Natural Language Watermarking with ChatGPT

Digital watermarks for texts come in numerous forms. The text itself, but also its appearance, i.e. font, letter spacing or line spacing, can be modified. Here, we present an approach that marks the text itself by introducing changes to the written words. For this, numerous methods are known, such as change from active to passive, modulation of sentence lengths or replacements with synonyms. We use ChatGPT to supplement existing texts with suggestions for synonymous formulations. We also look at evaluating the transparency of the marked texts with the help of ChatGPT.