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

Hanno Böck <> Wed, 11 September 2013 16:53 UTC

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Date: Wed, 11 Sep 2013 18:53:29 +0200
From: Hanno =?UTF-8?B?QsO2Y2s=?= <>
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Subject: Re: [TLS] Let's remove gmt_unix_time from TLS
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On Wed, 11 Sep 2013 11:43:53 -0400
Nick Mathewson <> wrote:

> Despite the late date, much of the world is still not
> synchronized to the second via an ntp-like service. This means
> that different clients have different views of the current time,
> which provides a fingerprint that helps to track and distinguish
> them.  This fingerprint is useful for tracking clients as they
> move around.  It can also distinguish clients using a single VPN,
> NAT, or privacy network.  (Tor's modified firefox avoids this by
> not sending the time.)

I can't help getting the feeling that you're trying to fix the wrong
thing here. People use computers with a wrong clock. That's the problem
here. You should try to fix that and not workaround it.

My suggestion: Tor could detect on startup if the time is correct via
ntp (or even through the tor network itself with the next server). If
its not, it refuses to start unless an option like
"iknowmytimeisbrokenandidontcare" is set. For the gui, issue a warning
and an easy option to fix the time.

Hanno Böck