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Comment by greyface- | Hacker News Reader

> Q: Why do attackers need to obtain video footage filled with the LED of the target device?

> A: Cryptanalysis requires a high sampling rate.

> By filling the frame with the LED, attackers exploit the rolling shutter to increase the number of measurements of the color/intensity of the LED by three orders of magnitude from the FPS rate (60 measurements per second) to the rolling shutter's speed (60K measurements per second in iPhone 13 Pro Max). A sampling rate of 60k can provide the needed sampling rate to attack functional IoT devices (smartphones, smartcards, TV streamers, etc.).

Using a single frame captured with rolling shutter as a 1-bit high-framerate video. Very cool technique!

View on HN

http://people.csail.mit.edu/mrub/VisualMic/ uses the rolling shutter to get audio from regular-framerate video of a bag of chips.

In that paper they use a "regular" high framerate camera. Those cameras are usually low resolution.

I guess what could be more interesting or practical: Low-res very high FPS, or very high resolution, and regular/high FPS (having more pixels would give you more sampling opportunities...).

In five years our budget-level Android phones will have both!

Reality check: what features do current budget-level Android phones have that weren't present on, say, a Galaxy S9 from 2018?

I do assume that you were talking in jest, but overestimations of technological progress are to much a pet peeve of mine that I had to bite. What will technology look like 40 years in the future? No idea. 40 years in the past we built a pretty cool maglev train (TR 06, best looking version of them all)

Then why was the train not put in service?

Why would you expect the train was not put in service ?

https://en.m.wikipedia.org/wiki/Transrapid

From the same link...

> The Emsland test facility was the only Transrapid track in Germany.[citation needed] It has been deactivated, and is scheduled to be disassembled.

GP was certainly referring to the Shanghai line, which feels much closer to put into service and to never put into service than one should reasonably consider possible at the same time.

I sure hope the Shanghai line is not using 40 year old technology.

Probably didn't see much modernization in the 20 years since it was opened. The trains in operation are two prototype iterations more advanced than the TR 06 from 1983, but differences to the TR 08 aren't bigger than differences between variations of the same high speed trains stools to different countries.

I was talking about the German Transrapid 06 but probably misread... will double check next time, sorry.

Plenty of reasons. Biggest one is diminishing returns of increasing top speed in ground transport. (or any transport - when was the last time a new airliner was advertised as being faster than its predecessor?)

I compared [0] the Galaxy S9+ to the Google Pixel 6a, the first Google result I got for "budget Android phone 2023" on [1]. Obviously you can go further downmarket.

As far as I can tell, they're comparable in features and specs. The Galaxy has better screen resolution, the Pixel has better networking... The only thing I could identify as a feature missing in the Galaxy is "dual LED flash" which was obviously technically possible in 2018.

So yeah, I was being a bit facetious. Considering the lifetime of phones, it probably takes 10 years rather than 5 for a farmer in Kenya to have a more powerful phone than a Bay Area programmer does today.

[0] https://m.gsmarena.com/compare.php3?idPhone1=8967&idPhone2=1...

[1] https://www.androidpolice.com/best-budget-android-phones/

The Pixel Xa phones are in no sense budget. A new budget phone is less than $100, and many of these are still sold in affluent countries.

https://www.gsmarena.com/motorola_moto_e7-10511.php

https://www.gsmarena.com/oppo_a57s-11835.php

At present that means ~2/4GB RAM, 4G, slow CPU, 50mpix, very laggy camera processing (because pixels are a metric buyers don't understand), slow storage I/O, no fancy comms like SOS beacons, UWB, limited security (no separate security enclave chip), and of course, old android and slow patching that stops quickly.

But you can at least get a headphone jack on the E7.

I'm not super convinced about that. The (raw) quality in the phones sensors hasn't climbed as quickly as on dedicated cameras this last years. The secret sauce for today's phone's cameras is a lot of processin, and if you get an unprocessed photo from a current day phone-size sensor is almost as bad as one from yeeears ago.

And that's OK for regular photos, but I guess is not that good if you want to do image or signal processing and your data has already gone through some other processing and a "IA".

Raw sensor size in cell phones has massively increased compared to years ago, and improvements in sensor technology (BSI, for instance) has improved performance of sensors of similar size. These did not exist before.

Obviously processing is getting more powerful, but I think you're discounting the improvements in the space. There's a few notable exceptions (e.g., Pixel phones used the same kinda crappy sensor for many generations), but largely people keep using the newer, better sensor on flagship devices.

They use both.

This is very cool, but I can't understand how 60khz is enough resolution to usefully discern what would be happening inside a CPU, etc, that's running way faster than that? (Disclaimer: I can't read the article as it says "browser not supported".)

EDIT - Answered here: https://news.ycombinator.com/item?id=36332352

The idea is that in typical assymetric cryptosystem you do some variant of bitwise exponentation of “large values” (ie. slow) and both the power envelope and timing is directly related to individual bit values of the private key. This trivially works for RSA and also anything involving integer-like groups and then even for “classic” ECC, things like 25519 are intentionally designed to mitigate this kind of side channel.

enhance!

Reply on news.ycombinator.com