RE: [TLS] Open issue: Record Version Numbers

[<Pasi.Eronen@xxxxxxxxx>]

Martin Rex wrote:

> However, the approach of the client using {3,1} in the record
> protocol will rightfully cause some SSLv3-only Server to abort the
> handshake, which amounts to a real interoperability problem, so
> clients ought to be strongly discouraged from taking that approach.

On the other hand, using {3,0} in the record protocol will cause 
some TLS 1.0 servers to abort the handshake (or fail it some way). 
Yngve's draft shows such servers do exist.

I don't think arguing which of them does it "rightfully" is very
useful (as Bodo pointed out, TLS 1.0 spec does not say that TLS
1.0-only servers should accept {3,0} in the record version);
we should be arguing about which approach will cause the least
amount of interop problems.

To this question, we don't seem to have a definitive answer yet.

> Changing a spec to break interoperability with perfectly correct
> (server) implementations (of SSLv3) is a pretty bad idea.

As basically all current TLS implementations send {3,1} in the 
record version (when configured to support both SSLv3 and TLS 1.0),
interoperability with servers that reject this is already broken
in real world.

Best regards,
Pasi

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