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Location-based services (LBSs) provide appropriate information based on users’ locations. These services can be invoked by an individual user or a group of users. Using these services requires users to reveal their locations; thus, providing uses’ location privacy during the use of these services is an important issue. There are many works to protect users’ location privacy. In this paper, we have reviewed the related works to provide the location privacy for a group of users during the use of LBSs. We have classified them into two categories: the first category consists of the solutions that protect an individual user location privacy through group formation, while the second category contains the specific solutions to provide group location privacy. We have then analyzed and compared the performance and security properties of the related works, and have identified the open issues and future works in this field.

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Doing a joint and secure computation on private inputs (Secure Multiparty Computation) is an interesting problem in the field of information security. The Millionaire problem is the first SMC problem in which two millionaires wish to know who is richer without disclosing their wealth. Then many problems have been defined in the field of secure multiparty computation. In this paper, the problem of secure multiparty summation is considered where a group of users wants to jointly and securely compute the summation value of their private inputs. We have reviewed and compared the related works in this filed; we have also identified the open issues and future works.
 

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In a verifiable database scheme (VDB), a client with limited storage resources securely outsources its very large and dynamic database to an untrusted server such that any attempt to tamper with the data, or even any unintentional changes to the data, can be detected by the client with high probability. The latest work in this area has tried to add the secure search feature of single keyword and multiple keywords. In this paper, we intend to add a range query to the features of this database. The scheme presented in this article provides the requirements of a secure search, namely the completeness of the search result, the proof of the empty search result, the lack of additional information leakage and the freshness of the search results, as well as the database with public verifiability. In the proposed scheme, the computational complexity of the client is not changed significantly compared with the previous scheme, but the computational and storage complexity of the server has increased which is justifiable by its rich resources.