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Re: [TLS] ticket_lifetime and generic network layer

Ilari Liusvaara <ilariliusvaara@welho.com> Thu, 09 February 2017 19:05 UTC

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Date: Thu, 09 Feb 2017 21:05:30 +0200
From: Ilari Liusvaara <ilariliusvaara@welho.com>
To: Mark Dunn <mark.dunn@objectiveintegration.uk>
Message-ID: <20170209190530.GA20340@LK-Perkele-V2.elisa-laajakaista.fi>
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Subject: Re: [TLS] ticket_lifetime and generic network layer
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On Thu, Feb 09, 2017 at 12:38:50PM -0000, Mark Dunn wrote:
> I am reading your TLS 3.1 Standard and the mailing list.
> 
> It looks great. 
> 
> I am particularly interested in using the 0-RTT feature for IoT timestamped
> data, which would seem immune from replay attacks
> 
>  
> 
> I have a couple of questions
> 
>  
> 
> 1) The maximum ticket lifetime is set to 7 days. Is this based on hard
> science or arbitrary?
> 
> If it is arbitrary then 8 days for weekly intervals or 32 for days for
> monthly intervals would  make better commercial sense
> 
>                (allowing for variability in wake-up times for constrained
> devices)

AFAIK, it is arbitrary. However, long validity periods bring security
issues, with having to store and protect symmetric keys for a long
time.

> 2) Have you considered using TLS for a generic network layer?

Note that TLS requires in-order reliable delivery (DTLS doesn't, but
DTLS 1.3 is currently just handwaving), and neither is available below
transport layer.


-Ilari

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