A framework for protecting personal information and privacy

User’s security and privacy are core issues of network applications. This paper proposes a privacy protection model to evaluate property risk of users, which takes into account both sensitivity of the property and requester’s level of assurance. Furthermore, the sensitivity of the property is evaluated by problem of expectation–maximization algorithm. Experiments show that the optimal size of samples for EM is relatively small, which indicates the high efficiency of the algorithm. The proposed privacy protection model cannot only assist users to do correct authorization, but also benefit the privacy reservation of users in online service. Copyright © 2015 John Wiley & Sons, Ltd.