Re: [TLS] 0-RTT encrypted data limits

Eric Rescorla <ekr@rtfm.com> Thu, 01 September 2016 15:35 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Thu, 1 Sep 2016 08:25:11 -0700
Message-ID: <CABcZeBM3sk9ROXnnYNdOtcD5T7U68bSBeEbaUzroRUoNOykqrQ@mail.gmail.com>
To: Ilari Liusvaara <ilariliusvaara@welho.com>
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Subject: Re: [TLS] 0-RTT encrypted data limits
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On Thu, Sep 1, 2016 at 8:22 AM, Ilari Liusvaara <ilariliusvaara@welho.com>
wrote:

> On Thu, Sep 01, 2016 at 02:29:00PM +0000, David Benjamin wrote:
> > On Thu, Sep 1, 2016 at 10:01 AM Eric Rescorla <ekr@rtfm.com> wrote:
> >
> > > On Thu, Sep 1, 2016 at 6:15 AM, Ilari Liusvaara <
> ilariliusvaara@welho.com>
> > >>
> > >> Should there be recommendation for clients to cut transfer and send
> > >> Finished if the client receives EncryptedExtensions without
> > >> early_data extension?
> > >>
> > >
> > > I thought that was implicit, but i'd take a PR that did that.
> > >
> >
> > (s/EncryptedExtensions/ServerHello/, but whatever.)
>
> According to the table it is EncryptedExtensions (but there have been
> errors in it before)...
>

It goes in EE, because it should be encrypted.


> At this point the client must do much more than cut transfer anyway. It
> > probably should be phrased as starting over and retrying or so.
> Everything
> > sent has been rejected and all you thought you knew about the connection
> > may have changed, like ALPN. At sufficiently high layers, you should
> > probably just pretend you got a fresh connection and are repeating the
> > request (or whatever) from scratch.
>
> So server is supposed to continue on 0-RTT fail, but not client?


There are plenty of scenarios where the client can continue. For instance,
if the server has forgotten the ticket but is otherwise unchanged.

-Ekr


>
> -Ilari
>