Chances are you have been told repeatedly to put your phone in a Faraday Bag when attending a protest, while crossing a border, to protect your device from being tracked, and information from being extracted.
Faraday bags are a more accessible way to have a portable version of a Faraday cage:
The metal construction of Faraday cages can deflect external electric charges and scatter them across its surface. This then creates an electromagnetic shield to counter the external waves. Positive and negative fields counteracting each other.
Microwaves and elevators are an everyday example of how Faraday cages function. They’re essentially metal boxes. Microwaves try to keep the waves inside while you are heating up your food. In elevators, it is often difficult to get reception on your phone, depending on your carrier. The metal box-ness of the microwave and elevator help to ward off the ingress and egress of specific electromagnetic waves.
Faraday Cage ≠ Faraday Bag
The problem, however, is that everyday Faraday bags do not carry over from Faraday cages as well, and not all Faraday bags are created equal. Many consumer-grade bags are poorly made and can create a false sense of security. So for the everyday carrier, do not consider them foolproof or airtight.
Let us explore some of the ways a Faraday Bag can be easily compromised.
Selective Blocking
Most Faraday bags are designed to stave off Wi-Fi, Bluetooth, cellular signals, RFID, and EMPs (electromagnetic pulses) in a specific frequency range. People often assume all bags will protect you around all frequencies. This is simply not true. None are designed to block every single frequency. Most Faraday Bags only block some, but not other frequencies. For instance, one bag might block cell signals but not GPS, Wi-Fi, or Bluetooth frequencies.
The Composition of a Faraday Bag
For their construction, Faraday bags usually start with an inside layer made with woven fabric metal or mesh out of materials such as nickel, copper, or aluminum.
Then there is often an additional layer of material such as Mylar or a similar metal coated material:
And finally, there is a protective outer shell, often made of materials like nylon or plastic, for durability topped off with Velcro, re-sealable strips, or magnets for their closure.
Repetitive Compromise
It is additionally important to understand the degradation of the metal mesh and material often used to line Faraday bags over time. When you open and close, fold, or crease this material repeatedly, it can wear out the surface and create a gap large enough for some waves to then pass through. This means your Faraday bag is no longer a Faraday bag, but now just a bag.
An example of this material compromise can be seen in the many cables we use every day around us. You may have come across a worn or breaking charging cable to get a glimpse into the inside.
Inside the external jacket of the cord itself (frequently made with PVC), there is often a foil wrap and/or braided metal around the wires inside. Shielding in good cables serve a similar Faraday purpose. The metal jacket keeps the signals inside the cabling so that they don’t interfere with other signals and vice versa. But these cable housings can easily wear out and breakdown, compromising the cable and protection.
This is why, by the way, it is not ideal to fold cables tightly because that can damage the shielding. It is instead recommended that you loop them loosely. Again, we, as humans that jam everything into our bags and pockets, do not or cannot often consider these factors.
Closing the Bag
The Faraday bag’s seal, whether Velcro, resealable slider, or magnet, can also prove to be a weakness. It is too easy to not press down on a resealable slider all the way, or to accidentally not seal Velcro folds fully. These often get worn out or accumulate particles to prevent proper seals. And then, there is always the matter of common human error. If you don’t close it completely, or open it even once, that is all it takes for your data to be swept up.
Opening and Reopening Faraday Bags
Imagine you are underwater, carrying a waterproof bag with your phone in it. If you open up the bag while underwater, water will get in. Even if you open the bag one time for one second. One time is all it takes to gain access to your device.
The water here represents malicious entities such as agents of the state, trying to steal your information using devices like Stingrays (aka ISMI Catchers) to spoof cellular towers, or geo-fencing to broadly capture swaths of devices that are present at a specific time and location.
If you do use a Faraday bag, your phone should be off and inside the bag for the entire duration of time you are trying to protect yourself. Most people, however, use their Faraday bags almost like a regular bag. They’ll have their device inside the Faraday bag, but turned on, and open it periodically to check it. Opening it even one time is enough to compromise the entire setup.
Many Transmitting Devices
For all of these reasons and more, most people, when using Faraday bags for their devices, use them incorrectly, impatiently, or in ways that render them ineffective. Additionally, people often forget to consider all of the other devices that emit signals besides your phone, such as wireless ear pods, headsets, smart glasses, key fobs, tracking tags, smart watches, smart rings, smart necklaces, and anything that communicates with wireless-enabled frequencies.
Who Do We Think We Are?
We the humans often cause more exploitable vulnerabilities in these scenarios. It is like inviting a random person into your closed Signal group, or using Proton email but writing “TOP SECRET: meet at the south corner at noon” in the subject line. The technology can be wonderful and powerful, but there are so many factors to binding that privacy and security that need to happen together.
So, all of those factors including quality and variation in manufacturing, differences in blocked frequencies that you would need to test, the closing mechanism, material, wear and tear, and of course human error. Everything needs to be perfect for a Faraday bag to work perfectly, and even so, there can be flaws. We humans are not perfect, and we should not try to be either. We should understand this beautiful fact of humanity when we use protection.
If you do use a Faraday bag, keep in mind they are never perfect; they can dampen the amount of discovery, but they can also seep out information relatively easily.
Dampen and seep.
This is why when you truly want to remain undetected by your device, it is recommended that do not carry your device at all.
If you are more concerned about the amount of data being taken over your identity being detected and identified, you can consider a stripped down Simplified Phone with the bare minimum installed on it instead, one that is not used as your primary device. A Simplified Phone’s purpose is not anonymity, but rather to reduce the amount of unnecessary data being exposed.
This is different from what is known as a Burner Phone, whose purpose is for anonymity and to remain untraceable. Having a true Burner Phone is not as accessible to most, as there are several careful steps that are required to accomplish this.
This is why for most, a Simplified Phone is an easier entry point.
I will cover specifics on both the Simplified Phone and Burner Phone in future posts.
More to come in digital security and data privacy. Stay secure and private out there.
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