Abstract: A Media Registration and Validation Service (“MRVS”) facilitates protection against unauthorized media sharing. In the media registration function, the MRVS receives, registers and stores one or more samples of media content defining source content. In the media evaluation function, the MRVS receives samples of media content (“examination content”) submitted for examination relative to the source content. The MRVS searches the database to determine instances of source content corresponding to the examination content, yielding corresponding content; and produces a report including indicia of the corresponding content. Protection against media sharing is thereby accomplished in one aspect by providing notice of registered source content to one or more prospective disclosers of corresponding content (including, without limitation, the submitters of examination content); and in another aspect, the prospective disclosers can rely on the notice to decide whether or not to disseminate their corresponding content.