Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-for-ntp-18.txt
Hal Murray <hmurray@megapathdsl.net> Mon, 22 April 2019 08:06 UTC
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From: Hal Murray <hmurray@megapathdsl.net>
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Date: Mon, 22 Apr 2019 01:06:20 -0700
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Subject: Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-for-ntp-18.txt
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Typo, page 20: Duplicate "Nonetheless, " Page 6, single round trip That's after the TLS setup. Right? How many round trips does that take? Page 13: cookies Do all cookies have to have the same length? Page 17, Nonce length and Nonce in general. I don't understand this area. (My version of "understand" is that I could explain it to somebody.) It seems really really ugly to have an Additional Padding field that requires a layer of magic to compute the length. Am I missing something simple? If I poke around in AEAD RFCs, I find text about having a counter to make sure the nonce is unique. Is that appropriate or necessary? It's really really hard to keep from reusing a counter if you consider disks getting restored from backup and such. Are random number generators good enough? How do I figure out how many bits I need? How nonce-reuse resistant are the algorithms we are using? Why not require the client to use the same length as the server? Maybe pad the client nonce with 0s if generating randomness is expensive and it doesn't need as long a nonce as the server. Did anybody test this? (I doubt if our code will do the right thing.) Should we include a table of AEAD algorithms and the Nonce size? Page 19: Why MUST the Unique Identifier be in the clear? Page 21: What is an AEAD tag? I couldn't find any other references. Page 23: KoD/NTSN They can be forged. What's the current policy on processing KoDs? Page 23, last paragraph, save AEAD alg, S2C, C2S, and cookie to avoid NTS-KE on NTP restart. I think that paragraph would be better in an appendix. In addition to avoiding the load on the NTS-KE server, it also avoids the time delay that would add to the startup sequence. Page 24: "AEAD key" AEAD is used in two contexts - one for the wire and another for cookies. It would be nice if that word wasn't reused here. I don't have any good wordsmith suggestions. Page 36, checking certificates before you know the time. Does the NTP_PHASE_MAX test work with systems that have been sleeping in low power mode? "by picking a random time in the week preceding"... At a quick read, it's not obvious if that's an example of what to do or what not to do. Is the idea that the certificate will get updated at least a week in advance, so asking a week in advance will get the new certificate? Page 37/42, [Shpiner] The reference on page 42 says "Mizraha, T" - no mention of Shpiner. -- These are my opinions. I hate spam.
- [Ntp] I-D Action: draft-ietf-ntp-using-nts-for-nt… internet-drafts
- Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-fo… Hal Murray
- Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-fo… Marcus Dansarie
- Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-fo… Watson Ladd
- Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-fo… Marcus Dansarie
- Re: [Ntp] I-D Action: draft-ietf-ntp-using-nts-fo… Watson Ladd