If a wifi password is required to make full use of the device, I will return it.

If some users want to sacrifice security and privacy for "convenience", that's on them. But if you want to sell me the product, at least provide the option to decline without loss of functionality. Otherwise, no sale.

As an example, I refuse to buy a doorbell camera that doesn't support RTSP.

I feel like that is something that doesn’t or at least shouldn’t require a string of IoT devices, apps, wireless communication and hubs. Why not leave all of that out and just attach an air quality sensor to the air purifier and a small LCD to adjust the settings?

The light in my hallway turns on automatically when I walk past. No cloud, no HomeAssist, no WiFi, no Zigbee, no apps, no batteries to change. Just a motion sensor hardwired to the light fixture. Hasn’t failed me once in the past ten years. Works great even if the network goes down.

  Give a man a fish, and you feed him for a day.

For owners of ESP32-based IoT devices:

  Teach a man to fish, and you feed him for a lifetime.

blog author: https://x.com/jmswrnr

Every time I was part of a team designing IoT devices, there would be a slightly more security-focused engineer who would manage to have some level of protection for the boot. I'm surprised there was no resistance here to dump and reflash the firmware. Why would they not even bother encrypting the flash? How common is that?

It would have been nice to give the product name.

re: the notes on the use of the device keys (stored in the K/V store), assuming that they are per device would seem the most obvious vs that they are global. Global keys would be written in the main app body in my experience, not the KV store (but that doesn't mean people have not done unusual things here of course!).

I also want to share some feedback on the complexity of managing per device keys these days and the risks - there are lots of easy to use tools that per device keys like this much simpler to do in 2025 than 2015 and cloud platforms that take in CSV files and return very similar messages... Typically a security model for a device such as an air purifier can be easily defined as not having device encryption enabled if it has per-device keys on as the impact of breaching a single device remains compartmentalized to a single edge component and in this case, just a purifier (vs a car or something that explodes!). Not that I agree with this, but corporate security can! Device encryption causes lots of problems in factories that are often best 'ignored' if the product can afford it.

Per another comment, god bless ESP32 developers once the EU rule kicks in in August... !

Wonder why the company didnt just go with a standardised solution - seems more cost effective than rolling their own!

In this case, it would have been pretty hard to create a certificate if you couldn't read the firmware.

But, also pretty impressed at the same time. I think this is the first Hacker News article I've read about an ESP32 IoT device which has any encryption at all.

You really went through the whole reverse engineering process end to end, I know that must have been a ton of work to not only reverse engineer it but also to write everything up!

> We're not certain if each device has its own unique private key, but whether it does or not, both have downsides ... If all devices share the same firmware private key, the attacker needs to reverse engineer just a single device to MITM attack any other devices.

If anything, this article further highlights that security on these type of devices isn't as rigorous as other consumer electronics like laptops or smartphones. Anyone using smart devices should look into DD-WRT, OpenWrt, Tomato, or Asuswrt-Merlin and isolate these devices in their own VLAN away from the rest of your private network.

This is definitely beyond my capabilities at this point but it could be interesting to go through a similar process once mentally ready.

Of course, in 2025 this means "I really did find a device!"

I couldn't do 10% of this, and don't wish to spend a part of my life wrestling with gadgets like this. Simply will not buy. Also simply will avoid most all social media.

Knowing that might help influence purchasing decisions for those also interested in a "sleek" air purifier that contains an ESP32.

Makes me want to do the same on some devices I have.