Patent ID: 7634653
Filing Date: 2009-12-15
Classification: G06Q,H04L

Abstract:
1. An event-ordering certification method for an event-ordering certification system having a user apparatus performing an event-ordering request for certifying a chronological sequence of a certain event in time-series events generating a designated digital information, a certification apparatus for drafting a certificate for the event-ordering request of the user apparatus, an audit apparatus for auditing authenticity of the certificate and a communication network for connecting the user apparatus, the certification apparatus and the audit apparatus with each other, the method comprising: an event-ordering request receiving step where the certification apparatus receives the event-ordering request from the user apparatus; a sequentially assigned data-item calculating step where the certification apparatus drafts a sequentially assigned data-item from the digital information included in the event-ordering request in accordance with a predetermined procedure; an event-ordering request aggregating step where, in sequential aggregation trees each of which is completed at regular time intervals by sequentially assigning a series of sequentially assigned data-items to leaves of a directed tree from left thereof, the certification apparatus calculates assigned values for calculable nodes and a root value to be assigned for a root of each sequential aggregation tree after completion of each regular time interval, in accordance with a calculating method of establishing, as an assigned value for a parent, a result value obtained by applying a designated collision-resistant hash function on a juncture value to which respective assigned values assigned to a plurality of nodes having a parent in common are connected; a certificate drafting step where the certification apparatus drafts a certificate containing the sequentially assigned data-item and a first sequential aggregation tree specifying information for specifying the sequential aggregation tree and a leaf thereof both having the sequentially assigned data-item assigned thereto; a certificate sending step where the certification apparatus sends the certificate to the user apparatus; assuming that: a leaf of the sequential aggregation tree to which the event-ordering request is assigned is defined as a registration point; an information about nodes necessary to calculate a root value of the sequential aggregation tree from the registration point is defined as a complementary information of the certificate; and in the complementary information, a complementary information acquirable at a point of assigning the event-ordering request to the sequential aggregation tree is defined as an immediate complementary information, an audit certificate drafting step where after assigning the event-ordering request to the sequential aggregation tree, the certification apparatus assigns a first audit request to the sequential aggregation tree thereby drafting a first audit certificate in the same way as drafting the certificate, acquires a first immediate complementary information for audit at the point of assigning the first audit request to the sequential aggregation tree, from the sequential aggregation tree and incorporates the first immediate complementary information into the first audit certificate; an audit certificate sending step where the certification apparatus sends the first audit certificate to the audit apparatus; a complementary information request receiving step where after assigning the first audit request to the sequential aggregation tree, the certification apparatus receives a request of the complementary information of the certificate from the user apparatus; a late complementary information drafting step where the certification apparatus acquires a second sequential aggregation tree specifying information for specifying the sequential aggregation tree and a leaf thereof both having the request of the complementary information assigned thereto and a complementary information acquirable at the point of assigning the request of the complementary information, from the sequential aggregation tree, thereby forming a late complementary information; and a late complementary information sending step where the certification apparatus sends the late complementary information about the certificate to the user apparatus.