Spymarks, Not Watermarks

Watermarks that spy on users are no mere watermarks

There’s a sneaky new evolution of the “watermark”, let’s call it — the spymark.

A watermark is a visible mark embedded in a physical or digital medium to verify authenticity or assert ownership.

A spymark is a hidden signal that makes your work traceable without your knowledge or consent.

Google SynthID is a spymark that embeds secret hidden signals “imperceptible to humans” (Google’s own words) into images, audio, text, and video. This signal can encode database identifiers that map to your identity. Your user records, full name, IP addresses, date of birth, physical addresses, political party affiliation, and more.

Google’s SynthID-Image paper reports that its SynthID-O variant can encode a 136-bit payload in a 512x512-pixel image. That is enough room for a 64-bit database identifier, with 72 bits left for error correction.