1. A method of preventing the repudiation of digitally-signed electronic documents, the method comprising the steps of: receiving a plurality of electronic documents during a first and second time interval; forming a message digest for each of the plurality of electronic documents; forming a first super-message digest derived at least in part from each of the message digests received during the first time interval; forming a second super-message digest derived at least in part from each of the message digests received during the second time interval and from the first super-message digest; transmitting the second super-message digest to a timestamp authority and receiving a timestamp therefrom; and recording each of the message digests, first and second super-message digests, and timestamp in an audit log.