Re: [hybi] On TLS-only Approaches

[Adam Barth <[e-mail]>]

On Sun, Aug 22, 2010 at 9:30 PM, John Tamplin <[e-mail]> wrote:
> On Mon, Aug 23, 2010 at 12:13 AM, Adam Barth <[e-mail]> wrote:
>> I should probably let EKR respond here, but I'll ask anyway.  What
>> does the message overhead look like for the null cipher spec?  We
>> don't necessarily need to use a non-null cipher spec for ws even if we
>> use a TLS handshake (of course, we need a reasonable cipher spec for
>> wss).
>
> It looks to me, according to openssl ciphers, the only NULL cipher supported
> is AECDH-NULL-SHA which still does SHA1 for integrity protection, so I
> assume it would have the same overhead.  RFC4346 seems to indicate a
> TLS_NULL_WITH_NULL_NULL CipherSuite option which would have a 0-byte MAC, so
> presumably you would only pay the 5-byte record overhead and there would be
> no padding.  That is more reasonable, but still seems large considering we
> have been arguing over a few bytes in the framing.

It's unclear to me whether those arguments have been reasonable, but
that's another discussion.  :)

I suppose another direction to explore is whether we can use the TLS
handshake and then drop the tunnel afterwards in the ws case.  Some of
our resident TLS experts might know.  I'd have to study the protocol
to see how that might work.

Adam