Abstract
Cloud computing is an uprising field in information technology (IT) industry because of its performance, high availability, low cost and much more. The data leakage, lack of proper security control policy, and weakness in the data sentry are the main worries of the companies. So that a cloud data security models should be able to overcome all the possible issues of cloud computing, so as to provide the benefits of cloud computing and preventing the owner's data from all the risks associated. This paper focuses on two phases; the first phase is a discussion of the security functions that should be realized during building any data cloud model. A comparison of some designed cloud models is discussed as the second phase. The cloud models discussed are Wang scheme (2009), Prased scheme (2011), Sandeep K. Sood (2012), Xin Dong scheme (2014), and P. Lavanya scheme (2014) all of which are displayed and its security are discussed. A discussion of a number of possible security measures is our concern in this paper, which should be considered in any cloud based model. Recommendations are further given for proper security issues over cloud systems. (C) 2015 The Authors. Published by Elsevier B.V.