A software developer claims to have reverse-engineered Google DeepMind’s SynthID system, showing how AI watermarks can be stripped from generated images or manually inserted into other works. A claim that, according to Google, isn’t true.

Has Google’s AI watermarking system been reverse-engineered?

Kind of, but not really. It’s complicated.

The developer, going by the username Aloshdenny, has open-sourced their work on GitHub and documented his process, claiming all it required was 200 Gemini-generated images, signal processing, and “way too much free time.”

“No neural networks. No proprietary access,” Aloshdenny said on Medium. “Turns out if you’re unemployed and average enough ‘pure black’ AI-generated images, every nonzero pixel is literally just the watermark staring back at you.”

SynthID is a near-invisible watermarking system that tags content generated by Google’s AI tools, embedding itself in the pixels of images at the point of creation. It was designed to be difficult to remove without degrading the image quality, and is used widely across the AI products offered by Google — everything spat out by models like Nano and Veo carries SynthID watermarks, and it’s even being applied to YouTube’s AI-generated creator clones.

Aloshdenny says he found the system to be “genuinely good engineering,” and was still unable to remove SynthID entirely in tests, instead relying on confusing SynthID decoders that try to read watermarked images.

The process used to crack the underlying mechanics of Google’s watermark is technically complex. Here’s a simplified explainer:

• Generate 200 entirely black or pure white images using Gemini. Enhance the contrast and saturation, and then denoise the saturation to expose the watermark patterns.
• Average the patterns together to find the magnitude and phase of the watermark signal at every frequency bin, per channel.
• Hunt for signs of these frequencies in images and partially remove them at the same angle at which they were inserted during generation.

“The fact that the best I could pull off was confuse the decoder enough that it gives up — not actually delete the thing — says a lot about how well it was designed,” says Aloshdenny. “It’s not perfect. But it’s not trying to be unbreakable. It’s trying to raise the cost of misuse high enough that most people don’t bother.”

At this point in time, it doesn’t appear that SynthID has been reverse-engineered to the point where it can be easily bypassed by the general public. Google also doesn’t believe it stands up to Aloshdenny’s claims.

“It is incorrect to say this tool can systematically remove SynthID watermarks,” Google spokesperson Myriam Khan told The Verge. “SynthID is a robust, effective watermarking tool for AI-generated content.”