Cryptographer Matthew Green asks if Apple Reference Image embeds your phone ID in signed photos

matthew_d_green · x · 2026-09-10

Johns Hopkins cryptographer Matthew Green raises a privacy question: is Apple's Reference Image mechanism privacy-preserving, or does every signed photo now contain the user's phone ID?

The post is a question without an answer or official response yet, but targets a potential device-level tracking risk in photo signing.

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