| 摘要 |
Tampering with fiscal information written to memory can be detected without reducing the write speed. When fiscal information is written to first memory unit 411 by means of a fiscal control CPU 42 , a memory control CPU 412 writes a first hash value corresponding to the fiscal information in second memory unit 413. When fiscal information is read from the first memory unit 411, the fiscal control CPU 42 reads the first hash value from the second memory unit 413 through the memory control CPU 412, compares the first hash value with a second hash value calculated from the fiscal information read from first memory unit 411, and detects tampering with the fiscal information.
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