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

Viktor Dukhovni <ietf-dane@dukhovni.org> Sun, 17 November 2019 00:22 UTC

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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [TLS] WGLC for draft-ietf-tls-ticketrequests
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On Sat, Nov 16, 2019 at 03:59:53PM -0800, Benjamin Kaduk wrote:

> > That also works, effectively treat 0xff as "-1", but all other
> > values as non-negative, with 0 a request for re-use.  An isomorphic
> > encoding, but without the "-1".
> 
> [Jeremy had a more eloquent description of the vague sketch of an idea that I had in my head]

Jeremy's "isomorphic" encoding works fine for me, and is likely less confusing.
So, FWIW, it has my support.  Fleshing it out a bit more, I am proposing:

    - 0xff => send no tickets

    - 0x00 => reuse requested:
        + send no tickets if presented ticket is accepted and reusable
        + send one ticket if presented ticket is accepted, but is not reusable
          (expired, or reuse is not allowed).
        + Also send one ticket if session could not be resumed and a full
          handshake was performed.  Clients that reuse tickets don't need a
          separate one for each session, so one per full handshake should
          suffice.

    - 0x01-0xfe => client wants single-use tickets:
        + send up to that many tickets on full handshake,
        + however, generally send just 1 ticket on resumption, or when
          replacing tickets during long-lived connections.  This helps to
          reduce chronic ticket "oversupply".

-- 
    Viktor.