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Hacking a Casio F-91W digital watch (2023)
- ComputerGuru 8mo agoI was captivated by the introduction but I only made it halfway through before I gave up. The random bolding and emphasizing of almost every other word really put me off. Also, even though I can see that it's clearly had a ton of human effort put into it, I got a lot of AI vibes from the writing.
- eresonance 8mo agoYeah I agree, I'm wondering if the author's primary language isn't English and they leaned heavily into AI to get this article together. Either way I found the subject cool but the writing hard to go through.
- FridayoLeary 8mo agolots of spelling mistakes which is odd for such a meticulously detailed article. I'm going for the theory he's not an english speaker. Op is wrong, it's one of the most interesting things i've seen here in a while and truly in the spirit of hn.
- ale42 8mo agoWell, everything in the article (names & places) seems to point out the author is Italian...
- blargthorwars 8mo agoYou’re absolutely correct! I was totally hooked by the intro—the kind that promises Forbidden Wisdom™—and then I made it about halfway before my attention quietly left the chat. The random bolding of almost every other word felt like getting yelled at by typography. I wasn’t reading anymore; I was flinching. And sure, I can tell there’s a ton of human effort in there, but the overall vibe? Very “AI but with a human supervisor.” Polished, eager, slightly over-explained, and aggressively formatted. I’m sure it’s useful. I just couldn’t finish.
- ThePowerOfFuet 8mo agoIt's leaking
- netsharc 8mo agoYeah, it's fucking goddamned excessive. Changing the CSS rule .jb { font-weight: 700; } to .jb { font-weight: 500; } got rid of all the bolded parts for me...
- ajot 8mo agoYou can read it in the Medium frontend scribe.rip, to avoid some Medium shenanigans. I do think bolding stays the same though, it seems to have lots of bolding. Weird style. https://scribe.rip/infosec-watchtower/how-i-hacked-casio-f-91w-digital-watch-892bd519bd15 https://scribe.rip/infosec-watchtower/how-i-hacked-casio-f-9...
- ComputerGuru 8mo agoNo, it doesn’t. This isn’t a Medium gripe (which sucks but isn’t to blame for once). Edit: this comment made sense before the post I replied to was edited to clarify that there is no material difference.
- layer8 8mo agoThe article was published in June 2023, which makes LLM use less likely for that kind of article.
- tguvot 8mo agohacking f-91w been very popular https://en.wikipedia.org/wiki/Casio_F-91W#Usage_in_terrorism https://en.wikipedia.org/wiki/Casio_F-91W#Usage_in_terrorism
- anthk 8mo agoThat's because the F91W was like Game Boy of watches. Or the Tetris under a 'Brick Game' branded cheap console. Every dad owned one. Reliable, cheap and damn long lasting.
- Findecanor 8mo agoThe world's most sold digital watch. Widely available since 1989. There are even multiple clones out there for a fraction of the price.
- throwaway81523 8mo agosensorwatch.net has been around many years.
- mrweasel 8mo agoThat still won't do contactless payments, at least I don't think so. It's a neat idea, to just move the chip. The final result isn't pretty, it would have been way cooler if the whole thing had fitted inside the watch, but there's not a lot of room in an F-91W. Maybe someone with more experience with antenna designs could find a way to use the backplate as part of the antenna.
- Guestmodinfo 8mo agoI want to put a better backlight in my A158W. Internally F-91W and A158W are same.
- scrapheap 8mo agoYou can get light spreader kits for the F91-W/A158W that replace the bit of plastic that sits behind the LCD for one that spreads the light from the LED far more evenly than the stock one. I recently fitted one on my F91-W and it certainly makes a difference, but it's not going to make the light brighter like some of the other LED mods people have done.
- Latitude7973 8mo agon-o-d-e (blogger) has published many mods for this watch, with videos included. They have great production quality, and the mods are easy enough to pull off. https://n-o-d-e.net/casio.html https://n-o-d-e.net/casio.html When I did this mod, I soldered the LED on its side, so that it shone directly onto the LCD. This made the watch face much brighter. On reflection, the similar variant of the watch with an EL display is vastly superior. The A168 is similar to the A158 you mentioned but with a better light.
- fellerts 8mo agoCool project. Tip: acetone will readily dissolve the plastic parts of the card leaving the antenna(s) and chip intact. I believe a few other people have made drop-in PCBs with NFC antennas. Here’s one: https://n-o-d-e.net/datarunner.html https://n-o-d-e.net/datarunner.html Also, no F-91W thread would be complete without a mention of the sensorwatch project: https://www.sensorwatch.net/ https://www.sensorwatch.net/
- dmaa 8mo agoThe dissolution in acetone is nicely demonstrated here https://youtu.be/NF4VJJKTjy8?t=835 https://youtu.be/NF4VJJKTjy8?t=835 The guy does it in order to be able to pay with a prosthetic eye.
- alejoar 8mo agoThis is hilarious!
- afandian 8mo agoI would like to encourage everyone to set some time aside, get comfy, and watch Bobby Fingers. His videos are extraordinary, special, things. I think making a giant Jeff Bezos boat would appeal most to this crowd, but I'd suggest watching them in order.
- piltdownman 8mo agoFor anybody wondering wth is with a guy sculpting dioramas about obscure celebrity misadventures - he was formerly half of the Hip-Hop Comedy Duo, Sketch Artists, and behemoth Irish podcasters 'The Rubberbandits'. Probably one of the greatest neo-dadaists and proponents of Aestheticism in Europe today. https://www.unitedartsclubdublin.com/post/bobby-fingers-the-poetry-of-a-prosthetist https://www.unitedartsclubdublin.com/post/bobby-fingers-the-... Some might even know them without realising it - their incredibly provocative Richard D. James-esque 'Dad's Best Friend', a sonic assault about isolation and toxic masculinity, was featured prominently in the Trainspotting Sequel, "T2" https://youtu.be/iYgPznBrjiA https://youtu.be/iYgPznBrjiA
- NetMageSCW 8mo agoI’ve been doing Apple Pay without issue with the phone since it started, and doing it without authentication since the Apple Watch came out. The (very) few issues wouldn’t be fixed by putting the system in a different case. Seems like a lot of work for nothing.
- netsharc 8mo agoI watch a YouTube series of 2 guys who restored a classic Mini car (putting the running gear of another car into it, adding bells and whistles and more bells and whistles). They've been going at it 12 years, when they could've just bought a modern car. Seems like a lot of work for nothing.
- jansper39 8mo agoThis is Hacker News is it not? I'm sure if this guy wanted to buy an Apple watch, he could have just done that.
- camillomiller 8mo agoAnother good effort and well intentioned piece ruined by soulless AI writing. If English is not your primary language, it’s ok. Rather write with mistakes and quirks: it would still feel more human and readable than a draft flattened and weakened by using chatGPT
- tomaytotomato 8mo agoI think going by the timestamp of the article and checking the article on a couple of AI detectors, that this article has a low probability of being written by GPT. More than likely just translation anomalies from Italian to English.
- mschuster91 8mo agoThe problem with this approach is, every once in a while - I think the bank sets the limit - the card will not accept any NFC transactions at all until a physical confirm-with-pin transaction is made. That frankenstein'd chip... no way it can ever be assembled back into a "holder" card without risking everything breaking.
- taneliv 8mo agoYes, at least according to the information I have, the card issuer sets the limit. It's not clear to me if the chip actually has to be physically slotted in for reading it, though. Can the confirm-with-pin step be done without contact, using NFC feature?
- rubslopes 8mo agoFor me, it'll randomly ask for the pin code as OP reported, but card insertion is never required.
- mschuster91 8mo agoAgain I guess it depends on the bank. I have to go through the full insert physically so that the contactless-count gets reset. And of course, it always happens when buying a pack of smokes or a drink at a vending machine that does not have a PIN pad -.-
- amelius 8mo agoNice work but a pity they will have to redo it once their payment card expires.
- bytesandbits 8mo agothat was very well documented! great job
- forinti 8mo agoThese F-91W projects inspired me to buy one, but I found it to be so small (and I don't have a particulary big wrist). So I gave it to my 12 year old and bought a W-217H, which is almost identical but larger.
- xdavidhu 8mo agoI wish there were a way to put the chip & antenna inside (or behind?) the watch casing. While this is really impressive, putting something in front of the faceplate breaks the great F-91W look and feel for me.
- jonhohle 8mo agoProjects like ollee Watch seem to be able to stash it behind the front crystal or underneath the LCD.
- xdavidhu 8mo agoOllee does that by replacing the original PCB. In this project the movement is kept original. I recall the blog n-o-d-e did successfully put an NFC chip inside while also retaining the default PCB, so there is at least some free space in the case... https://n-o-d-e.net/casio.html https://n-o-d-e.net/casio.html (0:56)
- jqpabc123 8mo agoOr just forget the watch and casing and build an add-on to the strap to hold the NFC chip. This should work with any watch strap that isn't metal. Similar project I did to carry a microSD memory card. https://www.thingiverse.com/thing:6784665 https://www.thingiverse.com/thing:6784665
- simonmorley 8mo agoI enjoyed reading this, a lot. Really not really sure why everyone’s more bothered by the use of ai to help write it. But you can’t please everyone.
- deadbabe 8mo agoI don’t know why Casio doesn’t just do something like this themselves, I’d buy it. Don’t need a super smart watch but do like contactless payment with a wrist.
- jqpabc123 8mo agoApparently, Casio fails to recognize that nowadays, most people don't really need a watch for timekeeping because they carry a smartphone that does time perfectly well. I wear a cheap $5 Chinese made watch only because I use it to carry a backup of all my crucial data with me at all times, even in the shower. If something goes bump in the night, my data is always with me so all I need to worry about is my own personal safety. https://www.thingiverse.com/thing:6784665 https://www.thingiverse.com/thing:6784665 Casio could easily and cheaply add this to their watches and instantly make them much more desirable in my opinion.
- deadbabe 8mo agoIs your data encrypted at rest? Someone could kill you and steal it very easily.
- speedgoose 8mo agoIf the threat model includes murder, they can get my encrypted data anyway. See XKCD #538: https://xkcd.com/538/ https://xkcd.com/538/
- jqpabc123 8mo agoThe watch itself is certainly nothing anyone would kill me for <g>. But yes, the entire microSD card is encrypted using BitLocker in case it happens to be lost or otherwise falls into the wrong hands. My will contains the decrypt password. If you think about it, my data is as safe as I am --- if not safer. The authorities aren't going to spend any effort to recover a memory card --- but they will to recover a body with a memory card attached.. Since this is always with me, it serves as the off-site copy in my 3-2-1 backup plan. https://www.backblaze.com/blog/the-3-2-1-backup-strategy/ https://www.backblaze.com/blog/the-3-2-1-backup-strategy/
- t1234s 8mo agoF-91W backlight fix: https://www.etsy.com/listing/1448973768/back-light-spreader-for-casio-f-91w-a https://www.etsy.com/listing/1448973768/back-light-spreader-...
- askl 8mo ago> I thought it would be nice not to have to take out my credit/debit card from the wallet or my mobile phone from the pocket to pay, but instead, to bring the watch closer to the PoS and just pay with a pinch of modern-day magic . I don't know, every time I see someone paying with their watch it looks super awkward when they have to twist their arm so the watch gets close enough to the reader. Most of the time they are holding their phone in their other hand which makes the whole thing extra silly and unnecessary. I still think this is a pretty cool project.
- timerol 8mo agoThis is a really cool hack, and I wish I could pay for things with a dumb watch. It's just the right level of useful and silly to be up my alley. But the article, as others have mentioned, is a little off. The author did not "invent" the guess-and-check method for verifying resonance. That's been a staple of radio since the beginning, which is why original tuner dials were actually variable capacitors > Therefore, an ideal antenna should consist of a 22.12 metre long wire, but by convention fractions of λ-lambda (λ/2, λ/4, λ/8, λ/16, etc.) are opportunely chosen. This sentence is confused enough to be incorrect. λ/2 is generally preferred as an antenna length (standard dipole configuration) because it will resonate at the appropriate frequency with desirable standing wave characteristics (current maximum and zero voltage at input, voltage maximum and current minimum at ends). λ/4 can be used as a half-dipole, but it requires a ground plane to resonate properly. There are also arguments to be made for a 5λ/8 antenna, but none that I'm aware of for λ/8 or λ/16. In practice for small antennas, physical length and electrical length are only tenuously related, so it's a matter of creating a circuit that acts like an antenna of the chosen length.
- x-n2o 8mo agoIs there a short but decent RF/antenna crash course? I’m fascinated by the topic — though the prospect of going through a textbook and revisiting the physics rabbit hole gives me massive anxiety (it always ends up recursing to philosophy).
- conroydave 8mo agoi love this and its something i had always wanted to try. I am actually kind of ticket off at chatgpt as i asked it about 6 months ago how something like this work and it told me it physically wasnt possible. maybe i need to improve my prompting.
- puzzlingcaptcha 8mo agoIs NanoVNA still the best entry-level tool in 2026?
- achayala 8mo agoWell documented!. I hope you don't lose your watch hehe
- jqpabc123 8mo agoInteresting --- but it looks like a lot of unnecessary work to me. Forget modifying the watch itself. Instead, build a strap add-on to hold the NFC payment chip and antenna. Here is a project where I did something similar to carry a microSD memory card. https://www.thingiverse.com/thing:6784665 https://www.thingiverse.com/thing:6784665
- mrb 8mo agoNothing was unnecessary since the goal was having fun & learning.
- throwaway293892 8mo agoDoing so gives you free room and board at Guantanamo Bay. If you ever wanted to visit Cuba ... https://www.theguardian.com/world/2011/apr/25/guantanamo-files-casio-wristwatch-alqaida https://www.theguardian.com/world/2011/apr/25/guantanamo-fil...
- ekjhgkejhgk 8mo agoCurious, I've had one of those watches for years and never got caught. OR perhaps your meme is out of date.
- 0xbeefcab 8mo agoQuick correction to the opening paragraph: You actually can use tap-to-pay without unlocking your phone (for iOS at least) when paying for a public transit fare. Theres a setting called transit mode or express or something. Once enabled, you just hold your phone up and it works without authenticating