Patent ID: 7958367

Claim:
An authentication system comprising a document creation unit including a processor, a storage unit and a tamper-resistant device, a time distribution unit, and a document reception unit, the document creation unit, the time distribution unit and the document reception unit being coupled via a communication line, wherein the processor of the document creation unit calculates hash values of all software modules running in the document creation unit when the document creation unit is started, stores the hash values and information for identification of the hash values in the storage unit, and transmits the hash values to the tamper-resistant device to store the hash values in a storage area of the tamper-resistant device, wherein the processor stores time information increasing at regular intervals in the storage unit and, when an electronic document is created, additionally records the stored time information in the electronic document, wherein the processor receives latest time information from the time distribution unit, overwrites the stored time information with the latest time information and additionally records the latest time information in the electronic document, wherein the processor requests the tamper-resistant device to execute a digital signature immediately after additionally recording the latest time information in the electronic document, wherein the tamper-resistant device, in response to the request, combines the hash values stored in the storage area to create one piece of measurement auxiliary information, executes the digital signature with respect to information including the measurement auxiliary information using a key held in the device to obtain a digital signature value, and outputs the measurement auxiliary information, the digital signature value and a public key certificate corresponding to the key to the processor, and wherein the processor creates a measurement auxiliary document with the received measurement auxiliary information, digital signature value and latest time information.