Hi,

I think it is important to point out that the discussion has been about 
_protected_ result indications. RFC 3748 discussed protected and non-protected 
result indications. Also worth noting that it is not possible with protected 
failure indication when the server does not accept the ClientHello.

Michael Richardson wrote:
>is this really 3.5 round trips -> 4.5 round trips, or is it really more like 
>that we are >going from perhaps 5.5 round trips to 6.5 round trips (for 
>example).

For a full handshake it is probably more like 10.5 -> 11.5 roundtrips or more. 
Certificate chains are large and EAP-TLS typically sends 2 of them.

For resumption is might 3.5 round trips -> 4.5.

In cases a no-more-handshake indication is needed anyway to ease 
implementation, or in cases where the server wants client finished before 
sending newsessionticket, there is probably no increase at all.

John

-----Original Message-----
From: Emu <[email protected]> on behalf of Michael Richardson 
<[email protected]>
Date: Sunday, 7 February 2021 at 03:21
To: EMU WG <[email protected]>
Subject: Re: [Emu] Consensus call for result indicators in EAP-TLS 1.3


Joseph Salowey <[email protected]> wrote:
    > There is growing support for mandating result indicators for EAP-TLS
    > 1.3.  The result indicators help protect the EAP protocol exchange in
    > the many different types of environments EAP-TLS is used and make the
    > integration with the EAP state machine clearer.  This has the impact of
    > adding a round trip to EAP-TLS 1.3 making a total of 4.5 round trips.
    > It may be possible to optimize this exchange, but that would need
    > further study and would be beyond the scope of this effort.

    > This consensus call has two parts:

    > 1. Please respond to the list if you support adding explicit result
    > indications of success and failure from the EAP Server to the EAP Peer
    > in EAP-TLS 1.3.  If you object please respond to the list indicating
    > why.

I support this.

    > 2. Please respond to the list if you support using TLS close_notify
    > alert for a success indication and TLS error alert for a failure
    > indication.  If you object please respond to the list indicating why.

As I understand it, it is the use of Close_Notify that pushes us to 4.5 round
trips.

Given a client-certificate (or chain) of >1500 bytes more than one packet would 
be
required send that, and I believe that we can't send Close_Notify until the
certificate has been communicated (and verified).

So my question is: is this really 3.5 round trips -> 4.5 round trips, or is
it really more like that we are going from perhaps 5.5 round trips to 6.5
round trips (for example).
I posit this, because I think that the increase in round trip count is
largely irrelevant on non-challenged (RFC7228 term) networks.

--
Michael Richardson <[email protected]>   . o O ( IPv6 IøT consulting )
           Sandelman Software Works Inc, Ottawa and Worldwide





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