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  The Cloud computing is a low-cost high performance model of computing services in response to the needs of users of Information Technology. Current security and privacy challenges in cloud environment have led to distaste some users and organizations to apply cloud instead of traditional infrastructures. Although many prevention efforts and acts are performed in current network architectures, detection and tracing of the attacker is necessary after the event is occurred. But current architecture of cloud computing does not satisfy the cloud forensics needs. Therefore, in this field the cloud forensic investigation have many different challenges. Regarding the low cost and high performance services of cloud computing, for the sake of security issues it can never be ignored. So far several solutions have been proposed regardingcloud’s security issues based on dynamic and elastic nature of cloud computing and legal issues. The main goal of this survey is to classify and and explore the cloud forensics issues and challenges.

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With emerging of the Internet, the way we communicate with each other has fundamentally revolutionized. The second development wave of the Internet is not about people, but will be about smart connected devices. Although more than a decade passes from the proposing of "Internet of Things" concept, the deployment of this concept has been done slowly for various reasons such as lack of required technologies development and security challenges. We must spend more time to understand the security challenges and available solutions, when we speak about smarter environments and technologies such as IoT. In this paper, we attempt to analysis existent threats and vulnerabilities in the area of security and privacy of Internet of Things using a systematic approach, while presenting a survey of the solutions proposed in the literature. Finally, research opportunities of this area will be discussed.

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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.

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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.

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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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The Identity Management System (IDM) is a set of policies, rules, procedures, and systems that manage authentication, access control, and audit activity based on digital identity. In the Identity Management System, given the storage of user identity attributes in the identity provider, users will lose their physical and traditional control over their personal identity, and on the other hand, user attributes are subject to more attacks from The inside of the system and the external attackers. Therefore, to ensure user's privacy control is keeping awareness of the release of his / her  identity information, So providing security mechanisms in the area of privacy is essential. The current mechanisms have failed to satisfy users confidence in maintaining the security and privacy associated with their identity information. The designs presented in this area will increase user intervention and involvement during system interactions , and the user must act as an interface role. The Problems of the proposed designs, the high computational burden on a part of the system. In this article, the process of improving privacy control and user awareness for solving problems has been investigated.

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Online social networks (OSNs) is one of the most popular medium for communicating, sharing, and publishing a considerable amount of information. OSN popularity often faces the challenge of dealing with unwanted messages and hidden malicious purposes in it. Based on recent studies, social network users can easily expose their confidential details with others. Misuse of this information can cause damage in virtual and real world. In this paper, main categories attacks are given on social network online security and privacy in four categories classic, modern, hybrid and children special attacks and ways that can be used to protect against different types of attacks used OSN users is the social network operators, security companies, and researchers are provided. Finally, eight ways to prevent these threats is presented.
 

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With the advent of cloud computing, data owners tend to submit their data to cloud servers and allow users to access data when needed. However, outsourcing sensitive data will lead to privacy issues. Encrypting data before outsourcing solves privacy issues, but in this case, we will lose the ability to search the data. Searchable encryption (SE) schemes have been proposed to achieve this feature of searching encrypted data without compromising privacy. This method will protect both the user's sensitive information and the ability to search for encrypted data. In this article, we review the various SE designs. In this review, we present the classification of SE designs: symmetric searchable encryption, public key searchable encryption, and search attribute-based encryption schemes, and then a detailed discussion of SE designs in terms of index structure. And provide search functionality. There is also a comparison of SE design analysis in terms of security, performance and security. In addition, we talked about the challenges, leading directions and applications of SE schemes.

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In recent decades, video surveillance systems have an increasing development that are used to prevent crime and manage facilities with rapid diffusion of  (CCTV)cameras to prevent crime and manage facilities. The video stored in the video surveillance system should be managed comfortably, but sometimes the movies are leaking out to unauthorized people or by unauthorized people, thus violating individual boundaries . CCTV cameras and video surveillance systems are needed today because of the increasing number of crimes, These cameras and video surveillance systems. but because of unsafe storage and data sharing methods, access to movies saved by unauthorized people is possible. The use of existing protocols and security techniques has already been defeated several times by the attackers. It requires an alternative system that should not only be highly secure but not changeable. Video stream generated by surveillance cameras play a crucial role in preventing crime in smart cities. CCTV cameras are necessary for a range of public applications in a smart city; they can become smart sensors that help ensure safety and safety. in this paper, we review the methods and articles presented in the context of blockchain application in visual surveillance systems and compare them.

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Financial transactions in Bitcoin are stored in a distributed database called the block chain. All transactions are publicly available for all network nodes with the aim of transparency and the possibility of verifying the correctness. But this blockchain transparency feature, exploited by transaction analysis techniques, can lead to the violation of users’ privacy and the disclosure of their identities. Researchers have proposed various techniques such as transaction mixing or fair exchange with the aim of improving privacy in Bitcoin transactions. In this paper, we present a new mixing scheme that overcomes some of the weaknesses of previous schemes. Obviously, in the proposed scheme, users can mix different amounts of Bitcoin in each round of the protocol implementation, which leads to achieving the result in a shorter time and at a lower cost. Also, this scheme is more resistant to denial of service attacks by malicious users.

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Data outsourcing to reliable centers for data maintenance, protection and accessibility is simple and low-cost and does not require physical infrastructure, hardware, software and human resources. However, real-world events and recent researches have shown that even reliable centers can abuse users' trust. For example, 1) make changes in the data they have, 2) delete them, or 3) make them temporarily/permanently unavailable. Data audit methods assure the data owners that the data recorded in the database is the same as the data sent by the user and reveals the changes made in it. But they only solve the first problem. In 2008, the introduction of a technology called blockchain, which had several attractive features such as transparency, immutability, and autonomy, caused the problems of many systems that needed the mentioned features to be solved. In this article, after reviewing and addressing several blockchain-based data auditing architectures and protocols, we review and analyze their general framework. Finally, we compare the reviewed works and specify some future horizons of this field.

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