Matt BlazeNov 7, 2024

Three people recently asked me about Faraday cages (to prevent their phones from being tracked), probably because of this blog post from a few years ago: https://www.mattblaze.org/blog/faraday/

Tl;dr:

- You probably don't need a Faraday cage. If you need to use your phone or have it on to receive calls/texts, a Faraday cage won't help you!

- The main use of a Faraday cage is to provide *assurance* that your phone is really off and not broadcasting your location.

- If you *do* need one, get a good one.

Matt Blaze: Testing Phone-Sized Faraday Bags

Show threadMatt BlazeNov 7, 2024
Also, while I'm as much as gadget freak as anyone, "get yourself a Faraday cage" would probably be very low on my checklist of things to do to prepare for an authoritarian dictatorship.
Show threadMatt BlazeNov 7, 2024
Also, if you've got this romantic idea that you're going to be some kind of superspy underground resistance operative staying one step ahead of The Man with your clever technology countermeasures, consider that ACTUAL TRAINED CIA SPIES have trouble doing this properly in practice, even for just a few weeks. See this talk from Blackhat 2013 https://www.youtube.com/watch?v=LWtbwMp7Zh8
OPSEC Failures of Spies

YouTube
Show threadhardyjohnsonNov 7, 2024

@mattblaze where do you fall on at least implementing the suggestions in the EFF Surveillance Self Defense Guide?

https://ssd.eff.org/

Surveillance Self-Defense

We’re the Electronic Frontier Foundation, a member-supported non-profit working to protect online privacy for over thirty-five years. This is Surveillance Self-Defense: our expert guide to protecting you and your friends from online spying. Read the BASICS to find out how online surveillance works. Dive into our TOOL GUIDES for instructions...

Show threadMatt BlazeNov 7, 2024
@hardyjohnson Rule One (and Two and Three) is Understand What Your Threat Is and What Problem You're Solving.
Show threadWulfy—Speaker to the machinesNov 7, 2024

@mattblaze @hardyjohnson

Also, since we're talking #FaradayCages

There are two scenarios here.
Containing a radio signal from leaving (metal tin ok)

EMP pulse strike. Complicated formula that includes thickness and type of material and mesh vs solid. I looked into it. Lots of good data from the cold war tests. Because we're talking very high energy.

Show threadMatt BlazeNov 7, 2024
@n_dimension @hardyjohnson I'm not sure where you're getting the idea that a metal tin is OK. Every metal tin I measured was terrible. Getting a good uniform low-resistance seal on a metal tin is surprisingly hard.
Show threadhardyjohnson

@mattblaze @n_dimension

Matt, I realize now I jumped into the middle of a thread with a question only tangentially related to your initial postulation and will withdraw from this conversation.

Nov 7, 2024 at 4:41pmWeb