
or obscure the watermarks. This attack assumes a
stronger adversary than other types. To test our mod-
ified algorithm’s robustness, we generated two ver-
sions of the same dataset with different watermarks
and parameters (e.g., f
Barker
, dwt, mult). Our results
show that recovering the watermark or parameters is
difficult, as each one affects the data in a random,
uncorrelated way. Additionally, the use of a high-
entropy secret in generating w prevents the watermark
from being guessed. We will explore more advanced
collusion scenarios involving multiple copies.
5 DISCUSSION
Our imperceptibility tests show that changing f
bin
and
DWT level has minimal impact on output quality, sug-
gesting that a fixed DWT level is not essential for time
series data as it is common in audio watermarking.
For cropping attacks, the use of Barker codes proved
partially effective: with f
Barker
= 600, only one intact
block of 600 values is needed to fully recover the wa-
termark. This outperforms the method in (Attari and
A. Shirazi, 2018), which handles only a 200-sample
removal at the beginning of an audio signal. While
our method remains robust when up to 10% of data is
affected at random, performance drops beyond that.
Unlike in Attari et al.’s audio watermarking, us-
ing a Fibonacci mult of 1.618 in time series data in-
creased perceptibility and had limited robustness ben-
efits. A smaller mult (1.2) worked better, likely due
to the lower value spread in time series compared to
audio. While we use standard distortion metrics, dis-
tortion is highly use-case dependent and influenced
by attack types. As noted in (
˙
Is¸ler et al., 2024), opti-
mizing and generalizing distortion remains a complex
challenge, which we plan to explore further both the-
oretically and experimentally.
6 FUTURE WORK AND
CONCLUSION
We proposed a novel technique to watermark non-
medical time series by adapting an audio watermark-
ing technique (Attari and A. Shirazi, 2018). We
experimentally showed that our approach is robust
against cropping, scaling, and small-scale randomly
sampled attacks. We also evaluated the effect of wa-
termarking on data utility (imperceptibility) using dif-
ferent multiplication rates. Determining the optimal
parameters for a given time-series dataset is an inter-
esting future direction.
ACKNOWLEDGEMENTS
This paper is supported by the European Union’s
Horizon Europe research and innovation program un-
der grant agreement No. 101094901, the Septon
and 101168490, the Recitals Projects. Devris¸
˙
Is¸ler
was supported by the European Union’s HORIZON
project DataBri-X (101070069).
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