[Emu] Issue 59 - Key Update

[Joseph Salowey <[e-mail]>]

Please review the following proposal and discuss issues on this thread.

Alan's review pointed out the following

Section 2.1.1 says:
>    TLS 1.3 introduced the Post-Handshake KeyUpdate
>    message which is not useful and not expected in EAP-TLS.
> Q: What does it mean that the message is "not expected"?  This seems
> like a source of implementation-defined behavior, which experience
> shows has been a source of interoperability and security issues.


This does seem to require some more specification.  Here is a proposal.

"TLS 1.3 introduced the Post-Handshake KeyUpdate message which is not
useful and not expected in EAP-TLS.  Implementations SHOULD NOT send a
KeyUpdate message.  If a KeyUpdate message is received then an
implementation SHOULD ignore the message and it SHOULD NOT send a KeyUpdate
message in response."

I think this is better than "implementations MUST NOT send this message and
MUST fail upon reception".  The problem here is that the EAP TLS
implementation may not have control over this behavior.

Thanks,

Joe