DATA ENCRYPTION METHOD, DATA ENCRYPTION PROCESSING PROGRAM, AND INFORMATION PROCESSOR

PROBLEM TO BE SOLVED: To solve the problems wherein content such as video images, sound, data is distributed from a center such as a broadcasting station to a terminal such as a cellular phone, however, there is also paid content or the like in the data, a mechanism of limited broadcasting called CAS is used so as to allow only a terminal with a right to receive and view the data, and in the CAS, a block encryption Multi 2 is used for concealment of the data, however, when it is intended to conceal content data by stream encryption to speed up processing, it is difficult to reduce a loss of the communication data in digital broadcasting. SOLUTION: This data encryption method is provided with a means for considering the maximum value of packet length of distribution data as unit length, sectioning the distribution data and a key stream to the unit length, concealing data with the unit length sectioned in packet order to be transmitted, from the head of the key stream, and suitably adding information for drawing timing of synchronization for synchronizing the data with the key stream. COPYRIGHT: (C)2011,JPO&INPIT