Patent ID: 7249258
Filing Date: 2007-07-24
Classification: G06Q,H04L

Abstract:
1. An original assurance method for assuring validity of original data using a plurality of first signature servers and a second signature server supervising said plurality of first signature servers, said method comprising: generating signatures for assuring validity of the original data; and performing verification of validity of the original data; wherein in the step of generating signatures for assuring validity, each of said plurality of first signature servers performs: a first log list registration step, when the first signature server receives digital data, of generating a digital signature for concatenation of said digital data and a first chain signature registered in a first log list, and adding said generated digital signature to said first log list; a first receipt transmission step of sending a first receipt including said first chain signature to a sender of the digital data; and a second receipt reception step of sending the first chain signature in said first log list to said second signature server, receiving a second receipt to the first chain signature from said second signature server, and storing said second receipt; and wherein in the step of generating signatures for assuring validity, said second signature server performs: a second log list registration step, when the second signature server receives a first chain signature from one of said plurality of first signature servers, of generating a digital signature for a concatenation of the first chain signature and a second chain signature registered in a second log list, and adding the generated digital signature to said second log list; a second receipt transmission step of sending a second receipt including said second chain signature to said one of said plurality of first signature servers; and a transmission management step of sending a second chain signature in said second log list to an external server; wherein in the step of performing verification of validity of the original data, each of said plurality of first signature servers performs: a first log list verification step, when the first signature server receives a first receipt with respect to original data, as an object of verification, of verifying each of first chain signatures ranging from a first chain signature included in said first receipt to a first chain signature that has been sent to said second signature server; and a second receipt transmission step of sending a second receipt to said second signature server, wherein the second receipt is received from said second signature server by sending the first chain signature to said second signature server; and wherein in the step of performing verification of validity of the original data, said second signature server performs: a second log list verification step, when the second signature server receives the second receipt from said first signature server, of verifying each of second chain signatures ranging from a second chain signature included in said second receipt to a second chain signature sent to said external server.