Snowden, currently living in asylum in Russia, and Huang released a report detailing their design, though a prototype has yet to be made.
Their proposed device would be a shell resembling an external battery that goes over the outside the iPhone, but it would be connected to the phone's SIM card and warn the user if the phone's radio is transmitting when it isn't meant to be.
"This work aims to give journalists the tools to know when their smart phones are tracking or disclosing their location when the devices are supposed to be in airplane mode," Snowden and Huang said in the report.
Huang said in Wired magazine that the project was more focused on protecting journalists from foreign governments that have acquired increased ability to compromise phones, like the Syrian regime of Bashar al-Assad, than from US agencies like the National Security Agency.
Huang, a US citizen based in Singapore, holds a doctorate in electrical engineering from the Massachusetts Institute of Technology.
Snowden and Huang said they hoped to release a prototype within a year.