Re: [netconf] Paul Wouters' Discuss on draft-ietf-netconf-over-tls13-03: (with DISCUSS and COMMENT)

[Rob Sayre <[e-mail]>]

Sean Turner <[e-mail]> wrote:
> For TLS 1.2:
>
> RFC 7589 includes the following text:
>
> Implementations MUST support TLS 1.2 and are REQUIRED to
>  support the mandatory-to-implement cipher suite.
>
> That cipher suite is TLS_RSA_WITH_AES_128_CBC_SHA.

I think the text could be clearer still, because the draft cites RFC 9325
as a normative reference.

There, we can find this text:

"The previous version of the TLS recommendations [RFC7525] implicitly
allowed the old RFC 5246 mandatory-to-implement cipher suite,
TLS_RSA_WITH_AES_128_CBC_SHA. At the time of writing, this cipher suite
does not provide additional interoperability, except with very old clients.
As with other cipher suites that do not provide forward secrecy,
implementations SHOULD NOT support this cipher suite. Other application
protocols specify other cipher suites as mandatory to implement (MTI)."

<https://www.rfc-editor.org/rfc/rfc9325.html#name-implementation-details>

So, do implementations have to support TLS_RSA_WITH_AES_128_CBC_SHA, even
if they have some better options?

thanks,
Rob