[TLS] Re: Review of draft-santesson-tls-gssapi-00

[Simon Josefsson <simon at josefsson.org>]

<Pasi.Eronen at nokia.com> writes:

> Ari Medvinsky wrote:
>> 
>> Pasi,
>> 
>> I have two objections to the proposal of doing a GSS exchange 
>> after the finished msgs:
>> 1) Numerous existing applications expect to know the identity of the
>> client upon completion of the handshake (e.g., consider https for
>> existing web servers, there lots of other examples); your proposal
>> would require major overhaul to the way apps are secured today with
>> TLS
>
> I'm not sure if I understand this concern. Certainly a TLS library
> doing GSS-API would tell the application "handshake completed"
> only after the GSS-API part was also completed?

I'm not convinced of that.  It is useful for TLS library APIs to be
consistent with the TLS protocol.  Your proposal was to add the
GSS-API negotiation after the TLS handshake.

What this means in practice is that, to speak in library-specific API
terms, that applications after calling gnutls_handshake() will have to
call gnutls_gssapi_handshake().  This is similar to what we did for
TLS/IA, after gnutls_handshake() the application calls
gnutls_ia_handshake() to perform the inner handshake.  Only once both
calls have finished successfully will the application be satisfied.

I disagree that this is a serious problem.  Yes, both TLS libraries
and applications must be changed, but they need to be changed to
support this functionality anyway.  The changes inherent in Pasi's
proposal aren't that much bigger than those in Stefan's original
proposal.

/Simon

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