Re: [TLS] 0-RTT & resumption

Ilari Liusvaara <ilari.liusvaara@elisanet.fi> Sat, 08 August 2015 05:42 UTC

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Date: Sat, 8 Aug 2015 08:42:32 +0300
From: Ilari Liusvaara <ilari.liusvaara@elisanet.fi>
To: Eric Rescorla <ekr@rtfm.com>
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Subject: Re: [TLS] 0-RTT & resumption
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On Fri, Aug 07, 2015 at 02:50:14PM -0700, Eric Rescorla wrote:
> I've updated the PR based on feedback from Dave, Ilari, and Martin.
> 
> https://github.com/tlswg/tls13-spec/pull/211
> 
> I'll merge this PR on 8/11 unless there are serious objections. As usual
> please send minor changes as github comments and/or PRs.
 
Few small comments (I leave larger stuff out):

1)

"If indicate the same parameters as the server indicated in that connection."

I can't parse this.

2)

"Send the same cryptographic determining parameters (Section 
{{cryptographic-determining-parameters}}) with the previous connection"

What if client is resuming connection for the first time and is keying
0-RTT accordingly?

I presume that the ciphersuite used for 0-RTT is then the ciphersuite
from session being resumed but key exchange changed to PSK (e.g.
TLS_ECDHE_FOO_WITH_BAR -> TLS_PSK_WITH_BAR), as this is the ciphersuite
resumed session would use.

(Where is the rule on what ciphersuite resumed session uses stated?
I thought the ciphersuite always needed to have the same symmetric
part?)



-Ilari