457 research outputs found
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
SALWARE: Salutary Hardware to design Trusted IC.
Fabless semiconductor industries are facing the rise of design costs of integrated circuits. This rise is link to the technology change and the complexity increasing. It follows that integrated circuits have become targets of counterfeiting and theft. The SALWARE project aims to study (theoretically and experimentally) salutary hardware design in order to fight against theft, illegal cloning and counterfeiting of integrated circuits. Salutary hardware means an embedded hardware system, hardly detectable / circumvented, inserted in an integrated circuit or a virtual component (Intellectual Property), used to provide intellectual property information (eg watermarking or hardware license) and / or to remotely activate the circuit or IP after manufacture and during use
Robust video transmission using reversible watermarking techniques
This paper presents a novel error-resilient strategy which employs a reversible watermarking technique to protect the H.264/AVC video content. The proposed scheme adopts reversible watermarking to embed an error detection codeword within every Macro block (MB). The watermark is then extracted at the decoder and used to detect the corrupted MBs to be concealed. The proposed scheme further manages to recover the original video content after watermark extraction, thus providing no loss in video quality. The simulation results demonstrate that the proposed approach provides a substantial gain of up to 2.6 dB in Peak Signal-to-Noise Ratio (PSNR) relative to the standard with a minimal increase in complexity.peer-reviewe
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