the input iv register b 2 is selected at the selector circuit b 6 and input the selected data to the common key cipher core des aes b 8 the input data to the output data buffer b 12 is selected by the selector circuit b 11 either of the output of the common key cipher core des aes b 8 the output obtained by an exclusive or operation of the output of the common key cipher core des aes b 8 and the input data buffer b 1 or the output obtained by an exclusive or operation of the output of the common key cipher core des aes b 8 and the input iv register b 2 is selected at the selector circuit b 11 and input the selected data to the output data buffer b 12 the input data to the output iv register b 3 is selected by the selector circuit b 4 either of the output of the input data buffer b 1 the output of the selector circuit b 11 or the output of the increment circuit b 7 for incrementing the input iv register b 2 by 1 is selected at the selector circuit b 4 and input the selected data to the output iv register b 3 fig4 is a diagram of a data path in the case of the ecb mode encryption decryption in the block diagram of fig3 a data path selected is indicated by a solid line in fig4 in the block structure shown in the block diagram of fig3 when ecb mode encryption or ecb mode decryption is instructed by the dna descriptor the ecb mode is a mode not using.