Re: [TLS] Followup on Update

[Dave Garrett <[e-mail]>]

On Tuesday, February 24, 2015 07:44:22 pm Eric Rescorla wrote:
> Folks,
> 
> I'd like to get a sense of the WG on whether they want to pursue the Update
> mechanism [0].
> 
> There are several possibilities here, including:
> 
> - Just do basic Update
> - Move session ticket establishment to Update
> - Mode client authentication to Update
> 
> My sense from the discussion in HNL was that people were generally
> positive on basic Update and unsure on the other two. If that's right,
> I'll buff up PR#94 for merge into the spec (pending chair approval).
> 
> Thanks,
> -Ekr
> 
> 
> [0] See https://github.com/tlswg/tls13-spec/pull/94 for a WIP
> version of the basic mechanism.

The current proposal says:

"An implementation MAY send an UpdateRekey at any time after
the handshake completes."

Is there a particular reason to not just have an automatic rekey at semi-regular intervals? So, every N records or M minutes (or whichever comes first) an endpoint must send a rekey, and then after a similarly measured interval the other endpoint sends a rekey; repeat ad infinitum. This would also ensure entropy for rekeying comes from both endpoints equally over the course of the connection. I would expect it would be better to not rely on implementations all designing their own heuristics on when to send rekey updates, and also would avoid multiple updates being sent at the same time by each endpoint (and the possible pitfalls of doing so).


Dave