Proposal: Tor

See De-anonymizing Members of French Political Forums by Dominique Bongard presented at Passwords13 August 2013

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    Could you elaborate on your question? If a user doesnt use Gravatar, then this problem is solved.
    – asheeshr
    Aug 10, 2013 at 2:17

2 Answers 2


Why would we reconsider the Tor proposal? You do realize that if you're running Tor you shouldn't login to any services that know who you are anyway, rendering your point entirely moot. Instead of trying to create drama, why not find a way to make this into a good example question on using Gravatar with Tor. The answer of course is this: Don't login to anything when Tor is running, as you give up your identity as soon as you login.

The point is that you shouldn't be participating as a logged in user on Stack Exchange or any other site if Tor is active. Sure, it hides you, but it's not smart enough to protect you if you shout on the rooftops that Marsh Ray is now logging into Stack Exchange, or any other service -- Gravatar or no Gravatar.

When you're not running Tor, that's a good time to use Stack Exchange, Gmail, Github, your online banking, etc, when you're not trying to hide because, well, you're HTTP POSTing your identity all over the Internet anyway and Tor can't hide you if you're already telling everyone who you are. If you're not logged in, your Gravatar md5hash doesn't show up, so there's no problem. :)

The fundamental problem with the resource you point to is that the folks whose Gravatar gave them away shouldn't have logged into that service in the first place, as it gave them away the moment they typed in their email address and password, even without Gravatar. Again, the use of Gravatar is a moot point in that case as the fact that you logged in shows up in server logs. That's not a design flaw of Gravatar, it's a flaw in how those users were using the system and a flaw in the design of the political forum. Analogy: If you hide in the bushes, wearing a fake mustache and funny glasses, and then yell out "Yo I'm over here and my name is Marsh Ray" then you're going to be found.

The Stack Exchange Tor Q&A site isn't for discussing political dissension, so there's nothing to hide from here and hence no one should be too terribly concerned. If you are, don't use a Gravatar.

Hope this helps.

  • A user who has questions about Tor may prefer to ask them pseudonymously. The questions they ask may involve sensitive information, such as misconfigurations. SE claims "We take the private nature of your personal information very seriously, and are committed to protecting it" and "Other than in these rare circumstances, SE will not rent or sell potentially personally identifying information to anyone." (stackexchange.com/legal/privacy-policy ) A user might reasonably interpret that to think that their email address is private on StackExchange, yet gravatar icons expose it publicly.
    – Marsh Ray
    Aug 9, 2013 at 6:53
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    But mostly, this general dismissive attitude towards privacy ("there's nothing to hide from here and hence no one should be too terribly concerned") suggests that StackExchange is a poor fit for people who rely upon Tor.
    – Marsh Ray
    Aug 9, 2013 at 7:00
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    @MarshRay forgive me for not reading the entire presentation, but can't a user simply change their avatar to a different image and the problem is solved?
    – JohnB
    Aug 9, 2013 at 14:07
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    You make good points, @MarshRay, but you're forgetting that governments can confiscate server logs and even hire very expensive hackers. If someone wanted to know the names of all of the people who are users on the Tor SE site, and that someone is an expert hacker or a government official with the law and a judge on their side, it won't really matter whether or not gravatar is involved or not. But if you're that worried, don't use gravatar. SE has other options for setting avatar images. Hope this helps.
    – jmort253
    Aug 9, 2013 at 16:56
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    @JohnB Sure. Where is it documented that this is a requirement for a users email to be private?
    – Marsh Ray
    Aug 10, 2013 at 9:11
  • @jmort253 The deanonymization risk posed by Gravatar (and thus SE) isn't specific to state-sponsored hackers, it can be exploited by any reasonably competent adversary.
    – Marsh Ray
    Aug 10, 2013 at 9:11
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    @MarshRay - If someone wants to find your identity, they will, gravatar or not. The Web is just fraught with security issues. Even ixquick.com, a search engine claiming to be secure, shows your ISP what you're searching for by putting the urls in image urls like ixquick.com/proxy?url=http//super.paranoia.com. At any rate, trying to shut down a proposal over this is silly. This isn't the place for secure communications. It's a Q&A site.
    – jmort253
    Aug 10, 2013 at 15:15
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    @jmort253 "If someone wants to find your identity, they will, gravatar or not." In other words, StackExchange is a site unsupportive of the goal of strong anonymity.
    – Marsh Ray
    Aug 13, 2013 at 7:35
  • @jmort25 "trying to shut down a proposal over this is silly" My comment was directed at the Tor Project to reconsider their involvement with StackExchange, not the other way around. It seems I may have posted it in the wrong place.
    – Marsh Ray
    Aug 13, 2013 at 7:38

If you are concerned about anonymity on Stack Exchange there are two basic solutions as others already mentioned:

  1. Do not use Gravatar. You can upload your own image on Stack Exchange.
  2. Do not use personal e-mail address. There are many services where you can more or less anonymously create a new e-mail address. This solution would protect your privacy even if Stack Exchange was hacked or forced to reveal the personal data. To be really protected you have to use Tor or other anonymizing service (in a separate session from other activities!) to access Stack Exchange.

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