NTPsec is potentially dangerous: hostile forking and temperamental leadership
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Both of the projects also generally required knowledgeable people as they're in specialist areas.
Like any implementation of NTP, NTPsec needs to work at the protocol level, but I don't know whether it was practical for the NTP project to accept the degree of change in it's codebase that the NTPsec people wanted. In an ideal world the fork could have been avoided and a more vibrant community of developers would have happened.