Re: [TLS] Working Group Last Call for draft-ietf-tls-downgrade-scsv-00

[Martin Thomson <[e-mail]>]

On 26 September 2014 05:00, Joseph Salowey (jsalowey)
<[e-mail]> wrote:
> This is an announcement for the working group last call for draft-ietf-tls-downgrade-scsv-00.  Please review the document and send your comments to the list by Friday, October 17, 2014.

I've implemented this specification, and it's available in Firefox
nightly builds.  I found no issues with implementing from the draft.
It's basically ready.

I have one very minor concern.

The exception in Section 4 implies that there is some interoperability
reason to avoid including the SCSV in a resumption request.  I think
that it would be better if the actual interoperability problem.  That
is, your original session was made to a server instance that only had
a lower version and is being resumed on an instance that has a higher
version AND the node with the higher version doesn't treat a resumed
handshake differently with respect to the handling of the SCSV.
Alternatively, the server could have been updated since the original
session was established.

After some consideration, I think that the only issue with resumption
is that it is somewhat wasteful.  Requiring servers to ignore the SCSV
on resumption would work equally well.

I have a few minor editorial nits:
  - the lists in Sections 3 & 4 have a single item, which is a little odd
  - Section 4 should just say when to use the SCSV, rather than
announce "This section specifies when to send it."