Non-sharing communities?:an empirical study of community detection for access control decisions

Social media users often find it difficult to make appropriate access control decisions which govern how they share their information with a potentially large audience on these platforms. Community detection algorithms have been previously put forth as a solution which can help users by automatically partitioning their friend network. These partitions can then be used by the user as a basis for making access control decisions. Previous works which leverage communities for enhancing access control mechanisms assume that members of the same community will have the same access to a user’s content, but whether or to what extent this assumption is correct is a lingering question. In this paper, we empirically evaluate a goodness of fit between the communities created by implementing 8 community detection algorithms on the friend networks of users and the access control decisions made by them during a user study. We also analyze whether personal characteristics of the users or the nature of the content play a role in the performance of the algorithms. The results indicate that community detection algorithms may be useful for creating default access control policies for users who exhibit a relatively more static access control behaviour. For users showing great variation in their access control decisions across the board (both in terms of number and actual members), we found that community detection algorithms performed poorly

Towards Sustainable Blockchains:Cryptocurrency Treasury and General Decision-making Systems with Provably Secure Delegable Blockchain-based Voting

The blockchain technology and cryptocurrencies, its most prevalent application, continue to gain acceptance and wide traction in research and practice within academia and the industry because of its promise in decentralised and distributed computing. Notably, the meteoric rise in the value and number of cryptocurrencies since the creation of Bitcoin in 2009 have ushered in newer innovations and interventions that addressed some of the prominent issues that affect these platforms. Despite the increased privacy, security, scalability, and energy-saving capabilities of new consensus protocols in newer systems, the development and management of blockchains, mostly, do not reflect the decentralisation principle despite blockchains being decentralised and distributed in their architecture. The concept of treasury has been identified as a tool to address this problem. We explore the idea of blockchain treasury systems within literature and practice, especially with relation to funding and decision-making power towards blockchain development and maintenance. Consequently, we propose a taxonomy for treasury models within cryptocurrencies. Thereafter, we propose an efficient community-controlled and decentralised collaborative decision-making mechanism to support the development and management of blockchains. Our proposed system incentivises participants and is proven secure under the universally composable (UC) framework while also addressing gaps identified from our investigation of prior systems e.g. non-private ballots and insecure voting. Furthermore, we adapt our system and propose a privacy-preserving general decision making system for blockchain governance that supports privacy-centric cryptocurrencies. Besides, using a set of metrics, we introduce a consensus analysis mechanism to enhance the utility of decision-making of the systems by evaluating individual choices against collective (system-wide) decisions. Finally, we provide pilot system implementations with benchmark results confirming the efficiency and practicality of our constructions