Nowadays, people carry their phones every where; hence, their phones see lots of private information. If the phone camera is exploited by a malicious spy camera app, it may cause serious security and privacy problems. For example, the phone camera may record a user's daily activities and conversations, and then send these out via the Internet or multimedia messaging service (MMS). Secret photography is not only immoral but also illegal in some countries due to the invasion of privacy. Nevertheless, a phone camera could also provide some benefits if it is con-trolled well by the device owner. For example, when the owner wants to check if someone has used his/her phone without permission, the phone camera could be used to record the face of an unauthorized user. Besides, it can also help the owner find a lost phone