Edward Snowden - the man who leaked classified information from the National Security Agency (NSA) in 2013 and who is hailed by some as a whistleblower and condemned by others as a traitor - has co-created a conceptual iPhone case intended to prevent governments and various other parties from spying on smartphone users.

Smartphones, are of course, easily trackable - a "perfect tracking device" in Snowden's words - and both governments and criminals can obtain all sorts of information about users (including the users' locations) by monitoring signals emitted by phones. Such surveillance can jeopardize the safety and effectiveness of both activists and journalists; at least one journalist, Marie Colvin, is believed to have been killed in Syria after signals from her phone were used to establish her location as a target.

Of course, modern smartphones have "Airplane" modes that theoretically shut off transmissions. But such modes don't really terminate all communications - GPS often remains on, and some other communications may also still occur. I have, for example, received text messages while sitting on the New York City subway with my phone in Airplane mode; someone looking to see where I was could send a series of texts and look for a beeping phone. Malware on a phone could also theoretically allow the phone to display that it is in Airplane mode when it is not.

Snowden and hardware hacker, Andrew Huang, co-authored a paper presenting a possible solution to this problem: they proposed a smartphone case that is connected to the phone and alerts the user when the phone is making transmissions. The case - which they dubbed the "introspection engine" --  contains wires that feed into the phone via the SIM card slot and attach to various components inside the phone. The case utilizes its own computer and display; the display shows status information for phone communications (GPS, Bluetooth, WiFi, cellular service), and the case can set off an alarm if it detects an occurrence of unusual activity.

Snowden and Huang presented their paper this past Thursday at the MIT Media Lab; Snowden obviously did not attend in person; he video-conferenced in from Russia where he is currently living as a fugitive, wanted by law enforcement in the United States.

At this point, the "introspection engine" is just a concept - no prototype even exists yet - and, while the case may have value to a select small group of people, it is unlikely to become widespread.

For most people, turning off one's smartphone is sufficient to prevent it from making transmissions. Worried about malware that fakes a power-off? Place your device in a Faraday type case that blocks transmissions; various models of such cases are sold online and there is a new high-end model with all sorts of other security features being shown at the  HOPE Conference currently underway in New York. Of course, such cases are not 100% perfect - but, for, most people, they suffice - and, even in the case of journalists in rogue nations such cases might already offer sufficient protection.

Unlike Faraday cases, the proposed Snowden case doesn't block signals - it just warns when a signal is being sent and, if an optional kill switch is added, kills the transmission - so, in highly sensitive situations, it might still pay to use the Faraday case around the phone even if the device sports an "introspection engine" type case.

Also, note that if someone wants to use the phone feature at times, but wants to ensure that the phone isn't making unauthorized transmissions, the case itself isn't going to do much, as it cannot detect if extra information is going out via the cellular connection when that connection is in use. What it might catch are packets being sent at irregular times or if cellular data is sent when that feature is showing on the phone as being disabled, and the user intends to use only WiFi.

Another approach might be far simpler than the "introspection engine" - if you are going into a place where you need to worry about transmissions, use an old non-connected organizer and camera, and use a non-smart-phone phone with a removable battery - and keep it is a Faraday Box even when it is off.

I am also not sure how much protection the Snowden case actually provides against government spying. Governments have the ability to track users through the wireless providers in their respective regions - they don't need to hack cellphones and program the devices to make unauthorized transmissions in order to track people's locations.

The "introspection engine" is certainly interesting - although I suspect that if it had been invented by someone less famous, not many people would have even taken notice. And, as it is just a theoretical object at this point, nobody can say for certain if it would even work as intended. As Snowden hopes to work on developing a prototype, time will tell.