Supporting Large Scale Communication Systems on Infrastructureless Networks Composed of Commodity Mobile Devices: Practicality, Scalability, and Security.

security;censorship;Infrastructureless networks;delay tolerant networks;the Sybil attack;human mobility and contacts;Computer Science;Electrical Engineering;Engineering;Electrical Engineering: Systems

Liu, YueWallach, Dan S ;

University of Michigan

关键词: security;    censorship;    Infrastructureless networks;    delay tolerant networks;    the Sybil attack;    human mobility and contacts;    Computer Science;    Electrical Engineering;    Engineering;    Electrical Engineering: Systems;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/120779/liuyue_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Infrastructureless Delay Tolerant Networks (DTNs) composed ofcommodity mobile devices have the potential to support communicationapplications resistant to blocking and censorship, as well as certaintypes of surveillance. In this thesis we study the utility,practicality, robustness, and security of these networks.We collected two sets of wireless connectivity traces of commoditymobile devices with different granularity and scales.The first dataset is collected through active installation ofmeasurement software on volunteer users;; own smartphones, involving 111 users of a DTN microblogging application that we developed. The second dataset is collected through passive observation of WiFi associationevents on a university campus, involving 119,055 mobile devices.Simulation results show consistent message delivery performances of thetwo datasets. Using an epidemic flooding protocol, the large networkachieves an average delivery rate of 0.71 in 24 hours and a median delivery delay of 10.9 hours. We show that this performance is appropriate for sharing information that is not time sensitive, e.g., blogs and photos. We also show that using an energy efficient variant of the epidemic flooding protocol, even the large network can support text messages while only consuming 13.7% of a typical smartphone battery in 14 hours.We found that the network delivery rate and delay are robust todenial-of-service and censorship attacks. Attacks that randomly remove90% of the network participants only reduce delivery rates by less than 10%.Even when subjected to targeted attacks, the network suffered a less than 10% decrease in delivery rate when 40% of its participants were removed.Although structurally robust, the openness of the proposed networkintroduces numerous security concerns. The Sybil attack, inwhich a malicious node poses as many identities in order to gaindisproportionate influence, is especially dangerous as it breaks the assumption underlying majority voting. Many defenses based on spatial variability of wireless channels exist, and we extend them to be practical for ad hoc networks of commodity 802.11 devices without mutual trust.We present the Mason test, which uses two efficient methods for separating valid channel measurement results of behaving nodes from those falsified by malicious participants.