How to make Secret Phone calls using a Mobile phone – Schneier
His step-by-step instructions for making a clandestine phone call are as follows:
- Analyze your daily movements, paying special attention to anchor points (basis of operation like home or work) and dormant periods in schedules (8-12 p.m. or when cell phones aren’t changing locations);
- Leave your daily cell phone behind during dormant periods and purchase a prepaid no-contract cell phone (“burner phone”);
- After storing burner phone in a Faraday bag, activate it using a clean computer connected to a public Wi-Fi network;
- Encrypt the cell phone number using a onetime pad (OTP) system and rename an image file with the encrypted code. Using Tor to hide your web traffic, post the image to an agreed upon anonymous Twitter account, which signals a communications request to your partner;
- Leave cell phone behind, avoid anchor points, and receive phone call from partner on burner phone at 9:30 p.m.—or another pre-arranged “dormant” time—on the following day;
- Wipe down and destroy handset.
PRACTICING GOOD OPSEC
Central to good privacy, says Wallen, is eliminating or reducing anomalies that would pop up on surveillance radars, like robust encryption or SIM card swapping. To understand the risks of bringing unwanted attention to one’s privacy practices, Wallen examined the United States Marine Corps’ “Combat Hunter” program, which deals with threat assessment through observation, profiling, and tracking. The program teaches Marines to establish a baseline to more easily key in on anomalies in any given environment.
“Anomalies are really bad for what I’m trying to accomplish—that means any overt encryption is bad, because it’s a giant red flag,” Wallen said. “I tried to design the whole system to have as small a footprint as possible, and avoid creating any analyzable links.”
After establishing these processes, Wallen began researching cell phones. As expected, it involved a lot of trial and error. “I was going out and actually buying phones, learning about different ways to buy them, to activate them, to store them, and so on,” said Wallen, who eventually bought a burner phone from a Rite Aid. “I kept doing it until I felt like I’d considered it from every angle.”
When it came to protecting cell phone hardware, Wallen turned to Faraday bags. Invented by English scientist Michael Faraday back in the 19th century, Faraday cages were developed for modern usage with intelligence agencies, law enforcement, and the military in mind. The cages, which can be any type of container, feature metallic shielding material that blocks radio cell, Wi-Fi, and Bluetooth connections. Now available to the public, people can transport or store their electronic devices in Faraday bags, preventing hackers, law enforcement, and spies from accessing their private data
How to make a Faraday wallet