Techniques are described for protecting information in a convenient and useful way. A user transmits information from a mobile device to an ambient display, so that other users may receive the information from the ambient display. A display controller detects a presence of a potentially unauthorized user relative to the ambient display, and modifies the outputting of the information at the ambient display so as to hide portions of the information that should not be seen by the potentially unauthorized user. The information, including the hidden portion, is nonetheless output, using one of a plurality of output channels of one or more secondary devices, either to the user and/or the other users. In this way, authorized users may continue to receive the information, and, moreover, may input an indication as to whether an extent of the hidden portion is sufficient to provide adequate security with regard to the information.