A client and one or more information retrieval (IR) engines, such as a search engine, may be in communication with each other via a network. A computer may read index information associated with at least a portion of an audiovisual object, the index information structured to be used in an index database of a search engine system. The computer may obfuscate at least a portion of the index information so that the intelligibility of the contents of the index information is reduced, and may transmit at least some of the obfuscated index information to the search engine system.