[PATCH] DTLS: Add ECDHE-RSA-AES256-SHA384 as a v1.2 cipher suite

[Daniel Lenski]

On Fri, Jul 31, 2020 at 2:19 PM Nikos Mavrogiannopoulos
<n.mavrogiannopoulos at gmail.com> wrote:
>
> On Thu, Jul 30, 2020 at 10:00 PM Jason Gunthorpe <jgg at ziepe.ca> wrote:
> >
> > If GCM is not available on the VPN server this is a reasonable fallback.
> >
> > Severs will not auto-fallback to older TLS if the X-DTLS12-CipherSuite is
> > sent, so the existing non-GCM modes with the old TLS do not negotiate.
>
> In terms of security that's super ugly. All these CBC ciphersuites are
> problematic in TLS1.2 due to lucky13 attacks; TLS1.3 dropped all of
> them. It is simply too hard to make them secure and that's why they
> are disabled by default in openconnect. Not probably helpful solution,
> but you may want to refer your IT to good advise at:
> https://bettercrypto.org/

I believe that the only situation where this would actually *lower*
the security of a connection would be the case where a server supports
*both* GCM and CBC for DTLS 1.2 ciphers, but (for some insane reason)
chooses the CBC cipher when offered both options.

Do I have that right?

Dan