Text Watermarking

There’s been a lot of discussion recently about the GenAI giants “watermarking” their output, which to say hiding some data in it so you can tell that it’s been generated by ChatGPT or Gemini or Claude or whatever. The technology for watermarking images is as old as dirt, works as advertised, and doesn’t affect image quality. What’s new and controversial is a claim that they can watermark text output cheaply, simply, and without harming the quality of the text. I was curious how they did this so I dug in a bit. I’m mostly convinced that it works and is pretty clever. However, all the explanations are full of Computer-Science jargon that you need to be a professional developer to understand. So here’s an attempt to explain to non-insiders and then, indirectly, opinions on whether it’s good and what it means and doesn’t mean. How it works [To professionals: The following is vastly oversimplified but not, I think, misleading.] LLM software generates output a word at a time. The way it…