Device Fingerprinting & Serial Numbers
Most users worry about where a photo was taken. Few worry about what took the photo. This oversight allows researchers to link anonymous identities to physical hardware.
Section 1: The Unique Identifier
High-end cameras (DSLRs/Mirrorless) and some smartphones inject a unique hardware serial number into the metadata. This is often hidden deep within the `MakerNote` tag—a proprietary section of the EXIF data used by manufacturers. This number is immutable and unique to that specific physical device.
Section 2: The Linkage
This creates a vulnerability known as "Linkage." If you post a photo on a pseudonym account (e.g., a whistleblower account) and another photo on your personal Facebook page using the same camera, the serial numbers match.
Researchers and algorithms can scrape the web for this specific serial number. Once a match is found, the anonymity of the pseudonym is instantly compromised. The hardware itself betrays you.
Section 3: The Use Case
This is not theoretical. It is a standard technique in forensics.
- Journalists: Protecting sources who send images.
- Activists: Documenting events without revealing their identity.
- Whistleblowers: Leaking documents without leaving a hardware trail.
Section 4: The Hygiene
Standard "Remove Properties" tools in Windows often fail to scrub the proprietary `MakerNote` section. To ensure these deep identifiers are removed, the file must be re-processed.
A privacy focused image editor rebuilds the image container from scratch, discarding all non-standard and proprietary tags. This breaks the chain of custody, ensuring your hardware cannot be fingerprinted across the web.