Abstract: A document accessible over a network can be registered. A registered document, and the content contained therein, cannot be transmitted undetected over and off of the network. In one embodiment, the invention includes maintaining a plurality of stored signatures in a signature database, each signature being associated with one of a plurality of registered documents. In one embodiment, the invention further includes maintaining the signature database by de-registering documents by removing the signatures associated with de-registered documents. In one embodiment, the invention further includes maintaining the database by removing redundant and high detection rate signatures. In one embodiment, the invention also includes maintaining the signature database by removing signatures based on the source text used to generate the signature.