To protect confidential data, a mobile device determines whether the mobile device is at a location susceptible to visual capture of confidential data entered into the phone by external cameras. The mobile device determines whether focus of a display is on a field in which confidential data is entered. If the mobile device determines that it is at a location susceptible to an external imaging device visually capturing confidential data input into the input field, then the mobile device activate a light source on a same side as the screen presenting the display.