A technique for preventing malicious observance of private information includes presenting, via a graphical user interface, a visible input cue for user input. The visible input cues is associated with an expected input value that differs from the visible input cue. The technique further includes determining a correspondence between the visible input cue and the expected input value before the visible input cue is selected. The correspondence indicates how the visible input cues differs from the expected input value. The technique further includes generating an invisible output that indicates the correspondence between the visible input cue and the expected input value and detecting a selection of the visible input cue via the graphical user interface. The technique further includes using, as the user input, the expected input value instead of the visible input cue in response to the selection of the visible input cue.