As best as I can understand things, it's not possible to get started with authentication using current technology without already knowing the time. You don't have to know it very accurately, but it can't be wildly off or you are opening a crack for MITM attacks.
For example, page 18, section 9.3 of draft-ietf-ntp-network-time-security-13 says: "To solve this chicken-egg problem, the client has to rely on external means." If we are serious about security, the problem with getting started needs to be acknowledged prominently and frequently rather than buried in a paragraph that most implementers will skim over. That holds for both the NTS document and all documents that reference it. Is getting started complicated enough that we should put the discussion in another document? Has anybody thought about how close you need to know the time when getting started? A variation on this problem is that DNSSEC requries time, so you can't use DNS to locate time servers until you know the time. Again, you don't have to know it precisely, just close enough. Page 16, section 8.2 of draft-ietf-ntp-using-nts-for-ntp-04 says: "Therefore, NTS is unable to provide secure usage of NTP pools." I think that's misleading. It doesn't include the non-pool usage of DNS and you can use a pool after you know the time if the pool (and your API) supports DNSSEC. Is there an API to require the use of DNSSEC when doing DNS lookups? A well managed /etc/hosts (or equivalent) might be good enough, but the "well managed" part seems to be asking for trouble. -- These are my opinions. I hate spam. _______________________________________________ TICTOC mailing list [email protected] https://www.ietf.org/mailman/listinfo/tictoc
