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MS Paint and Photos inivisibly watermark even locally generated output with GUID
Reverse engineering shows Microsoft Paint and Photos use local Stable Diffusion models while remotely moderating prompts and receiving server-issued GUIDs. The GUID is embedded as an invisible pixel watermark and duplicated in signed C2PA metadata; local generation still requires connectivity. Paint enforces watermarking more strictly than Photos, and provenance-preserving export formats exclude BMP, raising privacy and transparency questions.