Re: [TLS] Proposed text for removing renegotiation

Eric Rescorla <ekr@rtfm.com> Wed, 28 May 2014 17:24 UTC

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From: Eric Rescorla <ekr@rtfm.com>
Date: Wed, 28 May 2014 10:23:49 -0700
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To: Martin Thomson <martin.thomson@gmail.com>
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Subject: Re: [TLS] Proposed text for removing renegotiation
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On Wed, May 28, 2014 at 10:02 AM, Martin Thomson
<martin.thomson@gmail.com>wrote;wrote:

> On 27 May 2014 17:44, Martin Rex <mrex@sap.com> wrote:
> > Conceptually, the TLS session cache is readonly after an entry
> > is created, and that is GOOD, i.e. full TLS handshakes create new,
> > distict session cache entries, and abbreviated TLS handshakes resume
> > existing session cache entries and *NEVER* modify them.
>
> That's a good point.  Something that I missed.  A resumption handshake
> would have to include an epoch from the previous session.  That number
> would need to be incremented with each update of the master secret.
>

That's one option. The other option is just to flush your session cache. To
the best of my knowledge, systems generally either have a lot of connection
setups (which makes session caching attractive) or long-lived connections
(where you would want to change keys) but usually not both.

-Ekr