Subject: [Ntp] Roman Danyliw's No Objection on draft-ietf-ntp-using-nts-for-ntp-23: (with COMMENT)

From: Roman Danyliw via Datatracker <[email-masked]>
Date: Tue, 10 Mar 2020 20:03:00 -0700

Roman Danyliw has entered the following ballot position for
draft-ietf-ntp-using-nts-for-ntp-23: No Objection

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COMMENT:
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(tried to de-duplicate COMMENTs with Ben’s)

I support Ben Kaduk’s DISCUSS position.

** Section 3. Since NTS is a green field design, is there are reason to be
backward compatible to TLS version <1.3?

** Section 4.1.7.  Consider using RFC900 as a reference for IPv4 dotted decimal
notation.

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From: Hal Murray <[email-masked]>
Date: Wed, 11 Mar 2020 05:51:45 -0700

[I work on one of the implementations listed in Section 8]

Éric Vyncke  said:
> -- Section 3 -- I really wonder why TLS 1.3 is not a MUST (e.g., AFAIK TLS
> 1.3 is supported by openssl) but I will trust the security AD on this topic. 

> backward compatible to TLS version <1.3?

Short version:

Yes, a few older versions of OSes/distros are still shipping versions of 
OpenSSL that don't support TLS 1.3.

Long version:

Working code for NTS hit critical mass close to a year ago.  Back then several 
major OSes/distros were shipping an older version of OpenSSL that didn't 
support TLS 1.3.  Using TLS 1.2 was critical for getting off the ground.

A few months ago OpenSSL stopped supporting version 1.1.0 which didn't support 
TLS 1.3.  Most OSes/distros that were using it have updated to 1.1.1 which 
does support 1.3.  A few have not.

I won't complain much if that is changed to a MUST but I'd prefer not to.  The few older systems that don't support TLS 1.3 are probably happily running old stable code and unlikely to update to NTS.  On the other hand, NTS might make auditors happy.  Or there might be some other reason they want NTS.  I'd like to keep the option to support those older systems open.

There are currently a few words in Sections 4.2 and 5.1 that are relevant for using TLS 1.2.  I think we should leave them in to help somebody who wants to use NTS on one of those older systems.  OpenSSL hides those differences so they are probably not important for implementers.

Is there is a strong reason for dropping 1.2?  (I assume not or more systems would have updated to newer versions of OpenSSL a long time ago.)

-- 
These are my opinions.  I hate spam.