抄録
A lot of new broadcasting services using communication channels have been developed and structures of conventional content distribution and broadcasting services have been gradually changed. For example, broadcasting services were not bi-directional, but now, TV sets have Internet connection. This means that bi-directional and enriched broadcasting services may be possible. Content copyright protection is an issue also in such services. Several protection techniques have been applied for the purpose, but often broken. In addition, according to the change of the service structures, new security requirements have arisen and new security technologies are required.
New security technologies developed to improve the current ones and to meet the requirements of new services are described in this paper. Moreover, trends in state-of -the-art studies and future outlook are described.
