Flexible access to video streaming

This paper presents a flexible access method for secure multicast streaming. In this scheme, a server segments a video into clips, and prepares the protected video by selectively encrypting the video clips off line. Proxies store the protected videos and distribute them as cable-TV programs. To decrypt a protected video or clip, a client sends to the server a request for the decryption keys. The server then generates an enabling block which enables the client to access video or clips in a period. Therefore, the present scheme enables the client to access a clip or video for a restricted number of dissemination times, but the server selectively encrypts the video only once, and the distributor performs no encryption at all.