Snowden and co-designer Andrew “Bunnie” Huang gave a presentation at the MIT Media Lab in Cambridge, Massachusetts on Thursday via video link, the Guardian reported.

They exhibited how the device connects to a phone’s different radio transmitters, showing its owner knows when a cellular, Wi-Fi or Bluetooth connection is being exploited to share or receive data.

Initial designs of the casing, called the introspection engine, have a small, monochromatic display which shows whether the phone is “dark”, or whether it is transmitting data.

The device is still an academic project and it is not ready for mass marketing yet, but could still influence how consumers view smartphones that they rely on every day, but actually they are “tracking devices.”

“If you have a phone in your pocket that’s turned on, a long-lived record of your movements has been created,” Snowden said.

“As a result of the way the cell network functions your device is constantly shouting into the air by means of radio signals a unique identity that validates you to the phone company,” he added.

“And this unique identity is not only saved by that phone company, but it can also be observed as it travels over the air by independent, even more dangerous third parties.”

Snowden, former NSA and CIA contractor, began leaking classified intelligence documents in June 2013, revealing the extent of the NSA’s spying activities, including the massive collections of phone records of Americans and foreign nationals as well as political leaders around the world.

Snowden, who lives in Russia where he has been granted asylum, has said that US government surveillance methods far surpass those of an ‘Orwellian’ state, referring to George Orwell’s classic novel “1984,” which describes a society where personal privacy is continuously invaded by spy agencies, Press TV reported.

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