[TLS] RFC8446 backward compatibility question

Toerless Eckert <tte@cs.fau.de> Thu, 05 August 2021 20:44 UTC

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Date: Thu, 5 Aug 2021 22:43:55 +0200
From: Toerless Eckert <tte@cs.fau.de>
To: tls@ietf.org
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Subject: [TLS] RFC8446 backward compatibility question
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I am trying to figure out if every implementation compliant with
RFC8446 is also necessarily interoperable with an RFC5246 peer, or if this
is just a likely common, but still completely optional implementation choice.

I could not find any explicit statement that backward compatibility
with RFC5246 is mandatory (but i just was doing browsing/keyword search
over RFC8446). COnditional text such as:

"implementations which support both TLS 1.3 and earlier versions SHOULD"

make me think that TLS 1.2 backward compatibility is just optional.