| 摘要 |
PROBLEM TO BE SOLVED: To suppress illegal action by registering certifiers obtained for respective document data and obtaining the next certifier from previous document data. SOLUTION: The input data D1 of the time T1 are cipher-processed by a data encryption standard(DES) and turned to output C1. An exclusive OR gate(EOR) exclusively ORs the C1 and data D2 inputted at the time T2 and inputs a result to the DES again. The output is exclusively ORed with the data D3 inputted at the time T3 as C2, processed in the DES and turned to the output C3. In such a manner, Dn inputted at the final time Tn and Cn-1 fed back at the time Tn-1 are exclusively ORed, the high-order 32 bits of the output Cn are taken out and the certifier is obtained. The certifier is stored in a magneto-optical disk for respective documents along with obtained time information. Also, the certifier is stored in a certifier storage memory inside a module and a cumulative certifier is generated. |
