[tor-dev] Implement JSONP interface for check.torproject.org

[Robert Ransom]

On 2012-03-23, Arturo Filastò <art at baculo.org> wrote:

> Since I noticed that check.tpo was removed from the front page I was
> thinking it would be a good idea to bring back up the topic of migrating
> check.torproject.org to a JSONP based system.

JSONP gives the party which is expected to provide a piece of data the
ability to run arbitrary JavaScript code in the security context of
the website which requested the data.  The Tor Project should never
put itself in a position to have that level of control over other
parties' websites.


> Such a system would also allow to have the "JSONP check nodes" distributed
> across multiple machines (avoiding the single point of failure that check
> currently is) and the client side software could be embedded inside of
> TBB directly.
>
> People could further promote the usage of Tor by placing an "Anonymity"
> badge on their website.
>
> A person wishing to setup such a node needs to simply install TorBel
> and a python based web app that runs this JSONP system.
>
> My threat model for this is very lax, so I don't see any purpose in
> bad actors telling a client when he is not using Tor that he is using it.
> If check.tpo tells the user is not using Tor it already means that TBB
> failed, the purpose of it is just to provide visual feedback to the user
> that all is did went well.

check.torproject.org is the only service which can warn Tor users that
a security upgrade is available for the Tor Browser Bundle.

It is also accessed by every Tor Browser Bundle as the first page
shown after the user uses the ‘New Identity’ Torbutton command; any
party which can impersonate check.torproject.org can plant
user-tracking cookies in every TBB user's browser.

check.torproject.org cannot ever be run by untrusted parties, and
cannot ever use a JSONP service provided by untrusted parties.


> If check is moved to git and you think it is a good idea I can start
> working on this.

It is a more horrible idea now than it was the first time you proposed
it.


Robert Ransom