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Re: [TLS] Let's remove gmt_unix_time from TLS

Paul Wouters <paul@nohats.ca> Wed, 11 September 2013 16:40 UTC

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Date: Wed, 11 Sep 2013 12:40:31 -0400
From: Paul Wouters <paul@nohats.ca>
To: Russ Housley <housley@vigilsec.com>
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Cc: perpass@ietf.org, "tls@ietf.org" <tls@ietf.org>
Subject: Re: [TLS] Let's remove gmt_unix_time from TLS
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On Wed, 11 Sep 2013, Russ Housley wrote:

> The tlsdate program (with origins in the TOR project) makes use of this value in the nonce portion of the handshake.
>
> I think that the time is an important part of the nonce.  Even if the implementation has a crappy random number generator, the time value does a good job of ensuring that the nonce value is not repeated.  Obviously, the time value does not help with the unpredictability, but the random value is supposed to do that.

Note that tlsdate is a stowaway on board a TLS server. If we can
accomodate, then fine. But we shouldn't go out of our way to support it.

Between making tls less vulnerable to fingerprinting (which helps tor)
and supporting tlsdate, I'd opt for the former.


Paul

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