Tor is a system designed to improve users' privacy and security by protecting their internet usage from traffic analysis. This is achieved by transmitting data packets through a random subset of the relays provided by Tor participants.

In addition, Tor browsers are normally configured to protect against browser fingerprinting, which can be used to identify an individual browser based on the information it sends to servers. (I just visited the EFF's Panopticlick site and found the configuration of the browser I used was unique among the nearly four million tested.)

Tor descends from the Onion Routing program at the US Naval Research Laboratory.

Back in December 2013, the Tor Project was notified by users that the Tor Browser iOS app in the App Store contained adware and spyware, so the Project lodged a complaint with Apple.

According to the Project's ticketing system, Apple responded saying the app's author was being given a chance to defend the allegation.

Despite additional approaches by the Project, Apple apparently did nothing further.

Then this week Tor Project leader Roger Dingledine noted in the ticketing system "I mailed Window Snyder [security and privacy product manager at Apple] and Jon Callas [CTO of Silent Circle and Blackphone, and a former senior scientist at Apple] to see if they can get us past the bureaucracy."

He added "Otherwise I guess plan C is to get high-profile people on Twitter to ask Apple why it likes harming people who care about privacy. (I hope plan B works.)"

Mr Dingledine did not mention who, if anyone, he approached, but a tweet from Runa A. Sandvik of the Center for Democracy and Technology - "Dear Apple, please take down the fake #Tor Browser Bundle you have in your App Store." - is being given implicit credit in some quarters. Ms Sandvik's message was retweeted around 100 times.

The app in question has now been taken down.

Last month a fake Tor app was spotted and removed from the Microsoft app store.