摘要 |
When input data (f0) is read into a digital signature generating apparatus, a hash value (h0) is calculated. The hash value (h0) is stored to a storage area (M1), which has the highest priority rank among 5 storage areas. Subsequently, when input data (f1) is read in, a hash value (h1) is calculated. Since the storage area (M1) is already occupied by the hash value (h0), the hash value (h0) is read out from storage area (M1), emptying the storage area (M1). The read hash value (h0) and the hash value (h1) are concatenated, forming a concatenated hash value (h0|h1) and a hash value (h0,1) is calculated. The hash value (h0,1) is stored to a storage area (M2), which has the highest priority rank after the storage area (M1). When input data (f2) is read in, a hash value (h2) is calculated and stored to the storage area (M1). |