Re: [TLS] What's the right version number in the PreMasterSecret

[Xuelei Fan <[e-mail]>]

On 8/10/2010 11:26 PM, Yngve N. Pettersen (Developer Opera Software ASA)
wrote:
> On Tue, 10 Aug 2010 16:57:09 +0200, Martin Rex <[e-mail]> wrote:
> 
>> Michael D'Errico wrote:
>>>
>>> Based on the scenarios below, it looks like Opera is doing the right
>>> thing during the renegotiation while IE 8 is not.
>>
>> Opera is sending the correct client_version in the RSA PreMaster Secret
>> in both handshakes (initial and renegotiation).  Handshakes in the
>> originial SSLv3 and TLS protocol were completely independent and
>> self-contained, so the back-reference of the client_version in
>> RSA premaster secret is ALWAYS to the ClientHello handshake message
>> of the current handshake.
>>
>> But both browsers should actually be sending their highest supported
>> protocol version as client_version on EVERY ClientHello handshake
>> message--independent of whether they propose session resumption--
>> and both browsers appear to flunk on this point.
> 
> I have not been able to locate the exact reason for our policy, but if
> we have an active session against a server we will use the negotiated
> protocol version in future handshakes.
Java (SunJSSE) use the same policy as Opera, use the negotiated protocol
version for renegotiation.

> 
> This policy is 11+ years old, and was probably implemented because there
> was some kind of problem with resuming sessions using a Hello protocol
> version different from the one we used when setting up the session.
> 
> It may be possible to remove this, along with all the version fallback
> code, when we enter strict Renego patch mode.
I'm a little worried about the interoperability. I'm not sure, but if
some vendors care about the protocol version in renegotiation
ClientHello, for example, comparing the ClientHello.client_version with
the cached negotiated protocol version.

Anyone know which TLS implementations do not use the negotiated protocol
version for abbreviated handshake?

Thanks,
Xuelei (Andrew) Fan