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Unveiling secrets of the ESP32: creating an open-source MAC layer

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Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#11

Post by jcalvinowens »

icpmacdo wrote: post #5

I can attest to the challenges of the section on Dynamic analysis on real hardware and the struggles of attenuating signal interference on the ESP. Anyone have a recommendation on conducting fabric for RF isolation as briefly mentioned in the article or resources on the subject of rf isolation/Faraday cages for microcontrollers?

Based only on my own anecdotal experience... I think the hole the cables go through is the biggest problem in OPs setup. I'd solder the shields to the cage circumferentially around the hole. Shielded USB cables aren't too hard to find, it wouldn't be as good as something optical but it's a lot easier.

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#12

Post by rkfjrjrkfnrkd »

This is very interesting. I'm keen to get involved but, while I'm very experienced with ESP32, I don't have experience with this type of reverse engineering.

How long did it take you to get the environment and tools set up, so you could start digging in?

Is time or money a more valuable investment at this stage? If it's not too forward, how much would be useful to your organisation? (I can email if preferred.)

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#13

Post by finnjohnsen2 »

I wasnt aware of this wifi blob. This feeds a tiny paranoia I have at the back of my head when dealing with esp32/espressif. I have dozens of esp32s around and I love them, but Espressif is 100% Chinese.

Im uncomfortable with what I read that every company of significant size in China automatically requires CCP party members to be involved in the company at a high level.

So Im very happy to hear people such as these guys are looking deep at this.

Ofcourse since Espressif controls the hardware, so they can do anything eventually. My itch will always be there and Im going to switch once I find something made in preferably the EU when I find something comparable to esp32. Maybe Nordic Semiconductors will make some nice risk-v chips and dev-boards soon.

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#14

Post by cchance »

WatchDog wrote: post #10

The section on trying to attenuate outside wifi signals interested me. There is a bunch of hand wavy information on building faraday cages online, some people suggesting to utilize a microwave oven, since they operate at the same frequency. There are even wifi faraday cages for sale on amazon. However I can't really find much actual benchmark data online about how well these various approaches actually attenuate sign…

Not sure on specific numbers but based on the picture he posted of it in a can he would have probably done better with metal netting from a window screen or metal chicken wire it destroys wifi signal pretty damn effectively

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#15

Post by zamadatix »

WatchDog wrote: post #10

The section on trying to attenuate outside wifi signals interested me. There is a bunch of hand wavy information on building faraday cages online, some people suggesting to utilize a microwave oven, since they operate at the same frequency. There are even wifi faraday cages for sale on amazon. However I can't really find much actual benchmark data online about how well these various approaches actually attenuate sign…

If the product doesn't list some form of dB loss (at at least 1 frequency) I assume it's more or less just a standard box. Sometimes that'll be right, sometimes it won't. Some of it comes down to how you use the box as well. If you're feeding un-isolated power in via a big hole in the back then it doesn't really matter how perfect the front is at blocking signals.

I'm surprised their paint can only gave them a 10 dB difference. I've found simply wrapping things in aluminum foil is good for about 40 dB when it comes to Wi-Fi.

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#16

Post by ajsnigrutin »

finnjohnsen2 wrote: post #13

I wasnt aware of this wifi blob. This feeds a tiny paranoia I have at the back of my head when dealing with esp32/espressif. I have dozens of esp32s around and I love them, but Espressif is 100% Chinese. Im uncomfortable with what I read that every company of significant size in China automatically requires CCP party members to be involved in the company at a high level. So Im very happy to hear people such as these…

Wifi is easy... there's no way to send anything undetected, since you control the routers, etc.

GSM->5G modems are a lot harder to debug... maybe now in recent years with cheaper SDRs, but a lot harder then wifi.

And not sure why you'd be afraid of CCP, we saw the wikileaks, USA does a lot of similiarly bad stuff too and even got caught doing it... and if you live in a "western" country, USA has much easier access to you than China.

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#17

Post by reachableceo »

redfast00 wrote: post #6
icpmacdo wrote: post #5

I can attest to the challenges of the section on Dynamic analysis on real hardware and the struggles of attenuating signal interference on the ESP. Anyone have a recommendation on conducting fabric for RF isolation as briefly mentioned in the article or resources on the subject of rf isolation/Faraday cages for microcontrollers?

As part of the NLNet grant, I will build an affordable Faraday cage; I'll post the BOM, assembly process and a test report in a separate blog post.

I am researching that at this time as well. I have VNA etc and am keen to collaborate !

Charles@turnsys.com

I have quite a collection of research material on RF cages / testing .

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#18

Post by atVelocet »

icpmacdo wrote: post #5

I can attest to the challenges of the section on Dynamic analysis on real hardware and the struggles of attenuating signal interference on the ESP. Anyone have a recommendation on conducting fabric for RF isolation as briefly mentioned in the article or resources on the subject of rf isolation/Faraday cages for microcontrollers?

I used the isolation „fabric“ wrapped around the extension cable off a super cheap PCIe riser card. I put an iPhone inside which blocked WiFi, BT and 4G.

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#19

Post by pietervdvn »

reachableceo wrote: post #17
redfast00 wrote: post #6

Earlier quoted context omitted.

As part of the NLNet grant, I will build an affordable Faraday cage; I'll post the BOM, assembly process and a test report in a separate blog post.

I am researching that at this time as well. I have VNA etc and am keen to collaborate ! Charles@turnsys.com I have quite a collection of research material on RF cages / testing .

There is an email address at the bottom of the blog post, you can send directly there.

Re: Unveiling secrets of the ESP32: creating an open-source MAC layer

#20

Post by KRAKRISMOTT »

Max-q wrote: post #3

The article claims that the ESP32 costs $5. The reality is around half of that for the MCU, and around $3 for pre certified modules including crystal, PCB antenna or UF-L connector. So it's really affordable. Espressif has also launched a new ESP32C3 based on RISC-V, with modules priced at around $2.

That's the development unit price. ESP's MCUs have amazing value when you buy in bulk.
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