In this lesson, we present the censor model and survey result of the censorship resistance system paper presented by [inaudible] et al in [inaudible] security and privacy 2016. Their approach and key contribution are discussed. The rise of Censorship Resistance System. The Censorship Resistance System attract a lot of attention due to its high impact usage in allowing the organizer of the Arab Spring to test, to utilize a social networking tools, to organize an activity effectively in such a large scale. It was used throughout the world, the CRS was mostly successful in achieving its goal even under the censor active effort in trying to disrupt its access and hosted documents. There are more than 60 country engage in some form of censorship. The Censorship Resistance System are developed to both provide unfettered access to information and to protect the integrity and availability of published documents. Know that for certain more positive cases, the censor may try to block offensive documents or remove malicious code. Here, we show a censor model where a code of a censor are to first, corrupt documents hosted on a publisher server or reside on a users. Second, sniff the packets and check who are requesting, or relaying, or posting certain data. Third, block the access of sensitive data, either add users, publishers, server, or on the network link. It is harder to corrupt documents since it's required to break in to the users or servers on the publisher. It is easier to block and filter traffics at entry point in the network owned by a censor. At the same time, it is harder to monitor or trace traffic along or pass on the internet, where it is out of your own control and influence. Also, there are way too many node and network to watch. As a censorship resistance system, the tone network encrypt data with different key on entry, the middle, the exit nodes, along its [inaudible] pass in order to avoid being blocked or traced by the censors. The tone network make it harder for the censor to guess who are the users. The hidden server capability provided by tool allows the publisher to be invisible to the censor. What are common techniques against corrupting document by the censor? If you think about the basic service, you know the integrity type of techniques we're dealing with at. Based on the survey, the also fun there are diverse censorship mechanisms across different jurisdictions and their evolution over time, and they are evolving over time. There is no single censor resistance system that is optimal for all censor. The literature survey also show lack of broad perspective on censor capability. Approaches on censor resistance and they are lack of analysis on the overarching trend, and the security gap in the field. The goal of their proposed censorship research are to characterize knowledge and techniques used by the censor and censorship resistance system. The other goal is to find common threads in censorship resistance system. The third, is to evaluate these threads. Fourth, relate these threads to censors attacking capability. Fifth, identify a list of research gaps, intended to provide a unified thread model with the same set of metric for evaluating the performance of the censor resistance system. There also surveyed 73 censorship resisting systems. From the effort, they develop a single, comprehensive model for off censor capability, extracted out the censor resisting system scheme based on the recurring theme and underlying concept. They're defined CRS in terms of properties of security, such as an observability realized by obfuscating technique, and a block ability property, integrity property and availability property. For privacy, they consider anonymity and deniability, and they also consider performance and deployability. There applies a framework for evaluating several CRS scheme, then discuss the overarching research gaps and challenging for future research.