The TA’s time source is an atomic clock, which is synchronized with UTC (NICT) via GPS (Global Positioning System) common view technique. The role of TAs is to calibrate and audit clocks of time stamping servers of TSAs securely.
In this program, TSAs are required to derive trusted time from accredited TAs. The TSA generates a time-stamp token which contains a binding between the hash value and a time-value and then sends this token to the user. The user (subscriber or requester) generates the hash value for the data to be time-stamped and sends a time-stamp request message, which includes the hash value, to the TSA. The “time business” is a coined word and means TA and TSA services.įig.1 shows the framework of time-stamping services based on the accreditation program. The purpose of the program is to enhance trust levels of time-stamping services and to contribute to the technical infrastructure of IT societies. (ii) Accreditation is valid for 2 years and the accredited TA & TSA must submit an application to JADAC for the renewal. Requirements for applicants of the program are : (i) The accredited TA & TSA must have business footholds and facilities & equipments for time business within Japan. The criterions cover five fields, (i) technical issues, (ii) management and operation, (iii) facilities, (iv) network security and (v) disclosure and notification. The program is based on “The Guideline of Time Business” issued by MIC in November 2004, and is to approve if the services of a TA (Time Authority) and a TSA (Time Stamping Authority) meet the required criterions of the program. JADAC is a juridical foundation and its competent authority is the Ministry of Internal Affairs and Communications (MIC). 2.Accreditation Program (1) Overviewįebruary 2005, the Japan Data Communications Association (JADAC) established the voluntary accreditation program for time-stamping services. One of the major uses of time stamps is to time-stamp a digital signature to prove that the digital signature was created during the lifetime of its signing certificate. Applications of time stamps range from document management, patent protection, e-commerce to computer forensics and so on. Time stamps can prove that a digital file existed at a certain point of time and that its content has not been altered since that time. Electronic signatures and time stamps are fundamental technique to prove authenticity of electronic documents.
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