DOCUMENT AGREEMENT SYSTEM, AGREEMENT DOCUMENT ISSUING DEVICE, COMMUNICATION TERMINAL, AGREEMENT DOCUMENT STORAGE DEVICE, AND AGREEMENT DOCUMENT STORAGE METHOD

PROBLEM TO BE SOLVED: To provide a document agreement system, agreement document issuing device, communication terminal, agreement document storage device, and agreement document storage method in which a document, that a plurality of persons agree with, can be stored safely at low costs. SOLUTION: An agreement document issuing device 121 issues an agreement document 151 by means of an issuing section 424, encrypts the agreement document 151 by means of an encryption/decryption device section 421 while using a private key 221 to create an agreement document 152, and transmits the agreement document 152 and a public key 322 to a client terminal 111. The client terminal 111 decrypts the agreement document 152 by means of an encryption/decryption device section 411 while using the public key 322 in order to allow a user to confirm contents of the agreement document 152, after user confirmation, encrypts the agreement document 152 while using a private key 211 to create an agreement document 153 and transmits the agreement document 153 to a certificate authority 131 by means of a communication section 413. The certificate authority 131 stores, in a data holding section 533, a set of the public key 323 of the agreement document issuing device 121, the public key 312 of the client terminal 111 and the agreement document 153. COPYRIGHT: (C)2010,JPO&INPIT