Meta's Un-Stable Signature
Summary
The Hacker Factor analyzes Meta's Stable Signature watermark, arguing that claimed high accuracy is overstated due to dependent, biased output bits produced by a neural network. The post documents empirical tests showing clusters and repeated bit patterns, contradicting the assumption of independent 48-bit signatures and revealing significant false positives. It also critiques Google's SynthID and Adobe's TrustMark for similar independence assumptions and discusses regulatory implications for AI-based watermarking.