Re: [TLS] WGLC for draft-ietf-tls-ticketrequests

"Martin Thomson" <mt@lowentropy.net> Tue, 21 January 2020 05:04 UTC

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Date: Tue, 21 Jan 2020 16:03:46 +1100
From: Martin Thomson <mt@lowentropy.net>
To: tls@ietf.org
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Subject: Re: [TLS] WGLC for draft-ietf-tls-ticketrequests
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On Thu, Nov 21, 2019, at 14:19, David Schinazi wrote:
> Regarding Viktor's suggestion, I personally believe it would increase the
> complexity of the proposal, and I don't see use-cases compelling enough
> to warrant that complexity. I would rather keep this proposal as simple as
> possible.

I see that I didn't respond to this.  I support David's view.

Even the suggestion that clients that resume only request one assumes that clients only want one.  The client probably knows better than we do.  I would rather say nothing about the number and keep it simple. 0 means 0, 1 means 1, N means N.

FWIW, the cost of oversupply is often marginal, depending on circumstances.  In a client-speaks-first protocol with no client certificate, the server can occupy the first round trip with tickets and generally gain a performance advantage (as sending more will increase the congestion window in most cases).  Otherwise, there are usually quiescent periods that can be exploited for sending tickets.  And tickets are small, and cheap to generate.  With one exception: if you are relying on client authentication and packing that into tickets, I'm sorry.