Yet another Hacker News

Reverse Engineering My Coway Air Purifier to Ditch the Cloud

171 points scottjg 17 hours ago 35 comments

bombcar 1 hour ago | parent

I took a Vornado TRANSOM, a Broadlink RM4, and a Shelly Smart Plug, a Qingping Air Quality Monitor Gen 2 + claude and HASS, and now I have a fan that turns itself on when the CO2 level gets too high.

And I can override or change it from Apple Home.

The smart plug lets it verify that the fan is actually running, (because it measures usage) and we worked out that after a power cycle the Vornado goes back to a known state, and we can find the speed by forcing it all the way to 4 and then stepping back.

nijave 1 hour ago | parent

Small world, just submitted PRs to add Vornado Strata 433mhz decoder to rtl_sdr :)

Need to try to get Sonoff bridge rigged up next but have been busy messing with Hatch alarm

deadbabe 1 hour ago | parent

I love how it has become a trend now to take some device that required a cloud subscription, reverse engineer it, then connect it to your own server you control.

Suddenly there are so many products to play with that would have previously been undesirable! This is one of the good things AI has enabled.

jerf 1 hour ago | parent

Enjoy it while you can. You can see the AI companies have already started the process of locking us out of this, with Opus 5.5.

God forbid our fans, our fans of all things, might be broken of their dependencies on the internet. The plebians can't be allowed to do that. Every relay must be cloud-connected so it can be monetized and disabled for whatever dumb ass reasons someone might want to disable it.

Zopieux 1 hour ago | parent

Just use abliterated/uncensored self-hosted models. This is why we need them and the hardware to run them. Yes, the API models which will further close the walled gardens will evolve faster than the open-weights ones, but I'm hopeful about the community as a hole rejecting this status quo.

elephanlemon 37 minutes ago | parent

Is there hardware you would suggest that you can actually buy today? Pricing is out of control right now, if you can even find stock.

ed312 7 minutes ago | parent

An RTX4090 or a 128gb macbook can generate a pretty reasonable number of tok/sec. Those are not cheap, but within the realm of serious hobbyist. I really hope the AI bubble deflates a bit so consumers can get more powerful hardware at the low thousand $ range.

r_lee 48 minutes ago | parent

at least current models are safe, glm is very capable in terms of RE

nijave 1 hour ago | parent

This one yeets in a CA insecurely but eMudhra has been a gift for any that bake the CA--especially the abandonware unlikely to ever get patched.

ACCount39 20 minutes ago | parent

Unironically a gift. On your own home network, the one most likely to MITM you is yourself. And eMudhra's fuckup allows for a nice attack on a few devices you'd otherwise have to disassemble to pwn.

phillmv 1 hour ago | parent

i truly wish these things were not smart in the first place

noja 1 hour ago | parent

I have a light with a controller on the cord: brightness up/down, power. I can't use a smart plug with it because it always defaults to off. Any ideas?

bluGill 1 hour ago | parent

Cut the controller off and use the smart plug to control brightness. You might need to open it up and replace the power supply.

I'm going to guess that you will spend more money on this than just buying a light that has smart features compatible with your smart home ecosystem. You can't mix two smart systems on one cord - this has never worked. Where to put the smart is a tricky question as there are pros and cons to every answer, but in general the smarts need to be in exactly one place or things won't work.

king_crimson 34 minutes ago | parent

How would one control brightness via a smart plug?!

fusslo 22 minutes ago | parent

turn it on/off really fast

The relay clicking is a feature so you can tell the brightness audibly :)

fred_dawg 15 minutes ago | parent

Smart outlets that support dimming. You also need a dimmable bulb, but these are generic and cheap compared to a smart bulb.

varispeed 1 hour ago | parent

On topic, can you recommend a good air purifier to run in the office? 500 sq ft?

I am tired of having dust everywhere.

bethekidyouwant 55 minutes ago | parent

a box fan and a furnace filter.

poszlem 2 minutes ago | parent

To people who think this is a joke, it isn't: https://en.wikipedia.org/wiki/Corsi%E2%80%93Rosenthal_Box

micromacrofoot 52 minutes ago | parent

Coway are some of the best, and there are many dumb models without internet access at all

If you don't mind the hum of fans, it's hard to beat a Corsi-Rosenthal box... there are kits from cleanairkits.com or cybernightmarket.com to build quiet PC fan based boxes that in my experience work excellent and can use off-the shelf filters and parts

Zopieux 1 hour ago | parent

I'm a simple man. I see people freeing their devices from proprietary clouds and reclaiming ownership, I upvote.

microtonal 1 hour ago | parent

I am a simple man. When I see people buy devices with Zigbee, Z-Wave, or other fully local protocols, I nod. When I see people reward vendors that lock in with their money, I shake.

toomuchtodo 47 minutes ago | parent

How do you feel about Matter [1]? Asking as someone all in on Home Assistant, open local protocols, and ready to reverse engineer and spend whatever is needed for digital sovereignty, for both myself and the community.

[1] https://en.wikipedia.org/wiki/Matter_(standard)

amluto 42 minutes ago | parent

In my experience, Matter is okay except that it’s built over IP and manufacturers seem to be unable to resist using that juicy IP connection to talk to the Internet.

Thread should not have allowed Internet connectivity by default.

LoganDark 28 minutes ago | parent

My Brighter lamps don't connect to the internet. But, the smart features don't work properly, so maybe they're just shot in general.

NotOscarWilde 15 minutes ago | parent

(Not the OP, but want to spread awareness, sorry.) The Wikipedia page already lists the greatest disadvantage:

> (..) the ability to commission a finished product into a Matter network in the field mandates certification and membership fees, entailing both one-time, recurring, and per-product costs. This is enforced using a public key infrastructure (PKI) and so-called device attestation certificates.

Matter is designed to necessitate phoning into the internet for certification, which allows all manufacturers to just easily add-in phoning into the internet for telemetry. Furthermore, it does not define exactly which functionality must remain if a device is disconnected from the internet for a long time (assuming the user is trying to avoid sending out telemetry, not even bypassing certification).

huijzer 35 minutes ago | parent

What I don’t like about Zigbee though is that it is on the Wifi band so every device with wifi antenna can snoop on it. Even assuming the protocol is secure, anyone can infer patterns and devices based on traffic shape. For example, a motion sensor that sends data whenever someone walks by. In the end, nothing beats physical wires in terms of privacy and reliability if I understand correctly.

zulux 4 minutes ago | parent

Deployed wiring is indeed best. I will say wireless devices are often deployed while their wired counterparts sit there on the to-do list.

SecretDreams 25 minutes ago | parent

I am a simple man. I don't buy smart devices, mostly. Offline only is completely acceptable.

The connected home was an idealistic dream that has been made perverse by the Zucks and Elons of the world. It is not accessible for normal people and it might never be - at least, not without the blood sacrifice of your privacy.

thesuitonym 5 minutes ago | parent

I'm with you in theory but why on earth is anyone buying an air purifier that requires cloud connectivity at all?

criley2 2 minutes ago | parent

I don't mind the app functionality of my air purifier. I get a push notification when air quality degrades, and I can see data and charts of air quality over time. I can change the settings remotely, which is nice because I have a small child and keep the "lock" function set for the actual controls.

It's easier to setup and maintain schedules, routines, or more complex functionality.

It's certainly not critical functionality, but it's nice. Same with my laundry machine and dryer sending a push notification when the cycle ends. Unnecessary, but nice.

Aurornis 1 hour ago | parent

> The fan downloads its root CA cert over plain HTTP. It was always MitM-able.

The most fascinating part of this wave of LLM reverse engineering is seeing how many weird and poor choices were lying in plain sight.

Any number of people could have discovered and exploited this, but it’s tedious work. Most people who can do this are busy with their job and other things. Now LLMs enable people who understand these things to quickly get through the tedious parts, so they can do a lot more of this work in their free time than they could before.

eddieroger 4 minutes ago | parent

Similarly, how easy things are for more people to do. I'm certainly not advocating for pulling in a root CA over HTTP, but before LLMs could make this knowledge trivial, how many people would even think to look at that angle. It's democratizing in an interesting way.

analog8374 57 minutes ago | parent

We need a frontier to explore and exploit. Without it we turn inward, trying to chisel another 0.1% off each other.

jerkstate 44 minutes ago | parent

ChatGPT will allow you to do this interactively then ban you a few days later. Good luck OP.