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Re: [TLS] Interaction between session resumption and negotiated protocol version

Dave Garrett <davemgarrett@gmail.com> Fri, 03 April 2015 23:33 UTC

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From: Dave Garrett <davemgarrett@gmail.com>
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Date: Fri, 03 Apr 2015 19:33:30 -0400
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Subject: Re: [TLS] Interaction between session resumption and negotiated protocol version
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On Friday, April 03, 2015 07:06:19 pm David Benjamin wrote:
> Conveniently, I spent a lot of time wrestling with this a while back and
> testing client implementations:
> https://github.com/tlswg/tls13-spec/issues/136

Just to note, the current draft still has an equivalent "SHOULD" in the
updated backwards compatibility section.

I dropped the "already knows" part, as that was not a particularly safe
assumption to keep. (both the "knowing" part & the fact that things
could of course change) The loose requirement for resumption is still in
there, just worded to be just for resumption.

TLS 1.2 has:

Whenever a client already knows the highest protocol version known to
a server (for example, when resuming a session), it SHOULD initiate
the connection in that native protocol.

TLS 1.3 currently has:

A client resuming a session SHOULD initiate the connection using the
version that was previously negotiated.


Dave

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