Re: [TLS] Fwd: New Version Notification for draft-pettersen-tls-version-rollback-removal-00.txt

[[e-mail] (Martin Rex)]

If there is anything worth considering that it would be an
approach which has

   (a) the highest possible likelyhood to succees the TLS handshake
      -- which pretty much means extension-less ClientHello with
      ClientHello.ClientVersion either {3,0} or {3,1}

   (b) and simultaneously succeding that very same initial handshake
       with the highest common protocol version supported by both peers
       -- which pretty much means that the client must convey his highest
       supported version through a cipher suite value and that the
       updated server will ignore/override ClientHello.client_version
       when it detects the SCSV-based version negotiation.

This will on the very first handshake even when the client does not
cache information about the server's capabilities, and it will work
without incuring failed TLS handshakes--an approach that for some
software stacks would require each and every application to implement
a reconnect fallback.

-Martin