[Emu] EAP TLS 1.3 backward compatibility with RFC 5216

[Bernard Aboba <[e-mail]>]

draft-ietf-emu-eap-tls13-16 Section 2.1 contains the following text:

   EAP-TLS 1.3 remains backwards compatible with EAP-TLS 1.2 [RFC5216]
. TLS version
   negotiation is handled by the TLS layer, and thus outside of the
   scope of EAP-TLS.  Therefore so long as the underlying TLS
   implementation correctly implements TLS version negotiation, EAP-TLS
   will automatically leverage that capability.


I am concerned that this statement is potentially misleading. An
implementation of RFC 5216 that negotiates TLS 1.2 and utilizes the key
hierarchy defined in RFC 5216 Section 2.3 will not interoperate with an
implementation of draft-ietf-emu-tls13-16 that also negotiates TLS 1.2 and
utilizes the key hierarchy defined in Section 2.3 of that document.

So in what sense is EAP-TLS 1.3 "backwards compatible" with EAP-TLS 1.2?

The only way this makes sense to me is if it is stated that
draft-ietf-emu-eap-tls13 applies only when TLS 1.3 is negotiated, and that
if TLS 1.2, 1.1 or 1.0 is negotiated, then RFC 5216 applies.