$($a$)$Ruba sets up an onion service $($hosted at a local ISP$)$ to run a dissident news website. She posts news articles there $($using Tor to connect to the webserver hosting the site$)$ and people visit it to read these articles using the Tor browser to connect to the site. i$.$ Describe how someone might discover the URL $($e$.$g$.$ blahblah.onion$)$ of Ruba$$s onion site? $[1$ mark$]$ ii$.$ The government has discovered the URL to Ruba$$s onion service. They have launched timing attacks on it and have located the server hosting the onion site as well. They start to monitor all network traffic to and from the server hosting the onion site in the hope of locating $($i$.$e$.$ finding out the IP or the ISP$)$ the local dissidents that connect to this onion site. Can the government succeed in this objective? Explain your answer. Assume that the government can observe all traffic within their borders. $[5$ marks$]$ iii. The government finds the URL to Ruba$$s onion service and wants to shut it down. They don$$t know Ruba$$s identity, but they have a strong suspicion that the ISP hosting the onion service is inside the country. What could they do$$provide details of their steps$$in order to confirm that the onion service is inside the country? Assume that the government can observe and record all network traffic in the country but do not collude with the ISPs or hosting companies$$i$.$e$.$ they can not break into the server itself. $($Hint: Recall that Tor is only secure against a local adversary and weak against certain attacks.$)$ iv$.$ Pluggable Transports $($PTs$)$ were introduced by the Tor project to thwart the fingerprinting of the Tor protocol at the network level. PTs change the network protocol between the user and the first hop of the Tor network so that it looks different from the usual Tor protocol, by i$)$ changing the traffic patterns to look random or like another protocol or ii$)$ tunnel the traffic over another protocol. This defensive measure can help to prevent the censorship of the Tor network so that Tor clients are able to connect to the Tor network and use it to anonymise their network activity. Would connecting through a PT to Ruba$$s service have any effect $($i$.$e$.$ make it easier or harder$)$ on the government$$s ability to locate where it is hosted? In your response explain if it would or would not and explain why or why not. $($b$)$ Tor is useful as a tool to allow users to anonymously communicate with each other and with online services. i$)$ Explain how it allows users in regions with censorship to connect to censored websites hosted outside the region. Assume that the adversary is external to the communication channel $($i$.$e$.$ not one of the end$-$points$)$ and observing the network but is not able to manipulate any traffic. $[3$ marks$]$ ii$)$ Imagine that two users are communicating over Tor from within the same region where an adversary has complete observability of network traffic. Are these users linkable? Explain your reasoning with details of how. Recall what kind of adversary Tor is secure against and what kind of adversary it is not secure against. $($c$)$ The Tor network protects both users and websites. Describe what types of protection Tor provides to both of these groups.