5 research outputs found
Voice biometric system security: Design and analysis of countermeasures for replay attacks.
PhD ThesisVoice biometric systems use automatic speaker veri cation (ASV) technology for
user authentication. Even if it is among the most convenient means of biometric
authentication, the robustness and security of ASV in the face of spoo ng attacks
(or presentation attacks) is of growing concern and is now well acknowledged
by the research community. A spoo ng attack involves illegitimate access to
personal data of a targeted user. Replay is among the simplest attacks to
mount | yet di cult to detect reliably and is the focus of this thesis.
This research focuses on the analysis and design of existing and novel countermeasures
for replay attack detection in ASV, organised in two major parts.
The rst part of the thesis investigates existing methods for spoo ng detection
from several perspectives. I rst study the generalisability of hand-crafted features
for replay detection that show promising results on synthetic speech detection.
I nd, however, that it is di cult to achieve similar levels of performance
due to the acoustically di erent problem under investigation. In addition, I show
how class-dependent cues in a benchmark dataset (ASVspoof 2017) can lead to
the manipulation of class predictions. I then analyse the performance of several
countermeasure models under varied replay attack conditions. I nd that it is
di cult to account for the e ects of various factors in a replay attack: acoustic
environment, playback device and recording device, and their interactions.
Subsequently, I developed and studied a convolutional neural network (CNN)
model that demonstrates comparable performance to the one that ranked rst
in the ASVspoof 2017 challenge. Here, the experiment analyses what the CNN
has learned for replay detection using a method from interpretable machine
learning. The ndings suggest that the model highly attends at the rst few
milliseconds of test recordings in order to make predictions. Then, I perform
an in-depth analysis of a benchmark dataset (ASVspoof 2017) for spoo ng detection
and demonstrate that any machine learning countermeasure model can
still exploit the artefacts I identi ed in this dataset.
The second part of the thesis studies the design of countermeasures for ASV,
focusing on model robustness and avoiding dataset biases. First, I proposed
an ensemble model combining shallow and deep machine learning methods for
spoo ng detection, and then demonstrate its e ectiveness on the latest benchmark
datasets (ASVspoof 2019). Next, I proposed the use of speech endpoint detection
for reliable and robust model predictions on the ASVspoof 2017 dataset.
For this, I created a publicly available collection of hand-annotations of speech
endpoints for the same dataset, and new benchmark results for both frame-based
and utterance-based countermeasures are also developed.
I then proposed spectral subband modelling using CNNs for replay detection.
My results indicate that models that learn subband-speci c information
substantially outperform models trained on complete spectrograms. Finally, I
proposed to use variational autoencoders | deep unsupervised generative models
| as an alternative backend for spoo ng detection and demonstrate encouraging
results when compared with the traditional Gaussian mixture mode
Electronic Evidence and Electronic Signatures
In this updated edition of the well-established practitioner text, Stephen Mason and Daniel Seng have brought together a team of experts in the field to provide an exhaustive treatment of electronic evidence and electronic signatures. This fifth edition continues to follow the tradition in English evidence text books by basing the text on the law of England and Wales, with appropriate citations of relevant case law and legislation from other jurisdictions. Stephen Mason (of the Middle Temple, Barrister) is a leading authority on electronic evidence and electronic signatures, having advised global corporations and governments on these topics. He is also the editor of International Electronic Evidence (British Institute of International and Comparative Law 2008), and he founded the innovative international open access journal Digital Evidence and Electronic Signatures Law Review in 2004. Daniel Seng (Associate Professor, National University of Singapore) is the Director of the Centre for Technology, Robotics, AI and the Law (TRAIL). He teaches and researches information technology law and evidence law. Daniel was previously a partner and head of the technology practice at Messrs Rajah & Tann. He is also an active consultant to the World Intellectual Property Organization, where he has researched, delivered papers and published monographs on copyright exceptions for academic institutions, music copyright in the Asia Pacific and the liability of Internet intermediaries
Electronic Evidence and Electronic Signatures
In this updated edition of the well-established practitioner text, Stephen Mason and Daniel Seng have brought together a team of experts in the field to provide an exhaustive treatment of electronic evidence and electronic signatures. This fifth edition continues to follow the tradition in English evidence text books by basing the text on the law of England and Wales, with appropriate citations of relevant case law and legislation from other jurisdictions.
Stephen Mason (of the Middle Temple, Barrister) is a leading authority on electronic evidence and electronic signatures, having advised global corporations and governments on these topics. He is also the editor of International Electronic Evidence, and he founded the innovative international open access journal Digital Evidence and Electronic Signatures Law Review in 2004.
Daniel Seng (Associate Professor, National University of Singapore) is the Director of the Centre for Technology, Robotics, AI and the Law (TRAIL). He teaches and researches information technology law and evidence law. Daniel was previously a partner and head of the technology practice at Messrs Rajah & Tann. He is also an active consultant to the World Intellectual Property Organization, where he has researched, delivered papers and published monographs on copyright exceptions for academic institutions, music copyright in the Asia Pacific and the liability of Internet intermediaries