, data may be of great importance to owners while the external provider may not be trustworthy. Thus, providing data privacy and integrity of user queries have to be considered. Here data privacy means that owner's data must not be revealed to service provider; and query integrity means that the result set returned to users must be sound, complete, and up-to-date. Different methods are proposed to handle mentioned goals with their own advantages and disadvantage, namely encryption usage, private information retrieval (PIR) and data distribution. In this article, we have proposed an approach to gain mentioned goals. Our approach provides better performance and it also provides data privacy and integrity of queries.

In the outsourcing of the data, the management of the data is delegated as a service to the external service provider. However, security issues related to outsourced data create many challenges in this regard. So far, many studies have been done to increase security, each with its own advantages and disadvantages. In this research, assuming the unreliable external service providers in the cloud and relying on cryptographic mechanisms and secret sharing techniques, a method has been proposed to provide the security of outsourcing data, and even provide them with keep hidden from external trusted service providers. In the proposed method, lattice-based encryption is also used. Using lattice encryption, data security is strongly guaranteed against quantum attacks. The evaluation of the proposed method in this paper explains the security of outsourced data. It is also shown that runtime, bandwidth and memory usage of the proposed method are improved compared to previous methods. Meanwhile, in this way, the information is broken down into the number of service providers and each part is sent to a service provider, thereby reducing the bandwidth and memory by eliminating the repetition of the data.