System, device, and method of providing authenticity and rights verification mechanism for media content and for its derived versions. A media authenticity server is configured to receive a content item, and to generate for it a record having a unique content identifier and indications of permitted modifications, and optionally also copyright information usage restrictions. The media authenticity server authorizes or blocks modifications requests regarding the content item. The media authenticity server tracks and logs the permitted modifications performed on the content item, and makes this log available for inspection to end-user devices via a web browser or via a content consumption application. Optionally, playback or consumption of a modified version of the content item is blocked, or is accompanied by a warning message, if the modified version is not associated with an authenticated log of permitted modifications.