On a related topic, it would be fun to embed the EURion constellation[0] into random things just so it results in difficult to trace side-effects. For example wear a t-shirt with it printed on, if someone tried to edit CCTV footage or a photo of you, it might error out.

[0] https://en.wikipedia.org/wiki/EURion_constellation

EURion only works on flat services (photocopiers and scanners). Photoshop detects currency based on a Digimarc watermark, which you can't generate without paying a licensing fee.

> Photoshop detects currency based on a Digimarc watermark, which you can't generate without paying a licensing fee.

You can't generate your own without paying a licensing fee. Nothing[§] prevents you from extracting existing watermarks and applying them to other things. This is called a copy attack. There are mitigations[1] but I believe they are not practical for banknotes. I've been told by a Digimarc representative in private conversation about the mentioned paper, that "The Digimarc for Images solution does not utilize the exact functionality described in the paper [..]". This was in 2011, I don't know if things have changed.

[§] Ok, nothing technical at least; legally it's a different matter...

[1] https://www.digimarc.com/docs/default-source/technology-reso...

The current research in to the Digimarc currency watermark has determined an absolute minimal test case [1], however no one has discovered the exact watermarking mechanism. I was speaking in absolutes because we can't do a copy attack without knowing what features to extract.

Someone has enumerated all the detected regions on the 20 pound note [2] if you'd like to take a stab at it!

1. https://murdoch.is/projects/currency/cropped.png

2. https://murdoch.is/projects/currency/small_crops.png

I don't know anything about Digimarc, but it looks like this tool may allow you to create watermarks as other people using the official digimarc software https://github.com/flarn2006/DigimarcPIN/

> Photoshop detects currency based on a Digimarc watermark, which you can't generate without paying a licensing fee.

Sounds like a challenge for hackers. :-)

I'm sure at least one person in the world has reverse-engineered the algorithm, and it might be quite simple, but the legal implications prevent its publication. If anything, it would be more likely to be on the dark web.

I saw these a while ago:

https://www.zazzle.com/eurion_constellation_t_shirt-23550976...

The EURion is only what outdated software uses; there's a new scheme based on invisible digital watermarking.

I first thought of that after I read Gibson’s Spook Country. Never tried it out though.

This is super dystopian.