Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Hacking my “smart” toothbrush

kuenzi.dev

Post reply on HN
Print view View original

201–210 of 311 posts

Re: Hacking my “smart” toothbrush

#201

Post by JohnFen »

imp0cat wrote: post #79
aaronbrethorst wrote: post #63

Me, dumb: I change my Sonicare toothbrush head whenever it tells me to. I haven’t had a cavity in 8 years. You, a clever toothbrush-hacking genius: haha, the head is new again! This is neat, and I find the process of reverse engineering the Sonicare toothbrush fascinating, especially sniffing the NFC communication, but please change your toothbrush head every three months.

Yes, I realize I might be in the minority here, but isn't this actually great use of a smart device? Not having to keep track of brush head changes, awesome! One less thing to worry about, as the device is smart enough to tell me when it's time for a new one.

> isn't this actually great use of a smart device?

You don't need anything to tell you when it's time to change your toothbrush. You can tell by feeling it, or in the extreme, by just looking at it. There's no need to track anything.

Re: Hacking my “smart” toothbrush

#202

Post by bagels »

GoToRO wrote: post #128

Some facts: The tag is used to change the cleaning mode of the toothbrush automatically, to match the type of head you inserted. This makes very easy to change heads durring the same session. It is also used to register how long you used that head. A warning is shown when the head should be replaced. After a few warnings you will no longer get them, just the led to replace the head remains on. You can continue to bru…

Is it less effective because they slow the motors down or other trickery?

Re: Hacking my “smart” toothbrush

#204

Post by JohnFen »

fsflover wrote: post #174
ubermonkey wrote: post #173

All I know is that I absolutely never, ever, ever want my toothbrush to be "smart." We need to stop putting firmware in things that don't need firmware. Not everything needs a chip or intelligence. The rampant abuse of this kind of thing leads to shitty products and an uptick in electronic waste.

The chips are not a problem. Nonfree software is.

I disagree. For a toothbrush, the chips are a problem. If nothing else, manufacturing chips is very bad for the environment. We shouldn't be putting them in things that don't need them.

Re: Hacking my “smart” toothbrush

#205

Post by nuancebydefault »

tzs wrote: post #193
version_five wrote: post #158

Earlier quoted context omitted.

Engineer gonna engineer. Someone probably just had the time and misplaced passion for security, and when they explained at the weekly standup that they'd added lockout after three attempts, everybody just nodded and moved on.

This has long been a temptation for engineers. 40 years ago the textbook in the digital electronics class I took at Caltech had a chapter called "The Engineer as Dope Pusher" that talked about it. It gave as an example clothes dryers. The way most home clothes dryers working back then was you put the clothes in, you turn a dial on a timer to the number of minutes you want the dryer to run, and you press start. The me…

What do you mean by "reliable" wrt mechanical timers? I'm pretty sure the clothing dryer is a harsh environment for such a component (moisture and heat can easily cause corrosion and mechanical stress). Also, I guess timing gets less accurate over time. If there are rubbers preventing moisture from entering and oil from leaving, those rubbers will wear out.

Re: Hacking my “smart” toothbrush

#206

Post by nuancebydefault »

HarHarVeryFunny wrote: post #172
beefield wrote: post #126

Earlier quoted context omitted.

My pet peeve with bathroom scales is that it is impossible to find one that actually does what it claims and has accuracy of +-0.1kg. They do show the measurement to 0.1, but just shifting your weight differently can cause a difference of hundreds of grams. Does anyone knlw a scale that actually measures at 0.1kg accuracy?

After a ton of research I got an AccuCheck scale (~$30 on Amazon) which I'm happy with, and at least avoids most of the problems with modern digital scales. Clean minimalist look. Takes 3 AAA batteries. https://www.amazon.com/gp/product/B084SFRSBD/ It claims 0.1 lb accuracy, and seems pretty repeatable, but I haven't tested it for accuracy. These digital scales have multiple sensors (this one has 4), so it makes sens…

Luckily the exact science is an adding operation, ifi the sensors behave in a linear way, that is.

Re: Hacking my “smart” toothbrush

#207

Post by oehpr »

bagels wrote: post #202
GoToRO wrote: post #128

Some facts: The tag is used to change the cleaning mode of the toothbrush automatically, to match the type of head you inserted. This makes very easy to change heads durring the same session. It is also used to register how long you used that head. A warning is shown when the head should be replaced. After a few warnings you will no longer get them, just the led to replace the head remains on. You can continue to bru…

Is it less effective because they slow the motors down or other trickery?

This is a good question, but people are pretty sensitive to pitch changes, I think we would detect the motor slowing down.

It would be super easy to reveal as well. A family member with the same toothbrush, your head finishes first. Motor slows down, pitch goes down. Compare the two. Replace the old head, now they're the same. Scummy practice revealed. Scandal.

That said. I'm not totally sure on the mechanism that all electric toothbrushes use.

It's much harder to detect subtle amplitude changes.

Re: Hacking my “smart” toothbrush

#208

Post by CatWChainsaw »

stickfigure wrote: post #29
josephcsible wrote: post #26

Earlier quoted context omitted.

> Because it's a feature customers ask for? Aren't switches to temporarily bypass emissions controls in cars illegal, despite being a feature customers ask for? > What laws do you want written? I want all e-fuses to be banned, as well as any other means for manufacturers to permanently reduce, restrict, or remove functionality from products after they've been sold. > How "secure" am I allowed to make my product befor…

It's just a toothbrush.

So then why does it need ANY of this?

Re: Hacking my “smart” toothbrush

#209

Post by GoToRO »

bagels wrote: post #202
GoToRO wrote: post #128

Some facts: The tag is used to change the cleaning mode of the toothbrush automatically, to match the type of head you inserted. This makes very easy to change heads durring the same session. It is also used to register how long you used that head. A warning is shown when the head should be replaced. After a few warnings you will no longer get them, just the led to replace the head remains on. You can continue to bru…

Is it less effective because they slow the motors down or other trickery?

The bristles wear out. Their heads wear out but they also become soft from all the vibration so they dont't push as hard on the teeth. Also gunk might accumulate depending on how careful you rinse it.

Still better than a manual brush even in that state.

Re: Hacking my “smart” toothbrush

#210

Post by kuroguro »

netsec_burn wrote: post #57
nneonneo wrote: post #21

Earlier quoted context omitted.

I mean, even something as simple as `md5("very-long-secret-only-phillips-knows" + uid)[:4]` would be effectively unguessable. Not hard if you have the code for the firmware, but nigh-impossible otherwise.

The Sonicare app lets you download the latest firmware blob. So all you'd do is intercept it and find the function responsible for generating the password.

The app has the firmware embedded in it (resources/assets/firmware), not sure if it actually downloads a newer one or if it updates with the app. It does seem to be encrypted or compressed somehow tho.
Post reply on HN