Re: [TLS] Ticket request PR#20
Nick Harper <nharper@google.com> Mon, 20 April 2020 19:18 UTC
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From: Nick Harper <nharper@google.com>
Date: Mon, 20 Apr 2020 12:18:28 -0700
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Subject: Re: [TLS] Ticket request PR#20
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On Sun, Apr 19, 2020 at 4:06 PM Viktor Dukhovni <ietf-dane@dukhovni.org> wrote: > On Sun, Apr 19, 2020 at 03:41:49PM -0700, Eric Rescorla wrote: > > > I don't think we should make this change. In the context of this draft, > if > > the client wants that behavior, it should send {1, 1}. > > That precludes clients from soliciting 0 *only* from servers that > support some future specification, and otherwise getting 1 from > servers that support only the current specification. > That's not true. Suppose there's some future specification FOOBAR that a client and server might support, and the client wants a resumption_count of 0 when the server supports FOOBAR and 1 if the server doesn't support FOOBAR. The apparent problem is that the client doesn't know whether the server supports FOOBAR when it writes its resumption_count value. It's true that the client doesn't know whether the server supports FOOBAR on its first connection to the server, but on that connection, the value of resumption_count is irrelevant. On future connections, the client can condition resumption_count based on whether FOOBAR was supported on the connection that the resumption ticket came from. > > Such clients are not looking for a static server behaviour, but > rather need only certain servers to return 0, and the rest > to return 1. > > In any case, if sending 1 or more unconditionally was fine for RFC8446 > (e.g. per the text in C.4) it is hard to imagine why it is suddenly so > important to insist that the server be able to send 0 when receiving > {1, 0} or {0, 1}. > > Servers that don't support this new extension at all will send 1 (or > more). So it is clearly not a big deal also for servers that do > support it to do likewise. > > Since there is no specific *use-case* for {1, 0} to mean 0 at present, > that couldn't also be handled by sending {0, 0}, there is no reason > to stand in the way of defining {1, 0} to be a solicitation for at > least 1 ticket regardless of the handshake type. > > The only objection that makes sense is a blocking tactic to preclude > potential future refinement of this draft to support reuse, but surely > blocking that evolution can be deferred to the discussion of the > (misguided?) I-D that proposes it. > My take on this PR is that it unnecessarily complicates the ticketrequest draft. As currently specified, the two values do what they say on the tin; with this PR there's an extra weird edge case. This complication is unnecessary based on my above description of how the FOOBAR spec can extend it. > > -- > Viktor. > > _______________________________________________ > TLS mailing list > TLS@ietf.org > https://www.ietf.org/mailman/listinfo/tls >
- [TLS] Ticket request PR#20 Viktor Dukhovni
- Re: [TLS] Ticket request PR#20 Eric Rescorla
- Re: [TLS] Ticket request PR#20 Viktor Dukhovni
- Re: [TLS] Ticket request PR#20 Nick Harper
- Re: [TLS] Ticket request PR#20 Viktor Dukhovni
- Re: [TLS] Ticket request PR#20 Viktor Dukhovni
- Re: [TLS] Ticket request PR#20 Sean Turner
- Re: [TLS] Ticket request PR#20 Benjamin Kaduk
- Re: [TLS] Ticket request PR#20 Viktor Dukhovni
- Re: [TLS] Ticket request PR#20 Benjamin Kaduk
- Re: [TLS] Ticket request PR#20 Salz, Rich