New Roughtime IETF draft

[Marcus Dansarie]

A new Roughtime IETF draft has been posted: https://datatracker.ietf.org/doc/html/draft-ietf-ntp-roughtime. It makes a number of changes following feedback from the IETF NTP working group. Unfortunately, it also introduces a number of changes that break compatibility with the previous draft:

* The context string to generate the signature over the DELE value has been changed to remove the two trailing dashes. This change is for consistency with the other context string.

* Truncated SHA-512 has been replaced with SHA-512/256.

Other changes include:

* Clarification that all timestamps refer to UTC.

* Zero-length LEAP tags are no longer allowed. Servers indicate that they do not have leap second information by omitting the LEAP tag, like with DUT1 and DTAI.

* The unit of DTAI (the difference between TAI and UTC) is now in whole seconds, since that value is specified as an integer by the ITU.

* All other time values are now in microseconds for consistency.

* Improved description of the root value calculation algorithm, including pseudocode.

* Emphasized that clients must check that the received nonce in the response is the same as the one sent in the request.

* Updated list of Roughtime servers.

* Added reserved range of tags for private or experimental use.

* Added recommendations on the use of nonces generated from user-provided data.

* Removed references to JSON.

* Updated TCP reference from RFC 793 to RFC 9293.

My server and client implementations at https://github.com/dansarie/roughtimed and https://github.com/dansarie/pyroughtime have been updated. The server running on roughtime.se has also been updated, for anyone wishing to do interoperability testing.

Kind regards,

Marcus