Method for protecting data content

A method for protecting data content against illegal copying, wherein the data content is provided by an entertainment system and is output to output units in an authorized playback environment for playing back the data content, the method comprising:

• transmitting the data content in the authorized playback environment, wherein the interior of an aircraft is provided as the authorized playback environment, from the entertainment system to an output unit, and
• adding an interference signal to the data content,
• wherein noise is added as the interference signal comprising a passive audio noise cloak and a phase shifted interruption noise based on specific and identifiable background noises in the authorized playback environment,
• wherein the passive audio noise cloak is configured such that the noise is not subjectively perceivable in the authorized playback environment due to constant background noises in the authorized playback environment and the phase shifted interruption noise is adapted to enable significant reduction of interference by the specific and identifiable background noises in the authorized playback environment;
• wherein the interference signal is specifically adapted to ambient conditions in the authorized playback environment and is configured such that during playback of the data content outside the authorized playback environment a perceivable disruption is induced by the passive audio noise cloak and phase shifted interruption noise, which is not perceivable during the playback of the data content inside the authorized playback environment because of the background noises of the authorized playback environment.