To date the considerable computation and storage power of clouds that have attracted great attention from mobile users and mobile service providers over the past few years. The convergence of mobile devices and clouds that leads to a brand new era of could-based mobile applications. It brings long-listed advantages for mobile users to get rid of the constraints of mobile devices (including limited mobile memory, data processing ability and battery). However, mobile clouds yield new security and privacy risks in open network setting. This survey paper attempts to introduce security risks on mobile clouds in the view point of applied cryptography.

As wireless networks flourish, Internet users can access social network platforms (such as Facebook and Twitter) through personal electronic devices anywhere and anytime. However, because users often deploy social network platforms in a public network setting, a common concern remains about how to guarantee privacy for photo sharing. Although most platforms aim to protect such privacy, few are able to reach the goal. This work focuses on an interesting potential privacy risk, called the deletion delay of photo sharing, by pinpointing and investigating the risk's existence in some well-known social network platforms.