Block directory authorities, is it possible?

[Kevin Smith]

> > Why hasn't Tor been blocked in China already?

> 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?
>
> > Could it be that Tor is being used to help identify suspected
> > dissidents?

> 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. :)
>
> --Roger
>
>

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.