Re: [TLS] [Editorial Errata Reported] RFC6347 (4642)

worley@ariadne.com (Dale R. Worley) Tue, 22 March 2016 18:17 UTC

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From: worley@ariadne.com (Dale R. Worley)
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Cc: sean+ietf@sn3rd.com, rfc-editor@rfc-editor.org, Kathleen.Moriarty.ietf@gmail.com, tls@ietf.org, nagendra@cs.stanford.edu
Subject: Re: [TLS] [Editorial Errata Reported] RFC6347 (4642)
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<grubba@gmail.com>; writes:
> As far as I can see, the original text is correct, which is easy to
> see if you look at the corresponding paragraph of RFC 4347 (DTLS 1.0):
>
>     version
>       The version of the protocol being employed. This document
>       describes DTLS Version 1.0, which uses the version { 254, 255 }.
>       The version value of 254.255 is the 1's complement of DTLS
>       Version 1.0.
>
> If the suggested text had been correct, then the encoding in RFC 4347
> would have been { 254, 254 } as DTLS 1.0 is based on TLS 1.1.

You're right, { 254, 255 } is the complement of { 1, 0 }, so the erratum
must be incorrect.

Oddly, the following sentence in RFC 4347 is factually incorrect as an
architectural statement but is correct as a description of the protocol:
"This maximal spacing between TLS and DTLS version numbers ensures ..."
The Hamming spacing isn't maximal, that would be obtained with { 254,
254 }, but it is the value that is used and it does ensure that the
protocols are easily distinguished.

Dale