Digital data content certification system, data certification device, user terminal, computer program and method therefor

Abstract

A file is created in which digital data and a certificate are integrated and content authentication for the digital data and the certificate are performed simultaneously. A data authentication device () is provided with: an original data receiving means which is communicably connected to a user terminal () and a timestamp provision device (), and receives original data to be authenticated from the user terminal (); an intermediate file creation means which creates an authentication file corresponding to the original data, and attaches the actual original data to the authentication file to create an intermediate file; a timestamp request means which transmits the intermediate file to the timestamp provision device (); a date/time security information acquisition means which receives from the timestamp provision device () date/time security information containing date/time information and a hash value for the intermediate file; an authenticated file creation means which embeds the received date/time security information in the intermediate file and creates an authenticated file; and an authenticated file transmission means which transmits the authenticated file to the user terminal ().