METHOD OF MAINTAINING SOFTWARE INTEGRITY

摘要

A method of maintaining the integrity of software stored in memory, the method comprising: storing an indicator associated with the memory; calculating a reference value from the stored indicator; storing the reference value; modifying the indicator when the software in the memory is modified; storing the modified indicator; recalculating the reference value from the modified indicator; storing the recalculated reference value; and verifying the integrity of the software by: retrieving the modified indicator; calculating an expected value from the modified indicator; and comparing the expected value with the recalculated reference value. Preferably the integrity of the software is verified without calculating an expected value from the software. The reference and expected values are typically calculated in accordance with a secret key.