Yo Richard! On Fri, 18 Jan 2019 16:28:56 -0600 Richard Laager via devel <devel@ntpsec.org> wrote:
> > Thanks, that seems to prove my point. The S2C and C2S are > > 'extracted' not 'dependent'. > > RFC 5705 starts, "A number of protocols wish to leverage Transport > Layer Security (TLS) [RFC5246] or Datagram TLS (DTLS) [RFC4347] to > perform key establishment but then use some of the keying material > for their own purposes." "wish" is not MUST. Just because we use Transport Layer Security (TLS) [RFC5246] to send the cookie(s) does not mean it is intertwined with the cookie contents. > Unless I'm misunderstanding, that is exactly what is going on here... We at least fail in a common understanding of what is not yet going on here. > NTS-KE uses TLS. Then the TLS session is used to provide keys to > NTS-KE for ultimate use in NTP. I think we are confusing different session keys. There are the session keys created for the current TLS session. They are, potentially, unrelated to the session keys in the NTS cookie. > Hal's original statement was, "You can't precompute cookies. They > contain S2C and C2S which depend on the TLS sesson key." And I still disagree. > While there is technically nothing called a TLS session key in the TLS > standard, the use of "session key" in this context is quite common. Yes, and that session key is not the C2S or S2C session key. > I understand Hal's point to be: S2C and C2S depend on the TLS > session's master secret, etc., and thus require the TLS session to be > fully established. I also understand that to be Hal's point. And I still believe that is an over-reading of the RFCs. Maybe we want to derive C2S and S2C from the TLS session, but I do not see that as mandated. > Therefore, you cannot compute cookies prior to a > particular TLS session being established. And I disagree with that. Not to be mistaken for me wanting them to be precomputed. RGDS GARY --------------------------------------------------------------------------- Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703 g...@rellim.com Tel:+1 541 382 8588 Veritas liberabit vos. -- Quid est veritas? "If you can’t measure it, you can’t improve it." - Lord Kelvin
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