Detecting Diffusion-Generated Time Series Under Generator Shift

arXiv (Cornell University)

Abstract

The boundary between real and diffusion-generated time series is becoming increasingly difficult to draw, yet detection in this domain remains underexplored, especially when the generator is unknown. We compare white-box detection, which requires access to the generator, against black-box detection, which operates on the raw signal alone. The white-box approach, a reconstruction-based detector adapted from the image domain, works well in in-distribution but breaks down under generator shift: reconstruction-based detection in images succeeds because large generic generators provide a near-universal reconstruction prior, and no analogous generator exists for time series. In contrast, a simple off-the-shelf classifier used as a black-box detector performs remarkably well, achieving an average F1 of 79.2, a 22.1% relative improvement over the white-box approach, and a TPR@1%FPR of 57.2. Diffusion-generated time series detection is therefore not a direct transfer of the image domain problem. This work provides the first systematic exploration of white-box and black-box detection for diffusion-generated time series. We close by identifying several open and promising directions.

Authors 7

1. Zhi Wen Soi
2. Aditya Shankar

   Delft University of Technology

   Affiliation as printed

   Delft University of Technology Delft , Netherlands

3. Gert Lek

   University of Neuchâtel

   Affiliation as printed

   University of Neuchâtel Neuchâtel , Switzerland

4. Abele Mălan

   University of Neuchâtel

   Affiliation as printed

   University of Neuchâtel Neuchâtel , Switzerland

5. Daniel Neider

   TU Dortmund University

   Affiliation as printed

   TU Dortmund University Dortmund , Germany

6. Jian-Jia Chen Aachen

   TU Dortmund University · RWTH Aachen University

   Affiliation as printed

   RWTH Aachen University TU Dortmund University Aachen , Germany

7. Lydia Chen

   University of Neuchâtel · Delft University of Technology

   Affiliation as printed

   Delft University of Technology Neuchâtel , Switzerland

   University of Neuchâtel