This paper proposes the IP Multicast-enabled Drop Groups (I-DG) protocol as a solution to the problem of efficiently and securely disseminating information to a large number of subscribers in the Internet. The I-DG protocol uses an appropriate IP multicasting protocol as the base and addresses the problems introduced by large scale data dissemination. I-DG provides dynamic subscription to multicast data, efficient secure subscription in IP multicasting, and proposes a solution to content organization in broadcasts.