105 research outputs found
Copyright protection of scalar and multimedia sensor network data using digital watermarking
This thesis records the research on watermarking techniques to address the issue of copyright protection of the scalar data in WSNs and image data in WMSNs, in order to ensure that the proprietary information remains safe between the sensor nodes in both. The first objective is to develop LKR watermarking technique for the copyright protection of scalar data in WSNs. The second objective is to develop GPKR watermarking technique for copyright protection of image data in WMSN
Spread spectrum-based video watermarking algorithms for copyright protection
Merged with duplicate record 10026.1/2263 on 14.03.2017 by CS (TIS)Digital technologies know an unprecedented expansion in the last years. The consumer can
now benefit from hardware and software which was considered state-of-the-art several years
ago. The advantages offered by the digital technologies are major but the same digital
technology opens the door for unlimited piracy. Copying an analogue VCR tape was certainly
possible and relatively easy, in spite of various forms of protection, but due to the analogue
environment, the subsequent copies had an inherent loss in quality. This was a natural way of
limiting the multiple copying of a video material. With digital technology, this barrier
disappears, being possible to make as many copies as desired, without any loss in quality
whatsoever. Digital watermarking is one of the best available tools for fighting this threat.
The aim of the present work was to develop a digital watermarking system compliant with the
recommendations drawn by the EBU, for video broadcast monitoring. Since the watermark
can be inserted in either spatial domain or transform domain, this aspect was investigated and
led to the conclusion that wavelet transform is one of the best solutions available. Since
watermarking is not an easy task, especially considering the robustness under various attacks
several techniques were employed in order to increase the capacity/robustness of the system:
spread-spectrum and modulation techniques to cast the watermark, powerful error correction
to protect the mark, human visual models to insert a robust mark and to ensure its invisibility.
The combination of these methods led to a major improvement, but yet the system wasn't
robust to several important geometrical attacks. In order to achieve this last milestone, the
system uses two distinct watermarks: a spatial domain reference watermark and the main
watermark embedded in the wavelet domain. By using this reference watermark and techniques
specific to image registration, the system is able to determine the parameters of the attack and
revert it. Once the attack was reverted, the main watermark is recovered. The final result is a
high capacity, blind DWr-based video watermarking system, robust to a wide range of attacks.BBC Research & Developmen
Steganography and steganalysis: data hiding in Vorbis audio streams
The goal of the current work is to introduce ourselves in the world of steganography and steganalysis, centering our efforts in acoustic signals, a branch of steganography and steganalysis which has received much less attention than steganography and steganalysis for images. With this purpose in mind, it’s essential to get first a basic level of understanding of signal theory and the properties of the Human Auditory System, and we will dedicate ourselves to that aim during the first part of this work. Once established those basis, in the second part, we will obtain a precise image of the state of the art in steganographic and steganalytic sciences, from which we will be able to establish or deduce some good practices guides. With both previous subjects in mind, we will be able to create, design and implement a stego-system over Vorbis audio codec and, finally, as conclusion, analyze it using the principles studied during the first and second parts
AirCode: Unobtrusive Physical Tags for Digital Fabrication
We present AirCode, a technique that allows the user to tag physically
fabricated objects with given information. An AirCode tag consists of a group
of carefully designed air pockets placed beneath the object surface. These air
pockets are easily produced during the fabrication process of the object,
without any additional material or postprocessing. Meanwhile, the air pockets
affect only the scattering light transport under the surface, and thus are hard
to notice to our naked eyes. But, by using a computational imaging method, the
tags become detectable. We present a tool that automates the design of air
pockets for the user to encode information. AirCode system also allows the user
to retrieve the information from captured images via a robust decoding
algorithm. We demonstrate our tagging technique with applications for metadata
embedding, robotic grasping, as well as conveying object affordances.Comment: ACM UIST 2017 Technical Paper
TORKAMELEON. IMPROVING TOR’S CENSORSHIP RESISTANCE WITH K-ANONYMIZATION MEDIA MORPHING COVERT INPUT CHANNELS
Anonymity networks such as Tor and other related tools are powerful means of increas-
ing the anonymity and privacy of Internet users’ communications. Tor is currently the
most widely used solution by whistleblowers to disclose confidential information and
denounce censorship measures, including violations of civil rights, freedom of expres-
sion, or guarantees of free access to information. However, recent research studies have
shown that Tor is vulnerable to so-called powerful correlation attacks carried out by
global adversaries or collaborative Internet censorship parties. In the Tor ”arms race”
scenario, we can see that as new censorship, surveillance, and deep correlation tools have
been researched, new, improved solutions for preserving anonymity have also emerged.
In recent research proposals, unobservable encapsulation of IP packets in covert media
channels is one of the most promising defenses against such threat models. They leverage
WebRTC-based covert channels as a robust and practical approach against powerful traf-
fic correlation analysis. At the same time, these solutions are difficult to combat through
the traffic-blocking measures commonly used by censorship authorities.
In this dissertation, we propose TorKameleon, a censorship evasion solution de-
signed to protect Tor users with increased censorship resistance against powerful traffic
correlation attacks executed by global adversaries. The system is based on flexible K-
anonymization input circuits that can support TLS tunneling and WebRTC-based covert
channels before forwarding users’ original input traffic to the Tor network. Our goal
is to protect users from machine and deep learning correlation attacks between incom-
ing user traffic and observed traffic at different Tor network relays, such as middle and
egress relays. TorKameleon is the first system to implement a Tor pluggable transport
based on parameterizable TLS tunneling and WebRTC-based covert channels. We have
implemented the TorKameleon prototype and performed extensive validations to ob-
serve the correctness and experimental performance of the proposed solution in the Tor
environment. With these evaluations, we analyze the necessary tradeoffs between the
performance of the standard Tor network and the achieved effectiveness and performance
of TorKameleon, capable of preserving the required unobservability properties.Redes de anonimização como o Tor e soluções ou ferramentas semelhantes são meios
poderosos de aumentar a anonimidade e a privacidade das comunicações de utilizadores
da Internet . O Tor é atualmente a rede de anonimato mais utilizada por delatores para
divulgar informações confidenciais e denunciar medidas de censura tais como violações
de direitos civis e da liberdade de expressão, ou falhas nas garantias de livre acesso à
informação. No entanto, estudos recentes mostram que o Tor é vulnerável a adversários
globais ou a entidades que colaboram entre si para garantir a censura online. Neste
cenário competitivo e de jogo do “gato e do rato”, é possível verificar que à medida que
novas soluções de censura e vigilância são investigadas, novos sistemas melhorados para
a preservação de anonimato são também apresentados e refinados. O encapsulamento de
pacotes IP em túneis encapsulados em protocolos de media são uma das mais promissoras
soluções contra os novos modelos de ataque à anonimidade. Estas soluções alavancam
canais encobertos em protocolos de media baseados em WebRTC para resistir a poderosos
ataques de correlação de tráfego e a medidas de bloqueios normalmente usadas pelos
censores.
Nesta dissertação propomos o TorKameleon, uma solução desenhada para protoger
os utilizadores da rede Tor contra os mais recentes ataques de correlação feitos por um
modelo de adversário global. O sistema é baseado em estratégias de anonimização e
reencaminhamento do tráfego do utilizador através de K nós, utilizando também encap-
sulamento do tráfego em canais encobertos em túneis TLS ou WebRTC. O nosso objetivo
é proteger os utilizadores da rede Tor de ataques de correlação implementados através
de modelos de aprendizagem automática feitos entre o tráfego do utilizador que entra
na rede Tor e esse mesmo tráfego noutro segmento da rede, como por exemplo nos nós
de saída da rede. O TorKameleon é o primeiro sistema a implementar um Tor pluggable
transport parametrizável, baseado em túneis TLS ou em canais encobertos em protocolos
media. Implementamos um protótipo do sistema e realizamos uma extensa avalição expe-
rimental, inserindo a solução no ambiente da rede Tor. Com base nestas avaliações, anali-
zamos o tradeoff necessário entre a performance da rede Tor e a eficácia e a performance
obtida do TorKameleon, que garante as propriedades de preservação de anonimato
Application and Theory of Multimedia Signal Processing Using Machine Learning or Advanced Methods
This Special Issue is a book composed by collecting documents published through peer review on the research of various advanced technologies related to applications and theories of signal processing for multimedia systems using ML or advanced methods. Multimedia signals include image, video, audio, character recognition and optimization of communication channels for networks. The specific contents included in this book are data hiding, encryption, object detection, image classification, and character recognition. Academics and colleagues who are interested in these topics will find it interesting to read
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