Abstract: Systems and methods for distributing trusted time, including trusted dates with digital data files, which are accessed, created, modified, received, or transmitted by devices that include a trusted time source in a tamperproof environment. The system includes one or more subsystems for providing trusted time for a moment in time. The trusted time source may be a real time clock, which is not resettable, is independent of any system clock of the devices, and where one or more devices may contribute to the distribution of trusted time among each other.

Abstract: A personal computer (PC) system and methods for proving dates of digital data files, which are accessed, created, modified, received, or transmitted by the PC includes a trusted time source in a tamperproof environment, a first subsystem for saving the file at a moment in time, a second subsystem for retrieving from the trusted time source a date and a time corresponding to the moment in time, a third subsystem for appending the date and the time retrieved from the trusted time source to the saved file, a fourth subsystem for signing the saved file with the date and the time retrieved from the trusted time source appended thereto, a fifth subsystem means for hashing the signed file to produce a digest, a sixth subsystem for signing the digest with a key to produce a certificate, a seventh subsystem for appending the certificate to the saved file, and an eighth subsystem for saving the file with the certificate appended thereto.