| 摘要 |
PROBLEM TO BE SOLVED: To oppose an attack for deciphering secret information by replacing and storing the secret information in a different place by electronic devices each time it is written to a volatile memory. SOLUTION: Data on the address 0000 of secret information before conversion in a memory 10 are D7hex and when the secret information is stored for the first time according to a storage converting rule, it is stored in address 0003 of the volatile memory 11 by conversion to F7hex. For second storage, it is stored in address 0003 of the volatile memory 11 by conversion to code data other than F7hex. Similarly, data on the address 0001 are 17hex, first storage in the address 0003 of the volatile memory 11 is performed by conversion to A2hex, and data on the address 0002 are 9Bhex; and first storage in address C123 of the volatile memory 11 is performed by conversion to 5Dhex. Thus, the secret information is stored in different places by electronic devices each time it is stored in the memory. |
