A data mask section outputs memory data read from a memory array unit for
a predetermined time period that is shifted from an edge timing of a
clock signal, while a microcomputer takes in the data output from the
data mask section at the edge timing of the clock signal. Thus, the
microcomputer is capable of appropriately taking in the memory data only
when the frequency of the clock signal is within a predetermined range,
and accordingly, it is difficult to fraudulently obtain the memory data.
Furthermore, the data mask section may output random data, or the like,
during a time period other than the predetermined time period. In such a
case, it is difficult to analyze the memory data, and the confidentiality
of the memory data is improved.