| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a portable terminal for eliminating re-evaluation of design of an enciphering circuit even if a clock frequency of CPU is shifted, and reducing power consumption. <P>SOLUTION: A communication control circuit 100 includes a transmission function for transmitting transmission data to outside, and a receive function for receiving data from outside. The communication control circuit 100 determines whether the received data is enciphered, and the date is transferred to the CPU 1 if it is not enciphered, and the data is transferred to a decoding circuit 300 if it is enciphered. When the data is transmitted to outside by the communication control circuit 100, an enciphering circuit 200 enciphers the data if the encryption is necessary. When the outer data is received by the communication control circuit 100, the decoding circuit 300 decodes the received data if the decoding is necessary. The enciphering circuit 200 and the decoding circuit 300 are constituted by an asynchronous circuit made up of two-line system logics. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
