● Covered by 2 sources · 2 reportsMedium impact2 neutral
MS Paint and Photos embed invisible GUID watermarks in AI-generated images
Key points
- Paint and Photos send AI prompts to a remote server for moderation.
- The server returns a GUID, which is embedded as an invisible watermark.
- Local AI image generation on Copilot+ PCs still uses remote prompt moderation.
- Invisible watermarking is separate from visible watermark settings.
- Developer Xusheng Li discovered the invisible GUID watermark.
- Invisible watermarking also attaches C2PA Content Credentials.
- Li found four model files in the app path for local processing.
- One local file was ONNX-like, three were encrypted ONNX-like files.
- Li uncovered watermarker.dll during his investigation.
Invisible Watermarking in Microsoft Apps
Microsoft Paint and Photos applications are embedding invisible watermarks into AI-generated images. This occurs even when images are generated locally, as the prompt itself is sent to a remote server for moderation. The server returns a Globally Unique Identifier (GUID) which is then embedded into the image.
Mechanism of Watermarking
The process involves sending the user's prompt to a remote server for content moderation. Upon approval, the server provides a GUID that is then incorporated into the generated image as an invisible watermark. This mechanism operates independently of any visible watermark settings within the applications.
Local Generation, Remote Moderation
While Microsoft has shipped local AI models within Windows for applications like Paint, particularly for Copilot+ PCs, the prompt moderation step remains a remote process. This means that even if the image generation itself happens on the user's device, the interaction with a remote server for moderation and GUID assignment still occurs.
C2PA Metadata and File Formats
Microsoft has stated that Paint adds C2PA metadata to AI-generated images. Saving these images is restricted to C2PA-preserving formats such as PNG, JPEG, GIF, and the proprietary .paint format, ensuring the embedded GUID and other metadata persist within the file.
Updates
- Developer Xusheng Li discovered the invisible GUID watermark.
- Invisible watermarking also attaches C2PA Content Credentials.
- Li found four model files in the app path for local processing.
- One local file was ONNX-like, three were encrypted ONNX-like files.
- Li uncovered watermarker.dll during his investigation.
✨ This summary was generated by AI from the outlets' reporting listed below. It is not independently verified and may contain errors — check the original sources. How BrevFeed works →
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How outlets covered it
Developer Xusheng Li discovered that Microsoft's Paint and Photos applications embed an invisible GUID watermark into AI-generated images, in addition to visible Copilot logos. This mandatory watermarking process, which also attaches C2PA Content Credentials, identifies AI-created content and requires prompts to be sent to Microsoft servers for moderation even during local generation. This development matters as it reveals Microsoft's method for content provenance and moderation for AI-generated media within its popular applications.
Microsoft's Paint and Photos applications invisibly watermark AI-generated images, even those created locally, with a GUID after sending prompts to a remote server for moderation. This occurs regardless of visible watermark settings and applies to images saved in C2PA-preserving formats like PNG, JPEG, GIF, and .paint. The practice raises questions about user privacy and the traceability of AI-generated content.