Re: applying AES-GCM to secure shell: proposed "tweak"

[der Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>    (There are some details left to specify on exactly how this should
>    interact with algorithm selection, since there are additional
>    dependencies.  You want to be able to ask for (aead, none) with a
>    fallback to (3des-cbc, hmac), without risk of ending up with
>    (3des-cbc, none).

I believe that's not directly possible at present, given the way
algorithm negotiation works.

However, it is fairly easy to offer enc=aead,3des-cbc mac=hmac, and, if
that negotiation succeeds, immediately re-kex with enc=aead mac=none.

>    Maybe it's easier to say that if an AEAD-algorithm is chosen for
>    encryption, the lists of mac algorithms (for that direction) are
>    ignored).

That would be a rather unpleasant violation of the existing definition.
I'd much rather just re-kex if using a none MAC is that important.

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