Condition access chip of digital television and realization method of condition access

The invention discloses a condition access chip of a digital television and a realization method of condition access. The condition access chip comprises a central processing unit, a transmission flow processor, a nonvolatile memory and a control word decryption module; a DMA (Direct Memory Access) controller is used for controlling the control word decryption module to finish decryption operation on a control word according to a task chain table which is stored in the nonvolatile memory; and a storage protection unit is used for carrying out safety configuration according to configuration information obtained by the DMA controller from the nonvolatile memory, and then protecting a bus address interval of the chip through constructing a safety island. According to the invention, through constructing the safety island and configuring the task chain table of the DMA controller, an attacker cannot execute an illegal task chain table by the DMA controller to attack the condition access chip, thereby improving the safety performance of the condition access of the digital television.