Depends on how synchronized you need to be. In the context of running airgapped:
A rubidium oscillator or Chip Scale Atomic Clock is in the price range you quote. However, these can drift enough that you should occasionally synchronize with a reference time source. This is to ensure continued millisecond accuracy. Of course it all depends on how much drift you'll tolerate, and if you're OK with being within a second, then a rubidium might be ok. Caesium oscillators which have much lower drift are in the $30K-50K range. These would require significantly less frequent synchronization, but are definitely not a few thousand dollars. Note that these are both just oscillators and they need additional support hardware to be able to be queried by NTP. Or stated differently, they still need a NTP server. Yes, there are products out there which integrate everything in one box at an additional cost. On Mon, Aug 7, 2023, 11:02 PM Masataka Ohta < mo...@necom830.hpcl.titech.ac.jp> wrote: > Forrest Christian (List Account) wrote: > > > In the middle tends to be a more moderate solution which involves a mix > of > > time transmission methods from a variety of geographically and/or network > > diverse sources. Taking time from the public trusted ntp servers and > > adding lower cost GPS receivers at diverse points in your network seems > > like a good compromise in the middle. That way, only coordinated > attacks > > will be successful. > > Instead, just rely on atomic clocks operated by you. They are not > so expensive (several thousand dollars) and should be accurate > enough without adjustment for hundreds of years. There can be no > coordinated attacks. They may be remotely accessed through > secured NTP. > > Masataka Ohta >
