Patent ID: 7058810

Claim:
A data terminal equipment for use in an information providing system where a server provides content data stored therein to said data terminal equipment which is placed on an information user's side for retrieving the content data through a communications network, said data terminal equipment comprising: an index retrieval part operable to retrieve index data indicating the content data prior to retrieving the content data; an authentication part operable to authenticate the content data by using the index data retrieved by said index retrieval part; and a content retrieval part operable to transmit a retrieval request for retrieving the authenticated content data to the server only if said authentication part has confirmed authenticity of the content data, and to receive the authenticated content data from the server, wherein: the content data is assigned a locator indicating information for specifying a storage location thereof; the index data includes embedded data in which the locator is embedded as an electronic watermark by an authorization agency; and said authentication part is operable to extract the locator from the embedded data included in the index data retrieved by said index retrieval part, and to confirm the authenticity of the content data if the locator is successfully extracted.