| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a semiconductor memory device with enhanced security function for memory data. <P>SOLUTION: The semiconductor memory device provided with a memory storing data and a data scramble circuit encrypting data to be stored according to a key code for data scramble and outputting it from the memory, includes: the memory having a first storing part storing the key code for data scramble to be sequentially updated; a pseudo random number generating circuit generating pseudo random number corresponding to the first key code for data scramble extracted from the first storing part and supplying the generated pseudo random number to a data scramble circuit as a second key code for data scramble; and an arithmetic operation circuit arithmetically operating the first key code for data scramble extracted from the first storing part and the second key code for data scramble to prepare a third key code for data scramble, and updating the first key code for data scramble to the third key code for data scramble by writing the prepared third key code for data scramble in the first storing part. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
