Patent ID: 7620585
Filing Date: 2009-11-17
Classification: G06Q

Abstract:
1. An electronic contract system configured for making a contract concerning predetermined contractual terms between a first transacting party and a second transacting party through a network, the electronic contract system comprising a first information processor used by the first transacting party and a second information processor used by the second transacting party, comprising: the first information processor including: a first contractual terms storing unit programmed to store contractual terms data C including a character string of the contractual terms; a first identification data generating unit having an operational function based on a predetermined algorithm that obtains output data univocally fixed with respect to input data, so as to generate first contractual terms identifying data ID a contractual terms information transmitting unit programmed to transmit contractual terms information including the contractual terms data C to the second information processor through the network; the second information processor including: a second contractual terms storing unit programmed to store the contractual terms data C in the contractual terms information that has been transmitted; a second identification data generating unit programmed to generate second contractual terms identifying data ID a second transacting-party signature generating unit programmed to generate a digital signature Sig a formal contractual proposal information transmitting unit programmed to transmit formal contractual proposal information including the second contractual terms identifying data ID wherein the first information processor further includes: a first signature verifying unit programmed to verify consistency between the second contractual terms identifying data ID a first identification data verifying unit programmed to verify a coincidence between the first contractual terms identifying data ID a first transacting-party signature generating unit programmed to generate a digital signature Sig a formal contractual acceptance information transmitting unit programmed to transmit formal contractual acceptance information including the coinciding contractual terms identifying data ID and the digital signature Sig the second information processor further includes: a second signature verifying unit programmed to verify consistency between the coinciding contractual terms identifying data ID and the digital signature Sig a second identification data verifying unit programmed to verify a coincidence between the second contractual terms identifying data ID wherein the first identification data generating unit and the second identification data generating unit each have a function to generate contractual terms identifying data with respect to the contractual terms data C by use of a specific algorithm selected from among N kinds of algorithms (N is two or more), and the same algorithm is selected and used in the first identification data generating unit and the second identification data generating unit when an arithmetical operation is performed to generate contractual terms identifying data with respect to the same contractual terms data C, and wherein the second identification data generating unit has a function to select a specific algorithm from among the N kinds of algorithms, and the formal contractual proposal information transmitting unit has a function to transmit an algorithm specifying code including a specific algorithm selected by the second identification data generating unit while being included in formal contractual proposal information, and the first identification data generating unit has a function to select the specific algorithm based on the algorithm specifying code that has been transmitted.