Patent ID: 7734598

Claim:
A computer-readable recording medium having recorded a hash-value generation program for generating a hash value of data stored on a target disk by the use of a one-way hash function, the program, when executed by a computer, causes the computer to perform a method, the method comprising: dividing the target disk into fixed-length segments; calculating per-segment hash values by applying the one-way hash function to data in every segment generated by the dividing; arranging the per-segment hash values in a same order as the segments are arranged; calculating a total hash value by applying the one-way hash function to the arranged per-segment hash values; saving the calculated total hash value calculated at a specified time; repeating the calculation of the per-segment hash values and the calculation of the total hash value to obtain a recalculated total hash value at a later time; and comparing the calculated total hash value with the recalculated total hash value to verify the calculated total hash value and the recalculated total hash value match.