Privacy

31981 readers

265 users here now

A place to discuss privacy and freedom in the digital world.

Privacy has become a very important issue in modern society, with companies and governments constantly abusing their power, more and more people are waking up to the importance of digital privacy.

In this community everyone is welcome to post links and discuss topics related to privacy.

Some Rules

Posting a link to a website containing tracking isn't great, if contents of the website are behind a paywall maybe copy them into the post
Don't promote proprietary software
Try to keep things on topic
If you have a question, please try searching for previous discussions, maybe it has already been answered
Reposts are fine, but should have at least a couple of weeks in between so that the post can reach a new audience
Be nice :)

Related communities

Chat rooms

[Matrix/Element]Dead
Discord

much thanks to @gary_host_laptop for the logo design :)

founded 5 years ago

MODERATORS

209

What's inside the QR code menu at this cafe? (peabee.substack.com)

submitted 1 month ago by poVoq to c/privacy@lemmy.ml

39 comments fedilink hide all child comments

you are viewing a single comment's thread
view the rest of the comments

[–] tiredofsametab@fedia.io 2 points 1 month ago (1 children)

I keep meaning to look more into how qr codes work. I always wondered if there were possible attack vectors if a bad actor exploited a flaw in the decoding of the image. My mind went to a zip bomb for no apparent reason (a tiny file that unzips to a massive amount of data on disk)

[–] ChaoticNeutralCzech@feddit.org 4 points 1 month ago* (last edited 1 month ago)

That is very decoder-specific. The most common QR reader apps are the Camera app on iPhones and Google Lens for Android so you'll want to target one of these (though Google Lens might be using cloud processing for that). There probably won't be any exploits in the image processing part but you obviously can write arbitrary data (including ASCII control characters such as CR, LF, null) into the "data" part of the QR code, as the encoding mode and data length is stored in the first 4+(n*8) bits of where data would be instead of null byte termination. Normally, the data is then right-padded with repeating 0xEC11 (or not) and then error correction follows (number of bytes in the error-correction part is defined by the size and ECC mode indicated in another region).