TIME STAMP ADDING DEVICE, TIME STAMP ADDING METHOD AND COMPUTER PROGRAM

摘要

PROBLEM TO BE SOLVED: To provide a time stamp adding device capable of adding a highly reliable time stamp while ensuring the originality of an electronic mail text. SOLUTION: This time stamp adding device 3 is provided with an electronic signature adding section 301 for forming electronic signature data of a predetermined format and adding the formed signature to the electronic mail if the electronic mail to be sent has no electronic signature; a hash value generating section 302 for extracting a signature value from the electronic signature data and generating a hash value of the signature value using a predetermined hash function; a time stamp requesting section 303 for transmitting a time stamp requesting message having the hash value stored therein to a server operated by a time authenticating provider; a response message checking section 304 for checking the contents of a response message from the server; and a time stamp adding section 305 for adding the time stamp information stored in the response message to a non-signature attribute region of the electronic signature data. COPYRIGHT: (C)2008,JPO&INPIT