Implementation of H.264 transcoding & selective encryption of bit stream

CAS is positively necessary to streaming service such as IPTV and VOD, charging cable TV broadcasting channels, charging satellite broadcasting channels and so on . CAS system must show clean images to authorized users and have unauthorized users unable to enjoy the images normally. To make these environments, algorism that costs less additional expenses is needed, encryption is suggested as the method. In this paper, optional encryption of H.264 image was implemented for authorization system. Suggested method is to transcode the contents of various formats, convert into YUV format, compress it using H.264 codec and encrypt the particular part following needs. By the experiment, unauthorized users without encryption key cannot see the images properly, and that when make the intensity of encryption high, playing was possible but recognition of the images was not possible is recognizable. Also, encrypting the image of 300 frames took 71.3 seconds on the average, so being very fast is recognizable, too. Suggested contents are usable to the areas of user authorization and copyright protection in streaming service such as IPTV and VOD.