A Digital Standard Time Dissemination Architecture for Trustworthy Time Stamping

In this paper, a reliable and accurate two-layer standard time dissemination architecture is proposed to implement direct digital time traceability. First, the system uses a clock calibration procedure based on two-way time transfer over a general dialup telephone modem and achieves a couple of milliseconds of accuracy. Second, a delegation time stamping mechanism is implemented with a forward-secure proxy signature scheme to provide digital time stamps with enhanced validity assurance and with digital time traceability to the national standard. The Request for Comments 3161 time stamp token is then extended to embed the standard time reading and necessary verification certificates. These features allow users to remove the blind trust on a commercial time stamping authority´s clock handling procedure.