Re: [TLS] Fate of resumption

[Viktor Dukhovni <[e-mail]>]

On Mon, Oct 20, 2014 at 10:26:33PM -0700, Alex Elsayed wrote:

> > It's fairly straightforward to have connection 1 generate two keys,
> > M and M' from its PMS, use M to generate its keys and store M'
> > in the session cache. But this still leaves both connection 2 and
> > 3 sharing M'.
> 
> One thing I wonder - do we need to support multiple resumption of the same 
> state, or do we simply need to allow a session to die and revive?

In terms of existing practice Postfix resumes cached sessions
independently in parallel.  When a cached a resumed session completes,
no new session replaces the original cache entry.  The code assumes
that session resumption is non-destructive, and cached state can
be re-used multiple times.  I imagine similar behaviour patterns
apply to browsers, and other applications.

If TLS 1.3 changes session re-use semantics, it will be substantially
more difficult to deploy (changes will impact not just SSL library,
but also application code).

-- 
	Viktor.