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Re: [tor-talk] Wikimedia and Tor

On 10/01/2014 07:57 AM, Derric Atzrott wrote:
> Good day all,
> About once a year the topic of Tor comes up on Wikimedia's technical mailing
> list.  I recently raised the topic again.  For those who aren't aware of the
> situation, currently Wikimedia blocks all edits from Tor users.  We are trying
> to find a way that it might be possible for us to lift that block, while not
> exposing ourselves to the abuse that seems to inevitably come from Tor and
> other proxy services.
> The biggest concern that I have seen is how do we prevent sock puppets.  It
> seems that when Tor was unblocked it was regularly used by people who had been
> blocked from editing to evade those blocks.  There have been a couple of ideas
> thrown around in the past, but most of them have some sort of objection.
> I was curious if any of you here might have any ideas?  How can we verify that
> a person is who they say they are, and block them if they are abusive in such
> a way that it is at least difficult for them to evade the block, but that does
> not impose a requirement so high as to be prohibitive to those who aren't
> causing issues?

You can't reliably block by IP address. It's unfair, because numerous
users behind a NAT router will have the same public IP address. And it's
also trivial to evade using proxies, with or without Tor. Blocking Tor
(or even all known proxies) only stops the clueless. Anyone serious
about evading a block could just use a private proxy on AWS (via Tor).

> We've thought about setting up infrastructure for Nymble, but that would
> require Tor users to expose their IP address in order to get a Nymble token.
> We have also thought about blind signing certificates which are then used to
> verify a person is the same as before, but it would be trivially easy for
> someone to get a new one.  We've thought about putting all Tor edits into a
> review queue, but that imposes too high a cost on our other volunteers.
> Fingerprinting Tor users seems both unethical and difficult, requiring some
> form of donation seems unethical, difficult, and possibly illegal, and
> requiring accounts to be created without Tor exposes Tor user's IP addresses.

Even imposing a nontrivial cost for creating accounts (say 10 BTC) would
not help. Determined adversaries would pay it. And of course, that would
exclude numerous innocents who wouldn't or couldn't pay.

> We really don't want to collect private information from Tor users like phone
> numbers, government IDs, etc. as that information isn't collected for anyone
> else and seems especially sensitive for Tor users.

That would exclude numerous users living under repressive regimes. But
then, Wikimedia is already doing that by blocking edits by Tor users.

> A more personal note, this email is being sent from my work email address as
> I use it for list subscriptions (I spent 12 hours a day at work or commuting
> so this makes lists much easier to keep up on), but I will be signing my emails
> with my personal PGP key and any off-list messages to me should probably be
> directed there.
> Additionally it should be noted that I have a passing familiarity with Tor as
> both a user and recently became an exit relay operator, though if I missed
> something blindly obvious, definitely please point it out to me!

The bottom line is that blocking Tor harms numerous innocent users, and
by no means excludes seriously malicious users.

> Thank you,
> Derric Atzrott
> User:Zellfaze on English Wikipedia
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> =/It2
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