Browsing by Subject "Anonymity"
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Item Anonymity in Bitcoin and Bitmessage(2017-05) Krawisz, Daniel Gregory; Garg, Vijay K. (Vijay Kumar), 1963-This report describes two projects created by the author which are based on ideas which originate from the Bitcoin community. The first, bmd, is a re-implementation of the Bitmessage protocol in go. Bitmessage is an anonymous and secure messaging system invented by Jonathan Warren, who was inspired by the design of Bitcoin's p2p network. [WARR1] The second is Shufflepuff, an implementation of a protocol called CoinShuffle[RUFF1] which allows several people to construct a Bitcoin transaction with an input and an output for each participant without any participant knowing who owns which output. CoinShuffle was invented by Tim Ruffing et al, and it is an upgrade of a protocol called CoinJoin, invented by Gregory Maxwell. This paper discusses the background, properties, applications, and design of bmd and Shufflepuff. There is also a report of a performance analysis on bmd.Item Bystander intervention in cyberbullying(2013-08) Brody, Nicholas Paul; Vangelisti, Anita L.Cyberbullying incidents often occur in the presence of other bystanders. The inaction of bystanders can augment the deleterious effects of bullying on a victim. However, bystanders can often take action to stop a cyberbullying incident or offer support to the victim. Two studies examined the association between several variables which were expected to influence the propensity for a bystander to take action in cyberbullying incidents -- the number of bystanders, the depersonalization/anonymity of the bystander, and the relational closeness between the bystander and the victim. Moreover, the first study addressed the need for more descriptive research into cyberbullying by examining the strategies and topics used by perpetrators. Results of both Study 1 and Study 2 provided support for the diffusion of responsibility effect. Specifically, a higher number of bystanders was negatively associated with a bystander's propensity to intervene and stop the incident. In Study 2, this effect was moderated by both depersonalization and closeness. That is, individuals were most likely to intervene when they did not feel depersonalized, the victim was a close friend, and there were a low number of bystanders. Moreover, in both Study 1 and Study 2 the perceived anonymity of bystanders negatively related to their propensity to intervene, and closeness with the victim was associated with a higher likelihood to intervene and support the victim. Finally, descriptive data illustrated the types and strategies of cyberbullying episodes which occur in a college-aged sample. Altogether, the results shed light on the interplay of context, relationships, and technology in the behavior of bystanders to a cyberbullying episode.Item Live for the moment : exploring the relationship between enactments of anonymity and time perspective(2020-05-07) Haggadone, Brad Alan; Ballard, Dawna I.; Scott, Craig R; McGlone, Matthew S; Barbour, Joshua BThis dissertation explores the relationship between identity and time. Specifically, it tests the relationship between time perspective and enactments of anonymity. Working from a sociomaterial lens, two studies were conducted using both an offline population and various online communities. The first study recruited students to fill out a questionnaire which included both questions about their online habits and a short form of the Zimbardo Time Perspective Inventory (Zhang et al., 2013). Additionally, participants were asked if they would be likely to use an anonymous, pseudonymous, or identified website in various hypothetical situations. The second study involved recruiting participants from various online communities (e.g., Facebook, Reddit, 4chan, and 8chan). Study 2 participants were also given a short version of The Zimbardo Time Perspective Inventory as well as questions about their participation in the online community they were recruited from. Findings of the studies suggest that there is a significant relationship between present-hedonism and anonymity if group identification is taken into account. There is also evidence of a positive relationship between a future time perspective and using identified websites. This evidence supports three main conclusions that can be drawn from the data. First, that the material structures of a community (i.e., the community’s level of identifiability) can influence their tendencies related to their time perspectives. Second, the mechanism the causes individuals to exhibit for hedonistic anti-social behavior may not be cruelty but because the individuals are not thinking through the consequences (for neither themselves nor others). Finally, it is possible for a more long-term temporal structure to be created by increasing the dimensions of identity present in CMC environments.Item Unobservable communication over untrusted infrastructure(2018-10-11) Angel, Sebastian Gomez; Witchel, Emmett; Peter, Simon; Walfish, Michael; Waters, Brent; Zeldovich, NickolaiIn the past decade there has been a significant increase in the collection of personal information and communication metadata (with whom users communicate, when, how often) by governments, Internet providers, companies, and universities. While there are many ongoing efforts to secure users’ communications, namely end-to-end encryption messaging apps and email services, safeguarding metadata remains elusive. This dissertation discusses the design, implementation, and evaluation of a system called Pung that makes progress on this front. Pung lets users exchange messages over the Internet without revealing any information in the process. Perhaps surprisingly, Pung achieves this strong privacy property even when all providers (ISPs, companies, servers, etc.) are arbitrarily malicious. As part of realizing Pung, this dissertation introduces two orthogonal but complementary techniques: SealPIR and probabilistic batch codes (PBCs). SealPIR is a new private information retrieval (PIR) library that reduces the communication costs of the most computationally efficient PIR protocol by over two orders of magnitude. SealPIR can also be used in other contexts to instantiate private services (for example, private variants of media streaming services). PBCs are a new data encoding that amortizes the computational costs associated with PIR, and are significantly more network-efficient than prior encodings. Thanks to these two techniques, our small deployment of Pung can scale out to support hundreds of thousands of users.