Why hasn’t Tor been blocked? III
I posted a portion of my last post, Why hasn’t Tor been blocked? II to the or-talk mailing list and received the following response from Roger Dingledine, one of the lead Tor developers:
Me:
Why hasn’t Tor been blocked in China already? Torpark is redirecting to the Google homepage. The psiphon homepage has been blocked. The Freegate homepage is blocked. Why not Tor?Roger:
My guesses, in order of ease-of-explanation:A) There are perhaps 30000 people in China running Tor clients right now, according to my rough estimates. That’s roughly zero people, in China.
B) The general perception of Tor is that it’s a tool for experts. So they don’t think they need to block it (yet).
C) We haven’t publically threatened their control. By emphasizing government/military/law enforcement use, and individuals in free countries who need their civil liberties, we don’t force them to take action.
D) Other?
Me:
Could it be that Tor is being used to help identify suspected
dissidents? Consider the following:I’m sitting at my home in Beijing using Tor. The Chinese internet police see my computer periodically connecting to a Tor directory
[snip]
national elections. Not too likely that he is a dissident.Wang Guolu is sitting at home using Tor. The Chinese internet police
[snip]
of being a member of the FLG. A relatively low paid factory worker using advanced internet anonymizing software? That just screams dissident.Roger:
As I understand it, social networking attacks are much simpler and more successful. Having an informer at the factory is much more straightforward, and just the *possibility* of it is usually enough to make a lot of people self-censor.In fact, as countries restrict more information at their national firewall, they end up with *more* Tor users — not because they’re all dissidents, but because they want to read the web comics or stock market sites they were able to read last week. The mere fact that you use Tor in these cases is not “much” evidence on you, as long as there’s a sufficient population around you using Tor.
So yes, they could do what you describe, but there are many things they *could* do, and from talking to people in China, this probably isn’t first in line in terms of worries. But let me know if you disagree.
My response
I agree with you that it is unlikely that monitoring Tor users plays much if any role in identifying dissidents in China given its relative complexity when compared to other methods, however I am still perplexed as to why Tor has not been blocked. If reasons A) and B) are true, then why does the Torpark download reroute to Google’s homepage? Torpark users are a subset of Tor users, and I would imagine that Torpark users in general are more experienced computer users as well, ie., wouldn’t Torpark also be perceived as a tool for experts? Furthermore, why has the psiphon homepage been blocked? Users of psiphon in China are likely far fewer than users of Tor, and because psiphon essentially requires Chinese users to have a trusted contact running a psiphon server abroad the likelihood of psiphon ever becoming as popular or as useful as Tor is in China is nil.
Reason C) seems pretty reasonable, and also provides a reason as to why both Torpark and psiphon have been blocked.
From the Torpark Support page: “Your donation can help bring democracy to those who have no choice, freedom of speech to those who are silenced, and break down the walls of censorship worldwide.”
http://torrify.com/support.php
From the psiphon homepage: “psiphon is a human rights software project … that allows citizens in uncensored countries to provide unfettered access to the Net through their home computers to friends and family members who live behind firewalls of states that censor.”
http://psiphon.civisec.org/
On the other hand, the Tor developers have publicly made note of the ability of Tor to circumvent the Chinese firewall, calling China “a global active adversary with a lot of manpower and money, and severe penalties to discourage people from trying.”
http://wiki.noreply.org/noreply/TheOnionRouter/TorFAQ#China
Given the fact that access to these smaller projects has been blocked, I think the “Tor is small enough to be flying below the radar” argument has some strikes against it. I think there must be some other reason(s) in addition to this one as to why Tor has not been blocked. But what is that reason?
