🛡️Microsoft Paint's AI Watermark Hides a User-Linked ID
TL;DR
Images generated in Windows Paint and Photos carry an invisible 16-byte GUID that Microsoft's servers issue after moderating your prompt. Successive prompts are explicitly chained.
Images generated in Windows Paint and Photos carry an invisible 16-byte GUID that Microsoft's servers issue after moderating your prompt. Successive prompts are explicitly chained. Microsoft documented the watermark but not the identifier inside it.
Key Points
Vector 35 developer Xusheng Li reverse-engineered the C2PA manifest and published the finding
Paint sends the prompt to Microsoft for moderation, then encodes the returned GUID into the pixels of the locally generated image
Paint passes the previous promptGenerationId as lastPromptGenerationId, linking a user's requests in sequence
The invisible GUID is separate from the visible watermark option Microsoft offers users
The EU Code of Practice on Transparency requires machine-readable marking but does not require an identifier; Microsoft went further
Microsoft did not respond to a request for comment
Why It Matters
Compliance watermarking is quietly becoming attribution infrastructure. If provenance metadata can fingerprint the prompter, every AI transparency mandate needs a privacy review attached.
Quick Facts
Frequently Asked Questions
Why does this matter?
Compliance watermarking is quietly becoming attribution infrastructure. If provenance metadata can fingerprint the prompter, every AI transparency mandate needs a privacy review attached.
What happened?
Images generated in Windows Paint and Photos carry an invisible 16-byte GUID that Microsoft's servers issue after moderating your prompt. Successive prompts are explicitly chained.
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