Re: [TLS] drop obsolete SSL 2 backwards compatibility from TLS 1.3 draft

[[e-mail] (Martin Rex)]

Dave Garrett wrote:
> Martin Rex wrote:
>> JDK 1.6 might be past its "End of Public Updates", but it is still
>> fully supported and pretty omnipresent, in particular in company
>> environments and the majority of server-side (J2EE) installations.
> 
> Server-side usage would not be affected by the proposed changes.

Server-side usage will be significantly adversely affected by a silly
MUST NOT accept TLSv1.2 offered in SSL Version 2.0 CLIENT-HELLO

>
> Server and client usage in company environments are where it is easiest
> to deal with the proposed changes. The clients' settings just need to be
> changed to stop using SSL entirely and send only v3 hellos.

The Server's setting will have to be changed to modify the client connections
originating from a J2EE server that is using Java 6.


> 
> I'll restate again, this is already the consensus.
> (again, assuming no surprises with the SSL3 I-D)
> 
> http://tools.ietf.org/html/rfc6176

You might be misreading that document:

  http://tools.ietf.org/html/rfc6176#section-3

   o  TLS servers MAY continue to accept ClientHello messages in the
      version 2 CLIENT-HELLO format as specified in RFC 5246 [TLS1.2],
      Appendix E.2.

A SSL Version 2.0 CLIENT-HELLO offering TLSv1.2 is perfectly sufficient
to negotiate the mandatory-to-implement TLSv1.2 TLS cipher suite:

  https://tools.ietf.org/html/rfc5246#section-9


>
> "TLS clients MUST NOT send the SSL version 2.0 compatible CLIENT-
> HELLO message format"

This applies only to *NEW* clients.  This does not affect the behaviour
of the installed base at all.  The Server-side needs to address the behaviour
of the installed base for the purpose of interop.


> 
> With both SSL2 & SSL3 prohibited, there should be no v2 hellos.

But there still are plenty of them around in the installed base.


> 
> Put bluntly, any environment that actually HAS v2 hellos is already
> ignoring IETF RFCs.

Behaviour of the installed base is well known to be unaffected by documents
published by the IETF (or any other organization, or government).


-Martin