The present invention relates to serial cipher technology in enciphering and cipher, and has the main content of creating and buffer storing cipher sequence for serial enciphering process in advance. The technological points include: using one cipher key buffer memory for storing cipher key sequence; creating cipher sequence in advance and storing in the cipher key buffer memory; and responding the enciphering request to encipher data through obtaining complete or partial cipher key sequence from the cipher key buffer memory. In this way, the job of data enciphering with serial cipher is dispersed in the whole system operation period and the enciphering is completed through simple XOR operation after enciphering request.