SemField: A Simple, Linear, Continuous, yet Robust Semantic Watermark
SEMFIELD introduces a simple, training-free semantic watermark that embeds a continuous signal into sentence embeddings for robust document detection. It works by iteratively selecting sentences that best align with a secret Gaussian direction determined by a key, allowing for reliable detection even against paraphrasing and structural tampering. SEMFIELD-PL enhances this by first optimizing the orientation based on the initial sentence.