Zero-Width Characters: Invisibly fingerprinting text
This blog post (from colleagues) covers the ideas in a little more detail <a href="http://blog.fastforwardlabs.com/2017/06/23/fingerprinting-documents-with-steganography.html" rel="nofollow">http://blog.fastforwardlabs.com/2017/06/23/fingerprinting-do...</a> and comes with proof-of-concept code <a href="https://github.com/fastforwardlabs/steganos" rel="nofollow">https://github.com/fastforwardlabs/steganos</a>.