US Patent 7516322 Copy protection built into a network infrastructure

A method for a network infrastructure copy protection system. The method includes the step of applying a digital signature to a digital content file prior to transmission. Digital content files that are to be legitimately transmitted across the distributed computer network are modified by the application of digital signatures corresponding to the sender. As content files are transmitted across a distributed computer network, the distributed computer network examines the content files to determine whether they include the digital signatures. The examining is performed by hardware comprising the infrastructure of the distributed computer network. When content files include respective digital signatures, the content files are transmitted by the infrastructure. When the content files do not include the digital signatures, transmission of those content files not having digital signatures is blocked. The digital signatures are configured to identify the senders of the digital content files. The digital signatures can be logged within the distributed computer network to maintain a record of the digital content files as they are transmitted. The hardware performing the examining can be a plurality of routers or a plurality of cache engines within the distributed computer network.