Re: [TLS] Non-browser clients.

[Dr Stephen Henson <[e-mail]>]

Nelson B Bolyard wrote:
> On 2009-11-21 05:24 PST, Dr Stephen Henson wrote:
> 
>> Just to add a point to this which hasn't really been mentioned.
>>
>> The discussion of connection logic has largely been browser centric,
>> non-browser clients often work in a different way and the current
>> proposal (draft-ietf-tls-renegotiation-01.txt) can cause them significant
>> problems.
> 
> Where is this draft?  It's not on rfc-editor.org nor on ietf.org.
> Are you referring to draft-RESCORLA-tls-renegotiation-01.txt?
> 

Yes I meant the 01 version at:
https://svn.resiprocate.org/rep/ietf-drafts/ekr/draft-rescorla-tls-renegotiate.txt

Fallbacks aren't explicitly mentioned in the 00 draft. The whole issue of how
one can support secure renegotiation (if the server supports it) but still
connect to an unpatched SSLv3 or unpatched extension intolerant TLS server isn't
covered.

The 01 draft resolves this issue but requires fallbacks.

It has been mentioned elsewhere that the obvious fallback techniques using the
00 draft are vulnerable to downgrade attacks. If anyone has a reference to a
fallback technique that isn't vulnerable and complies to the 00 draft I'd be
interested to hear it.

Steve.
-- 
Dr Stephen N. Henson.
Core developer of the   OpenSSL project: http://www.openssl.org/
Freelance consultant see: http://www.drh-consultancy.co.uk/
Email: [e-mail], PGP key: via homepage.