TIME STAMP SYSTEM, TIME STAMP REQUESTING DEVICE, TIME STAMP VERIFYING DEVICE, AND COMPUTER PROGRAM

摘要

PPROBLEM TO BE SOLVED: To prevent an illegal later time stamp from being given by a 3rd person to digital data. PSOLUTION: A terminal device (time stamp requesting device) 1 of a user requests a time stamp device 2 to provide a time stamp of a digital document whose assumed maximum time stamp request frequency is (n). At this time, when the request frequency of the time stamp is (j), time stamp request data obtained by converting a combination of commit information having a value obtained by recursively converting an initial value up to (n-j+1) times by a hash function and the digital document by using the hash function. The time stamp device 2 generates and sends back a time stamp token for revised digital data based upon the time stamp request data received from the terminal device 1. PCOPYRIGHT: (C)2005,JPO&NCIPI