Today I learned that many/most color laser printers layer an array of yellow microdots on top of documents 🔬
This Machine Identification Code https://en.wikipedia.org/wiki/Machine_Identification_Code encodes a print date and a serial number unique to the machine. It only became public knowledge in 2004, ~20 year after deployment 😑
The Technical University of Dresden released a tool 2 years ago to layer on _even more dots_ to render the MIC unreadable and aid whistleblowers publishing https://github.com/dfd-tud/deda ✊
Wow this stuff goes deeper
Now I wonder if my printer would let me copy a note - I won't try it though since it is internet connected...