A Virtual Organization (VO) consists of some real organizations with common interests, which aims to provide inter organizational associations to reach some common goals by sharing their resources with each other. Providing security mechanisms, and especially a suitable access control mechanism, which enforces the defined security policy is a necessary requirement in VOs. Since VO is a complex ...

Nowadays, users of information systems have inclination to use a central server to decrease data transferring and maintenance costs. Since such a system is not so trustworthy, users' data usually upkeeps encrypted. However, encryption is not a nostrum for security problems and cannot guarantee the data security. In other words, there are some techniques that can endanger security of encrypted d...

threats are one of the most fundamental problems of our modern societies that daily will affect citizens in urban spaces. this becomes more problematic when the people in their everyday living spaces encounter with behaviors that cause lack of security and should have been feel comfort and their families used these spaces freely. this causes many problems for citizens. in today cities because o...

explanation and evaluation of the book “rational choice and security studies, stephen walt and its critics”, edited by brown owen and lynn josomiller, has taken place in fact in the direction of exploration of the knowledge of security studies in international relations. in terms, examination of walt’s rational choice approach, and the formal-mathematical model, can help us to present a clear a...