The below article provides another example of the importance of time and hence the need for multiple, independent, secure and resilient sources.

As a side note – one of RNTF’s biggest supporters first became interested in us because he was looking for an independent precise time source to pair with GPS for a critical nation-wide system. Yet every wide area time source he found, when he traced it back far enough, started with GPS. And he really didn’t want to buy hundreds of cesiums and scatter them about the country.

Researchers warn computer clocks can be easily scrambled

Network World
By Jeremy Kirk
IDG News Service | Oct 21, 2015

In 2012, two servers run by the U.S. Navy rolled back their clocks 12 years, deciding it was the year 2000.

The servers were very important: they’re part of a worldwide network that helps computers keep the right time using the Network Time Protocol (NTP).

Computers that checked in with the Navy’s servers and adjusted their clocks accordingly had a variety of problems with their phones systems, routers and authentication systems.

The incident underscored the serious problems that can occur when using NTP, one of the oldest Internet protocols published in 1985.

The protocol is fairly robust, but researchers from Boston University said on Wednesday they’ve found several flaws in NTP that could undermine encrypted communications and even jam up bitcoin transactions.

One of the problems they found is that it’s possible for an attacker to cause an organization’s servers to stopping checking the time altogether.

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