Recently, software defined networks have been introduced for innovation and flexibility in computer networks. They are widely used in infrastructure networks and data centers. Using these networks has advantages such as scalability, efficient bandwidth usage, reducing control traffic, better traffic engineering and etc., which are mainly due to their programmability. There are also some security challenges that often arise from the same property. Software defined networks reliability compared to traditional network reduces due to these challenges. Therefore, if software defined networks are not design based on a security architecture, they will be vulnerable against known cyber-attacks such as DDoS, spoofing, information disclosure and etc. In this paper, software defined network security challenges and corresponding solutions are reviewed. Moreover, some applications of software defined networks for security including network traffic separation, network flow access control, and secure routing are mentioned. In order to do security testing and evaluation of relevant security solutions we have explained how these networks are simulated.

Cloud environment are known as a revolution in IT industry in the recent decade and many organizations have used this service for data processing and data storage. Despite of fast growing and numerous advantages, some organizations still do not use this service due to security problems and privacy issues related to storing sensitive data on the untrusted cloud servers. Access control management utilizing encryption techniques is one of the most common methods to solve these kinds of problems. Attribute based encryption is a new cryptographic model which uses descriptive attributes and access structures for managing access control. This article discusses the most recent methods of access control in cloud environment using attribute based encryption. We classify these protocols with respect of efficiently and security features. Finally, all the strengths and weaknesses points of reviewed articles are discussed and a comprehensive security and practical comparison is presented.

Data collection and storage has facilitated by the growth in electronic services, and has led to recording vast amounts of personal information in public and private organizations' databases. These records often include sensitive personal information (such as income and diseases) and must be covered from others access. But in some cases, mining the data and extraction of knowledge from these valuable sources, creates the need for sharing them with other organizations. This would bring security challenges in users' privacy. “Privacy preserving data publishing” is a solution to ensure secrecy of sensitive information in a data set, after publishing it in a hostile environment. This process aimed to hide sensitive information and keep published data suitable for knowledge discovery techniques. Grouping data set records is a broad approach to data anonymization. This technique prevents access to sensitive attributes of a specific record by eliminating the distinction between a number of data set ‌records. In this paper an overview of privacy preserving Data Publishing Techniques will be presented.

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.

Due to the increasing use of smartphones among different groups of users in society as well as various capabilities that mobile devices provide for users, ensuring the security of smartphones is very important. Distribution markets of apps compromises the security of smartphones. Appstores play an important role in ensuring the security of smartphones and, if security requirements will be followed then they can protect users against malware developers. For this purpose, it is essential to identify security risks for this part of the app ecosystems. In this document, security risks raised in the app ecosystem in the field of app distribution markets have been explained. 
 

validation among Users, Stockholders, and delivering important and various services with high availability are part of import dimensions of local search engines. This paper provided a comprehensive research result on Combination of security control tools with main components of local search engines, like crawler, ranker, Indexer and security requirements Consideration in all phases of software development life cycle. We organize the existing research works on securing local search engines based on combination of security standards relevant to software development life cycle of systems with key components of local search engines to help developers, software project managers for implementing security controls and requirements properly.
 

Not only election is one of the significant issues in democratic societies, but also it can be used in commercial association such as stock market and it has a noteworthy feature to determine the board of the directors. According to progresses in cryptographic topics and asymmetric encryption systems, tremendous attempts have been made in the design of protocols for electronic elections. However, all of the designed protocols have either high complexity or weaknesses in security features. Since the majority of electronic election schemes are dependent on a number of honest persons, they are practically difficult. In addition, in most of them, voters will play a key role in producing ballot. If someone imposes compulsory, privacy will be lost or the voter will be able to provide a receipt to show the content of his vote, and this in turn, vote-buying and immoral issues will be appeared. 
In this paper after, evaluating the security features of an electronic election scheme, an election protocol based on homomorphic encryption, will be expressed, and  the difference between the receipt  protocol and receipt-free protocol will be  examined.
 

Abstarct- The local search engine systems is one of the indicators of IT industry development in all countries. The safety of these systems arises according to its specific position, with providing users to access to right information in the least possible time. The most effective measures to secure this type of application are assessment and risk management in the early stage of software security. It consists of a set of steps that will help a software team in the applications management during the development process. In order to reduce the risk of this type of systems responce to risk approach is selected. The main objective of this article is assessment and risk management based on information collected from designed questionnaire. As well as to identify important risks, security controls and NIST methodology are used and the results of calculations of the risk level are provided on the basis of known fields.

Devices such as wireless sensor networks and RFIDs have limited memory, power and energy. They have security requirements so that the usual implementation of cryptographic algorithms is not appropriate for them and leads to high consumption of resources. One solution is designing new lightweight algorithms that have a lower security level than standard algorithms. The second solution is implementing standard algorithms such as AES block cipher as a lightweight algorithm. In this type of implementation, some techniques such as resource sharing, S-box implementation with combinational circuits, mapping computations finite fields from one base to another base and on the fly computation are used. In this paper, the most important lightweight implementations of AES are evaluated. The criteria considered for this evaluation include gate count, the number of clocks required for an encryption/decryption operation, throughput, power, energy and the combination of themes. Studies show that we can use standard encryption algorithms in applications with limited area between 2000-3000 GE and a small amount of energy, for example a few PJ. Some of these successes are achieved due to advancements in CMOS circuit technology and some others are the result of designing suitable hardware architecture, exact scheduling of cryptographic operations and efficient use of resources.