[wstuartcl]

I worked on something very similar, my version also mutated punctuation and common phrases/words with synonyms and sentence re-ordering. Instead of steganography the purpose was to create identifiable mutations in text acting as a canary to tie disclosures back to specific recipients. Each party receiving a confidential document had slight mutations unique to their own document and given a copy/paste from a fairly small fragment(s) could be used to identify the owner of the version.

[matt_the_bass]

This seems like a useful tool. Is it a product?

[wstuartcl]

No Sorry it was constructed to catch an employee leaking confidential company information to media. I do not know how you could make this into a product and still maintain its reliability -- the more widely known the mutations are the easier it would be to mitigate the watermarking.