Cryptocurrencies and the underlying blockchain technology have greatly transformed our financial landscape and society as a whole. Blockchain, a secure-by-design technology, enables decentralized and distrustful parties to maintain a common transaction history through the process of consensus. The decentralization, transparency, and consensus-driven security properties promised by blockchain are unprecedented and can potentially enable novel applications which could only be accomplished by a trusted authority previously. To understand blockchain’s security implications and how a blockchain network could accommodate different application scenarios is essential to realizing its full potential. In this talk, I will introduce two of my research efforts which are at the intersection of blockchain and network security: (1) to understand the fundamental consensus security of blockchain and (2) to use and strengthen blockchain systems for solving previously unsolvable security and privacy problems. First, I will show my analytical work on evaluating the security of Nakamoto consensus, the famous protocol used by Bitcoin, from a novel networking perspective. Our proposed analytical model is able to quantify the impact of the P2P network’s heterogeneity in connectivity on several key consensus security metrics under different adversarial mining cases. Second, I will demonstrate how I use blockchain to address a long-standing privacy challenge facing our digitized society—data owners often lose control on how their data can be used once sharing the data with other parties, epitomized by the notorious Facebook-Cambridge Analytica data scandal. Our solution, named PrivacyGuard, combines blockchain smart contract with trusted computing hardware to empower individual data owners with complete control over the usage of their private data by data consumers. Lastly, I will conclude by highlighting my ongoing and future work towards trustworthy knowledge aggregation in blockchain and other emerging applications.

Yang Xiao is a Ph.D. candidate in Computer Engineering at Virginia Tech, advised by Professor Wenjing Lou. His research is focused on network and information security, with particular interests in security and privacy aspects of blockchain, distributed systems and networking, cyber-physical systems, and distributed machine learning. Yang has published his research in top venues for computer networking and security, including INFOCOM, ESORICS, ACSAC, AsiaCCS, and TDSC. His survey & tutorial work on blockchain consensus is well received in the research community with more than 300 citations since its publication in 2020 per Google Scholar. His long-term research goal is to solve the security and privacy challenges in distributed/decentralized systems of zero trust and develop trustworthy solutions for broader applications.